ABCMdb

ABCC7 p.Glu822*

ClinVar:	c.2464G>A , p.Glu822Lys ? , not provided c.2464G>T , p.Glu822* D , Pathogenic
CF databases:	c.2464G>T , p.Glu822* D , CF-causing c.2464G>A , p.Glu822Lys (CFTR1) ? , A nucleotide change, G->A was observed in exon 13 at position 2596 leading to E822K. The patient is 13 years old, and pancreatic insufficient. The other mutation is still unknown. This mutation was found once among 28 Belgian CF chromosomes.

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[hide] Qualitative and quantitative analysis of mRNA asso... Hum Genet. 2001 Dec;109(6):592-601. Epub 2001 Nov 6. Tzetis M, Efthymiadou A, Doudounakis S, Kanavakis E
Qualitative and quantitative analysis of mRNA associated with four putative splicing mutations (621+3A-->G, 2751+2T-->A, 296+1G-->C, 1717-9T-->C-D565G) and one nonsense mutation (E822X) in the CFTR gene.
Hum Genet. 2001 Dec;109(6):592-601. Epub 2001 Nov 6., [PMID:11810271]

Abstract [show]
The effects of four splicing mutations and one nonsense mutation on cystic fibrosis transmembrane conductance regulator ( CFTR) gene expression were investigated by reverse transcription-polymerase chain reaction analysis of mRNA extracted from nasal epithelial cells harvested from patients harbouring the mutations. We studied four subjects with 621+3A-->G, two with 2751+2T-->A, one with 296+1G-->C, two with 1717-9T-->C-D565G and seven with E822X and compared the results with CFTR mRNA from normal subjects. Our results showed that mutations 621+3A-->G, 2751+2T-->A, and 296+1G-->C, which disrupt the 5' splice donor sites of introns 4, 14a, and 2, respectively, and 1717-9T-->C-D565G, which possibly disrupts the exonic splicing enhancer sequences of exon 12 (owing to the missense mutation in cis), lead to the production of aberrantly spliced mRNA in nasal epithelial cells. Three of the splicing mutations (621+3A-->G, 2751+2T-->A, and 296+1G-->C) result in severe deficiency of normal CFTR mRNA and severe phenotype in the patients. This information is especially useful for mutation 621+3A-->G, which is found in other populations as well, and was initially reported as a polymorphism. The complex allele 1717-9T-->C-D565G results in aberrant splicing of CFTR mRNA with production of transcripts lacking exon 12 (major product), with minor amounts of transcripts revealing joint exon 11 and 12 skipping. Nonsense mutation E822X results in a severe reduction in mRNA levels to about 6% of wild type. Patients with the mutation have a severe clinical phenotype, with both the pancreatic and the pulmonary function affected.

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1 We studied four subjects with 621+3A→G, two with 2751+2T→A, one with 296+1G→C, two with 1717-9T→C-D565G and seven with E822X and compared the results with CFTR mRNA from normal subjects. Login to comment
6 Nonsense mutation E822X results in a severe reduction in mRNA levels to about 6% of wild type. Login to comment
19 Ultimately, however, all the disease-causing mutations result in defective cAMP-regulated Cl-secretion by epithelial cells, though for various reasons, namely defective pro- Maria Tzetis · Alexandra Efthymiadou · Stavros Doudounakis · Emmanuel Kanavakis Qualitative and quantitative analysis of mRNA associated with four putative splicing mutations (621+3A→G, 2751+2T→A, 296+1G→C, 1717-9T→C-D565G) and one nonsense mutation (E822X) in the CFTR gene Hum Genet (2001) 109:592-601 DOI 10.1007/s00439-001-0631-0 Received: 18 June 2001 / Accepted: 13 September 2001 / Published online: 6 November 2001 ORIGINAL INVESTIGATION M. Tzetis · A. Efthymiadou · E. Kanavakis (✉) Department of Medical Genetics, Athens University, "Aghia Sophia" Children`s Hospital, Thivon & Livadias, Athens, 11527, Greece e-mail: ekanavak@cc.uoa.gr, Tel.: +30-1-7467460, Fax: +30-1-7795553 S. Doudounakis Cystic Fibrosis Unit, "Aghia Sophia" Children`s Hospital, Athens, Greece (c) Springer-Verlag 2001 tein production (class I), defective protein processing (class II), defective regulation (class III), defective conduction (class IV), or defective synthesis (class V) (Welsh and Smith 1993; Zielenski and Tsui 1995). Login to comment
31 Additionally we studied one nonsense mutation, E822X. Login to comment
36 Patients and controls Nasal epithelial cells were collected from four subjects with 621+3A→G (all compound heterozygotes), two with 2751+2T→A (one compound heterozygote and one carrier), one with 296+1G→C, two with 1717-9T→C-D565G (both only carriers), and seven with E822X (three compound heterozygotes, two homozygotes, and two carriers). Login to comment
54 Samples for the E822X mutation were reverse-transcribed into cDNA with an initial set of primers spanning exons 13 to 14a (Table 2), one of which contains a 3` mismatch which, in combination with the normal sequence at E822 (G@2596; E822X: G→T@2596), creates a restriction site for Hph1. Login to comment
58 The resulting PCR products derived from cDNA templates for each of the above mutations, including the digested product for the E822X mutation, were electrophoresed on a 6% acrylamide denaturing gel using an automatic DNA sequencer (Vistra, model 725-Molecular Dynamics). Login to comment
60 ?--Recurrent episodes ofpneu- monia E822X/D110E21M11mos127No<50%50%-75%PS100%110%-Pa,Sa E822X/F508del8M5yrs113No<75%90%-97%PI141%133%Nasal polyposis Sa,Klebsiella pneumoniae Gallblad- derstones, rectal proptosis E822X/N1303K11F1mo102.5/116.1/ 104.2 No<25%<50%PI24%27%-Pa,SaDIOS, hepatic disease E822X/E822X4MBirth83/82.9Yes50%25%-50%PI---Sa,Hi,Pa E822X/E822X15F1mo129.4/136.5/ 130.5 No>10%>10%PI50%54%Pa, xanthomonas maltiphilia,Sa PI,Pancreaticinsufficiency;PS,pancreaticsufficiency;Sa,Staphylococcus;Hi,Haemophilus;Pa,Pseudomonasaureus;Ps,Pseudomonas;DIOS,distalintestinalobstruction syndrome aHeterozygotesforthemutationsstudiedarenotincludedinthetable bNotaCFpatient,heterozygotewithrecurrentepisodesofpneumonia Each analysis for each sample was repeated three times to ensure accurate quantitation and all measurements were combined to reach the final result for each of the fragments analyzed. Login to comment
98 E822X One-step extension of the fluorescent primer E822Xrev (cDNA products of seven subjects for mutation E822X as well as two controls), followed by Hph1 digestion of the product, allowed differentiation between cDNA derived from the normal (79 bp plus 31 bp) and mutant (110 bp) alleles (Fig.4). Login to comment
99 Quantitation of cDNA produced from the E822X allele indicated that the mutation is associated with severely reduced mRNA levels (6.3%±1.9%) compared with normal, and this should result in the production of minimal amounts of truncated protein. Login to comment
100 Discussion Analysis of CFTR mRNA from nasal epithelial cells, which are the cells biologically relevant to the disease process in CF, shows that mutations 621+3A→G, 2751+2T→A, 296+1G→C, and double allele 1717-9T→C-D565G result in the production of aberrantly spliced mRNA transcripts and that nonsense mutation E822X results in severe reduction of CFTR mRNA. Login to comment
135 Splicing 599 Fig.4A,B mRNA results for mutation E822X. Login to comment
137 A mRNA RT-PCR products analysed by 2% agarose gel electrophoresis. M, Marker lane, phiX174/ HaeIII DNA; lanes 1, 2 and 6: samples homozygous for mutation E822X; lanes 3, 4, 7, 8 and 9: samples heterozygous for E822X; lane 5: normal control; 110 bp: mutant transcript; 79 bp: normal transcript. Login to comment
138 B Schematic representation of method of analysis used (showing location of primers) for the RT-PCR for the study of mutation E822X. Login to comment
140 Underlined and bold nucleotides represent primer mismatch (G→A) and E822X mutation (G→T) enhancers are usually located within 100 nucleotides of the 3` splice site and their potential target is thought to be U2AF, which binds to the 3` splice site (Graveley et al. 1998). Login to comment
142 Transcripts produced from the E822X allele indicated that the mutation is associated with severely reduced mRNA levels (6.3%), resulting in the production of minimal amounts of truncated protein. Login to comment
145 Nonsense mutation E822X is common in the Greek population, accounting for 1.7% of CF chromosomes. Login to comment
146 The patients with E822X were diagnosed between birth and 5 years with high sweat test values and were all pancreatic insufficient except for the patient carrying a mild mutation (D110 E) in trans (Table 1). Login to comment
149 The nonsense mutation (E822X) results in undetectable CFTR mRNA in nasal epithelial cells, possibly owing to the nonsense-mediated mRNA decay pathway; therefore minimal amounts of truncated protein are expected to be produced from the mutant allele. Login to comment

[hide] Cystic fibrosis: a worldwide analysis of CFTR muta... Hum Mutat. 2002 Jun;19(6):575-606. Bobadilla JL, Macek M Jr, Fine JP, Farrell PM
Cystic fibrosis: a worldwide analysis of CFTR mutations--correlation with incidence data and application to screening.
Hum Mutat. 2002 Jun;19(6):575-606., [PMID:12007216]

Abstract [show]
Although there have been numerous reports from around the world of mutations in the gene of chromosome 7 known as CFTR (cystic fibrosis transmembrane conductance regulator), little attention has been given to integrating these mutant alleles into a global understanding of the population molecular genetics associated with cystic fibrosis (CF). We determined the distribution of CFTR mutations in as many regions throughout the world as possible in an effort designed to: 1) increase our understanding of ancestry-genotype relationships, 2) compare mutational arrays with disease incidence, and 3) gain insight for decisions regarding screening program enhancement through CFTR multi-mutational analyses. Information on all mutations that have been published since the identification and cloning of the CFTR gene's most common allele, DeltaF508 (or F508del), was reviewed and integrated into a centralized database. The data were then sorted and regional CFTR arrays were determined using mutations that appeared in a given region with a frequency of 0.5% or greater. Final analyses were based on 72,431 CF chromosomes, using data compiled from over 100 original papers, and over 80 regions from around the world, including all nations where CF has been studied using analytical molecular genetics. Initial results confirmed wide mutational heterogeneity throughout the world; however, characterization of the most common mutations across most populations was possible. We also examined CF incidence, DeltaF508 frequency, and regional mutational heterogeneity in a subset of populations. Data for these analyses were filtered for reliability and methodological strength before being incorporated into the final analysis. Statistical assessment of these variables revealed that there is a significant positive correlation between DeltaF508 frequency and the CF incidence levels of regional populations. Regional analyses were also performed to search for trends in the distribution of CFTR mutations across migrant and related populations; this led to clarification of ancestry-genotype patterns that can be used to design CFTR multi-mutation panels for CF screening programs. From comprehensive assessment of these data, we offer recommendations that multiple CFTR alleles should eventually be included to increase the sensitivity of newborn screening programs employing two-tier testing with trypsinogen and DNA analysis.

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110 Germany ∆F508 (71.8%) 1789+5G→A (0.9%) 87.6 76.7 17 5662/1316 Dörk et al. [1992]; Dörk et al. R553X (2.0%) 3272-26A→G (0.9%) [1994]; Tümmler et al. [1996]; N1303K (1.8%) W1282X (0.7%) Estivill et al. [1997]; Dörk et G542X (1.2%) 2143delT (0.7%) al. [2000] R347P (1.2%) 1078delT (0.6%) CFTRdele2,3 (1.2%) 2183AA→G (0.6%) 3849+10KbC→T (1.0%) 2184insA (0.6%) G551D (0.9% 3659delC (0.6%) 1717-1G→A (0.9%) Greece ∆F508 (52.9%) 3272-26A→G (0.8%) 82.2 67.6 22 2097/718 Kanavakis et al. [1995]; Estivill 621+1G→T (5.0%) R1070Q (0.8%) et al. [1997]; Tzetis et al. G542X (4.1%) W496X (0.7%) [1997]; Macek et al. [2002] N1303K (3.3%) 621+3A→G (0.7%) 2183AA→G (1.8%) ∆I507 (0.7%) 2789+5G→A (1.7%) W1282X (0.7%) E822X (1.6%) 574delA (0.7%) R117H (1.2%) 1677delTA (0.7%) R334W (1.1%) A46D (0.6%) R1158X (1.0%) 3120+1G→A (0.6%) G85E (1.0%) G551D (0.5%) Hungary ∆F508 (54.9%) W1282X (1.8%) 68.3 46.6 9 1133/976 CFGAC [1994]; Estivill et al. 1717-1G→A (1.9%) G542X (1.7%) [1997]; Macek et al. [2002] R553X (2.1%) N1303K (1.3%) Y1092X (1.8%) G551D (1.0%) S1196X (1.8%) Ireland ∆F508 (70.4%) G542X (1.0%) 82.1 67.4 7 801/509 CFGAC [1994]; Estivill et al. G551D (5.7%) 621+1G→T (0.8%) [1994] R117H (2.4%) 1717-1G→A (0.6%) R560T (1.2%) Italy ∆F508 (50.9%) ∆I507 (0.65%) 60.3 36.4 9 3524 Estivill et al. [1997] (total) G542X (3.1%) W1282X (0.62%) 1717-1G→A (1.6%) Y122K (0.59%) N1303K (1.4%) G551D (0.53%) R553X (0.94%) Italy ∆F508 (47.6%) R553X (1.3%) 87.1 75.9 15 225 Bonizzato et al. [1995] (Northeast) R1162X (9.8%) 2789+G→A (1.3%) 2183AA→G (9.3%) Q552X (1.3%) N1303K (4.0%) 621+1G→T (0.9%) G542X (2.7%) W1282X (0.9%) 711+5G→A (2.7%) 3132delTG (0.9%) 1717-1G→A (2.2%) 2790-2A→G (0.9%) G85E (1.3%) TABLE 1. Continued. Estimated Projected detection of Number of Number of Country/ allele two CFTR mutations chromosomes Region Mutation array detectiona mutationsb includedc (max/min)d Reference WORLDWIDEANALYSISOFCFTRMUTATIONS583 Italy ∆F508 (56.4%) 711+1G→T (1.3%) 85.7 73.4 13 660/396 Castaldo et al. [1996]; Castaldo (southern) N1303K (6.8%) G1244E (1.3%) et al. [1999] G542X (5.7%) R1185X (1.3%) W1282X (3.8%) L1065P (1.3%) 1717-1G→A (2.3%) R553X (1.1%) 2183AA→G (1.9%) I148T (0.7%) 4016insT (1.8%) Latvia 1) DF508 (58.3%) 4) CFTRdele2,3 (2.8%) - - 6 36 Dörk et al. [2000]; Macek et al. 2) 3849+10KbC®T (8.3%) 5) W1282X (2.8%) [2002] 3) N1303K (5.6%) 6) 394delTT (2.8%) Lithuania ∆F508 (31.0%) N1303K (2.0%) 39.0 15.2 4 94 Dörk et al. [2000]; Macek et al. R553X (4.0%) CFTRdele2,3 (2.0%) [2002] Macedonia ∆F508 (54.3%) 711+3A→G (1.0%) 69.2 47.9 12 559/226 Petreska et al. [1998]; Dörk et G542X (4.2%) 3849G→A (1.0%) al. [2000]; Macek et al. N1303K (2.0%) 2184insA (0.9%) [2002] CFTRdele2,3 (1.3%) 457TAT→G (0.7%) 621+1G→T (1.3%) V139E (0.7%) 611-1G→T (1.2%) 1811+1G→C (0.6%) Netherlands ∆F508 (74.2%) R1162X (0.9%) 86.8 75.3 9 3167/1442 Gan et al. [1995]; Estiville et al. A455E (4.7%) S1251N (0.9%) [1997]; Collee et al. [1998] G542X (1.8%) N1303K (0.9%) 1717-1G→A (1.5%) W1282X (0.7%) R553X (1.2%) Norway ∆F508 (60.2%) G551D (1.2%) 69.8 48.7 6 410/242 Schwartz et al. [1994]; Estivill 394delTT (4.2%) G542X (0.6%) et al. [1997] R117H (3.0%) N1303K (0.6%) Poland ∆F508 (57.1%) CFTRdele2,3 (1.8%) 73.5 54.0 11 4046/1726 CFGAC [1994]; Estivill et al. 3849+10Kb C→T (2.7%) R560T (1.5%) [1997]; Dörk et al [2000]; G542X (2.6%) W1282X (0.7%) Macek et al. [2002] 1717-1G→A (2.4%) ∆I507 (0.5%) R553X (1.9%) G551D (0.5%) N1303K (1.8%) Portugal ∆F508 (44.7%) R334W (0.7%) 49.7 24.7 5 739/454 CFGAC [1994]; Estivill et al. G542X (1.6%) N1303K (0.7%) [1997] R1066C (2.0%) Romania ∆F508 (36.6%) G542X (1.4%) 51.5 26.5 11 224/74 CFGAC [1994]; Estivill et al. 2043delG (2.0%) R553X (1.4%) [1997]; Popa et al. [1997]; W1282X (1.7%) G576X (1.4%) Macek et al. [2002] 1717-2A→G (1.4%) 1898+1G→A (1.4%) I148T (1.4%) 2183AA→G (1.4%) 621+1G→T (1.4%) Russia ∆F508 (54.4%) 552insA (0.9%) 70.7 50.0 12 5073/2562 CFGAC [1994]; Estivill et al. CFTRdele2,3 (5.0%) G542X (0.9%) [1997]; Dörk et al. [2000]; R553X (3.5%) R334W (0.9%) Macek et al. [2002] 2183AA→G (1.3%) 1677delTA (0.8%) W1282X (1.0%) Y122X (0.5%) 394delTT (1.0%) 1367del5 (0.5%) (Continued) BOBADILLAETAL. Login to comment
112 Jewish 1) 405+1G®A (48.0%) 3) W1282X (17.0%) - - 4 23 Kerem et al. [1995] (Tunisia) 2) DF508 (31.0%) 4) 3849+10KbC®T (4.0%) Jewish 1) G85E 4) G542X - - 6 10 Kerem et al. [1995] (Turkey) 2) DF508 5) 3849+10KbC®T 3) W1282X 6) W1089X Jewish (Yemen) None - - 0 5 Kerem et al. [1995] Lebanon 1) DF508 (35.0%) 6) 4096-28G®A (2.5%) - - 9 40 Desgeorges et al. [1997] 2) W1282X (20.0%) 7) 2789+5G®A (2.5%) 3) 4010del4 (10.0%) 8) M952I (2.5%) 4) N1303K (10.0%) 9) E672del (2.5%) 5) S4X (5.0%) Reunion ∆F508 (52.0%) 1717-1G→A (0.7%) 90.4 81.7 9 138 Cartault et al. [1996] Island Y122X (24.0%) G542X (0.7%) 3120+1G→A (8.0%) A309G (0.7%) A455E (2.2%) 2789+5G→A (0.7%) G551D (1.4%) Saudi North: 3) H139L - - North 1 49 families El-Harith et al. [1997]; Arabia 1) 1548delG 4) L1177X Central 3 Kambouris et al. [1997]; Central: 5) DF508 South 4 Banjar et al. [1999] 1)I1234V 6) 3120+1G®A West 9 2)1548delG 7) 425del42 East 6 3)DF508 8) R553X South: 9) N1303K 1) I1234V East: 2) 1548delG 1) 3120+1G®A 3) 711+1G®T 2) H139L 4) 3120+1G®A 3) 1548delG West: 4) DF508 1) I1234V 5) S549R 2) G115X 6) N1303K Tunisia ∆F508 (17.6%) G85E (2.6%) 58.7 34.5 11 78 Messaoud et al. [1996] G542X (8.9%) W1282X (2.6%) 711+1G→T (7.7%) Y122X (1.3%) N1303K (6.4%) T665S (1.3%) 2766del8NT (6.4%) R47W+D1270N (1.3%) R1066C (2.6%) Turkeye ∆F508 (24.5%) 1066L (1.3%) 80.6 65.0 36 1067/670 Yilmaz et al. [1995]; Estivill et al. 1677delTA (4.1%) E822X (1.3%) [1997]; Onay et al. [1998]; 2789+5G→A (3.9%) 2183+5G→A+2184insA (1.3%) Macek et al. [2002] 2181delA (3.8%) D110H (0.8%) R347H (3.6%) P1013L (0.8%) N1303K (2.9%) 3172delAC (0.8%) 621+1G→T (2.6%) 1259insA (0.8%) G542X (2.6%) M1028I (0.8%) TABLE 1. Continued. Estimated Projected detection of Number of Number of Country/ allele two CFTR mutations chromosomes Region Mutation array detectiona mutationsb includedc (max/min)d Reference WORLDWIDEANALYSISOFCFTRMUTATIONS587 E92K (2.6%) 4005+1G→A (0.7%) A96E (2.6%) W1282X (0.7%) M152V (2.6%) I148T (0.6%) 2183AA→G (2.5%) R1162X (0.6%) 296+9A→T (1.6%) D1152H (0.6%) 2043delG (1.4%) W1098X (0.6%) E92X (1.4%) E831X (0.6%) K68N (1.4%) W496X (0.6%) G85E (1.3%) F1052V (0.5%) R1158X (1.3%) L571S (0.5%) United Arab S549R (61.5%) ∆F508 (26.9%) 88.4 78.1 2 86/52 Frossard et al. [1988]; Emirates Frossard et al. [1999] North/Central/South Americas Argentina ∆F508 (58.6%) N1303K (1.8%) 69.1 47.7 5 326/228 CFGAC [1994]; Chertkoff et al. W1282X (3.9%) 1717-1G→A (0.9%) [1997] G542X (3.9%) Brazilf ∆F508 (47.7%) W1282X (1.3%) 66.8 44.6 10 820/500 CFGAC [1994]; Cabello et al. (total) G542X (7.2%) G85E (1.3%) [1999]; Raskin et al. [1999]; R1162X (2.5%) R553X (0.7%) Bernardino et al. [2000] R334W (2.5%) L206W (0.6%) N1303K (2.4%) 2347delG (0.6%) South East: >∆F508, G542X South: >N1303K Brazil ∆F508 (31.7%) N1303K (2.5%) 42.5 18.1 3 120 Parizotto and Bertuzzo [1997] (Sao Paulo) G542X (8.3%) Canada ∆F508 (59.0%) G542X (0.5%) 98.5 97.0 13 381/200 Rozen et al. [1992]; (Lac St. Jean) 621+1G→T (24.3%) N1303K (0.5%) De Braekeleer et al. [1998] A445E (8.2%) Q890X (0.5%) Y1092X (1.2%) S489X (0.5) 711+1G→T (1.0%) R117C (0.5%) I148T (1.0%) R1158 (0.5%) G85E (0.8%) Canada ∆F508 (71.4%) ∆I507 (1.3%) 90.9 82.6 7 77 Rozen et al. [1992] (Quebec City) 711+1G→T (9.1%) Y1092X (1.3%) 621+1G→T (5.2%) N1303K (1.3%) A455E (1.3%) Canada ∆F508 (70.9%) W1282X (0.9%) 82.0 67.2 10 632 Kristidis et al. [1992] (Toronto) G551D (3.1%) R117H (0.9%) G542X (2.2%) 1717-1G→A (0.6%) 621+1G→T (1.3%) R560T (0.6%) N1303K (0.9%) ∆I507 (0.6%) Chile ∆F508 (29.2%) R553X (4.2%) 33.4 11.2 2 72 Rios et al. [1994] Columbia 1) DF508 (35.4%) 3) N1303K (2.1%) - - 4 48 Restrepo et al. [2000] 2) G542X (6.3%) 4) W1282X (2.1%) Ecuador 1) DF508 (25%) - - 1 20 Paz-y-Mino et al. [1999] (Continued) BOBADILLAETAL. Login to comment

[hide] Multiplex sequence variation detection throughout ... Mol Hum Reprod. 2002 Sep;8(9):880-6. Vrettou C, Tzetis M, Traeger-Synodinos J, Palmer G, Kanavakis E
Multiplex sequence variation detection throughout the CFTR gene appropriate for preimplantation genetic diagnosis in populations with heterogeneity of cystic fibrosis mutations.
Mol Hum Reprod. 2002 Sep;8(9):880-6., [PMID:12200467]

Abstract [show]
Cystic fibrosis (CF) is one of the most important genetic diseases requiring prevention programmes. Preimplantation genetic diagnosis (PGD) represents an alternative to prenatal diagnosis, and is especially appropriate for couples with an unsuccessful reproductive history. For clinical application, protocols must be optimized to minimize PCR failure, allelic drop-out (ADO) and contamination, while simultaneously detecting a wide spectrum of CF genotypes. We have developed a flexible multiplex PCR protocol allowing analysis of sequence variations in any combination amongst seven CFTR gene exons (4, 10, 11, 13 in two parts, 14b, 17b and 21) by nested PCR and denaturing gradient gel electrophoresis analysis, along with analysis of a fluorescently labelled intragenic microsatellite (IVS8CA). The experiments were carried out on 390 single lymphocytes from three CF patients, one heterozygote and one non-CF individual. PCR efficiency of the exons ranged from 90 to 100%, and ADO from 0 to 3.8%. IVS8CA was co-amplified with a PCR efficiency of 92.4 and 10.8% ADO. The present method overcomes the need for separate assays for each CFTR gene mutation. Additionally, it facilitates analysis of any informative linked polymorphic sequence variation (within the seven exons) along with analysis of a microsatellite, which is useful (when informative) for minimizing misdiagnosis and/or indirect diagnosis. This method proved robust and flexible for diagnosing diverse CF genotype combinations in single cells.

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24 cells PCR ADO/total polymorphism (length bp) amplified product (%) cells (%) Patient 1 F508del 25 (196) 10 50 47 (94.0) 0/47 (0) 621 ϩ 1G→T 23 (192) 4 48 (96.0) 1/48 (2.1) Patient 2 N1303K 25 (196) 21 85 80 (94.1) 3/80 (3.8) 2789 ϩ 5G→A 18 (182) 14b 85 (100) 2/85 (2.4) Patient 3 E822X 17 (180) 13 part b 80 72 (90.0) 1/72 (1.4) F1052V 18 (182) 17b 75 (93.8) 2/75 (2.6) Heterozygotea 1719-9T→C 17 (180) 11 75 75 (100.0) 0/75 (0) R668C 13 part a Normal allele 18 (182) 74 (98.7) 1/74 (1.4) Microsatellite 290 268 (92.4) 29/268 (10.8) IVS8CA aIndividual heterozygote for D565G mutation in exon 12 (not included in assay) had two polymorphisms in cis to D565G (1719-9T→C in exon 11 and R668C in exon 13 part a), which were also in cis with 17 CA repeats in IVS8. Login to comment

[hide] Longitudinal follow-up of exocrine pancreatic func... J Pediatr Gastroenterol Nutr. 2003 Apr;36(4):474-8. Walkowiak J, Nousia-Arvanitakis S, Agguridaki C, Fotoulaki M, Strzykala K, Balassopoulou A, Witt M, Herzig KH
Longitudinal follow-up of exocrine pancreatic function in pancreatic sufficient cystic fibrosis patients using the fecal elastase-1 test.
J Pediatr Gastroenterol Nutr. 2003 Apr;36(4):474-8., [PMID:12658038]

Abstract [show]
BACKGROUND: A progressive decline in pancreatic function is possible in cystic fibrosis (CF) patients with exocrine pancreatic sufficiency. The secretin-cholecystokinin test is invasive and not acceptable as a repeatable procedure for children. Steatorrhea, conversely, has low sensitivity. Therefore, the aim of the present study was to evaluate the usefulness of the noninvasive fecal elastase-1 (E1) test for the longitudinal assessment of exocrine pancreatic function (EPF) in pancreatic-sufficient (PS) CF patients. METHODS: One hundred eighty-four CF patients were included in the study. In all subjects, E1 concentrations and fecal fat excretion were measured. PS patients were followed for 5 years. RESULTS: At the beginning of the study, 35 (19.0%) CF patients were PS, and 32 (17.4%) had normal E1 concentrations. Longitudinal measurements of E1 concentrations in PS patients with CF demonstrated stable enzyme output in 27 and gradual decrease in 8. The decrease was rapid in five infant patients and gradual in three older patients. The decrease of E1 concentrations preceded the appearance of steatorrhea in all eight subjects. CONCLUSIONS: The decline of EPF in patients with CF appears more frequently during the first months and years of life. However, late PS to pancreatic-insufficient (PI) conversion is also possible. The appearance of maldigestion is preceded by the decrease of fecal E1 concentration. Thus, the fecal E1 test is a helpful screening tool for the longitudinal assessment of declining EPF in PS patients with CF to demonstrate pancreatic deterioration. In suspected patients, fecal fat excretion should be assessed.

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51 RESULTS Among the patients studied, the following mutations of the CFTR gene were present (n): ⌬F508 (223), 621+G-T (10), N1303K (9), 3849+10kbC-T (6), G542X (5), CFTRdele2,3(21kB) (4), E822X (4), 1717-1G-A (3), E836X (3), G1069-L88X (2), R533X (1), G85E (1), 1677delTA (1), G1069R (1), 1525-1G-A (1), and 2789+5G-A (1). Login to comment
64 Among PS patients with stable enzyme output, the following genotypes were found: 3849+10kbC-T/3849+10kbC-T (n ‫ס‬ 2), ⌬F508/3849+10kbC-T (n ‫ס‬ 2), ⌬F508/1525-1G-A (n ‫ס‬ 1), ⌬F508/M (n ‫ס‬ 5), E822X/M (n ‫ס‬ 1), 2789+5G-A (n ‫ס‬ 1), and M/M (n ‫ס‬ 12). Login to comment

[hide] Genotype/phenotype correlation of the G85E mutatio... Eur Respir J. 2004 May;23(5):679-84. Decaestecker K, Decaestecker E, Castellani C, Jaspers M, Cuppens H, De Boeck K
Genotype/phenotype correlation of the G85E mutation in a large cohort of cystic fibrosis patients.
Eur Respir J. 2004 May;23(5):679-84., [PMID:15176679]

Abstract [show]
In this European study, the phenotype in 68 patients, homozygous or compound heterozygous for the G85E mutation, was investigated. Each index case was compared with two cystic fibrosis (CF) patients from the same clinic, matched for age and sex: one with pancreatic sufficiency (PS) and one with pancreatic insufficiency (PI). When comparing 31 G85E/F508del and F508del/F508del patients, there were no differences in median age at diagnosis, mean sweat chloride value, most recent weight for height, most recent forced expiratory volume in one second % predicted, prevalence of chronic Pseudomonas aeruginosa colonisation and typical CF complications. However, PI was less frequent in the G85E/F508del group. Comparison of 55 G85E patients (with second mutation known and not classified as mild) with PS controls (n=44) showed that the G85E patients had a significantly higher sweat chloride, more often failure to thrive at diagnosis, higher prevalence of PI, worse current weight for height, higher prevalence of chronic P. aeruginosa colonisation and liver cirrhosis. Pulse-chase experiments revealed that G85E cystic fibrosis transmembrane conductance regulator failed to mature on a M470 as well as on a V470 background. Therefore, G85E is a class II mutation. Although there is variability in its clinical presentation, G85E mutation results in a severe phenotype.

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93 1 G85E/W496X 1 F508del# /N1303K# 1 G85E/N1303K# 1 T388I/R1158X 1 G85E/711z5GRA} 1 3272-26AwG} /E822X 1 G85E/R334W} 1 F508del# /R334W} 1 Total 68 574delA/2789z5GRA 1 F508del# /3272-26ARG} 1 F508del# /R352Q 1 F508del# /3272-26AwG} 1 R334W} /444delA 1 L206W/3272-26ARG} 1 F508del# /F508del# 1 L206W/? Login to comment

[hide] Pharmacological induction of CFTR function in pati... Pediatr Pulmonol. 2005 Sep;40(3):183-96. Kerem E
Pharmacological induction of CFTR function in patients with cystic fibrosis: mutation-specific therapy.
Pediatr Pulmonol. 2005 Sep;40(3):183-96., [PMID:15880796]

Abstract [show]
CFTR mutations cause defects of CFTR protein production and function by different molecular mechanisms. Mutations can be classified according to the mechanisms by which they disrupt CFTR function. This understanding of the different molecular mechanisms of CFTR dysfunction provides the scientific basis for the development of targeted drugs for mutation-specific therapy of cystic fibrosis (CF). Class I mutations are nonsense mutations that result in the presence of a premature stop codon that leads to the production of unstable mRNA, or the release from the ribosome of a short, truncated protein that is not functional. Aminoglycoside antibiotics can suppress premature termination codons by disrupting translational fidelity and allowing the incorporation of an amino acid, thus permitting translation to continue to the normal termination of the transcript. Class II mutations cause impairment of CFTR processing and folding in the Golgi. As a result, the mutant CFTR is retained in the endoplasmic reticulum (ER) and eventually targeted for degradation by the quality control mechanisms. Chemical and molecular chaperones such as sodium-4-phenylbutyrate can stabilize protein structure, and allow it to escape from degradation in the ER and be transported to the cell membrane. Class III mutations disrupt the function of the regulatory domain. CFTR is resistant to phosphorylation or adenosine tri-phosphate (ATP) binding. CFTR activators such as alkylxanthines (CPX) and the flavonoid genistein can overcome affected ATP binding through direct binding to a nucleotide binding fold. In patients carrying class IV mutations, phosphorylation of CFTR results in reduced chloride transport. Increases in the overall cell surface content of these mutants might overcome the relative reduction in conductance. Alternatively, restoring native chloride pore characteristics pharmacologically might be effective. Activators of CFTR at the plasma membrane may function by promoting CFTR phosphorylation, by blocking CFTR dephosphorylation, by interacting directly with CFTR, and/or by modulation of CFTR protein-protein interactions. Class V mutations affect the splicing machinery and generate both aberrantly and correctly spliced transcripts, the levels of which vary among different patients and among different organs of the same patient. Splicing factors that promote exon inclusion or factors that promote exon skipping can promote increases of correctly spliced transcripts, depending on the molecular defect. Inconsistent results were reported regarding the required level of corrected or mutated CFTR that had to be reached in order to achieve normal function.

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53 This class may include promoter mutations that reduce transcription TABLE 1- Classes of CFTR Mutations1 Class Mutations I Stop codons: W1282X, G542X, R1162X, R553X, E822X Splicing mutations that completely abolish protein synthesis: 1717 À 1G ! Login to comment

[hide] Contribution of the CFTR gene, the pancreatic secr... Clin Genet. 2007 May;71(5):451-7. Tzetis M, Kaliakatsos M, Fotoulaki M, Papatheodorou A, Doudounakis S, Tsezou A, Makrythanasis P, Kanavakis E, Nousia-Arvanitakis S
Contribution of the CFTR gene, the pancreatic secretory trypsin inhibitor gene (SPINK1) and the cationic trypsinogen gene (PRSS1) to the etiology of recurrent pancreatitis.
Clin Genet. 2007 May;71(5):451-7., [PMID:17489851]

Abstract [show]
Acute recurrent/chronic pancreatitis (CP) is a complex multigenic disease. This is a case-control study consisting of 25 Greek patients with CP and a control population of 236 healthy Greek subjects. The whole coding area and neighboring intronic regions of the three genes were screened. Seventeen of 25 patients (68%) had mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene: nine compound heterozygotes with either mild or severe mutations and eight heterozygotes. Four patients (16%) carried CFTR-modulating haplotypes V470-TG11-T5 and V470-TG12-T7. All were negative for PRSS1 gene mutations, while variants c.486C/T and c.738C/T were found in nine patients each, three homozygotes for the minor alleles. Two carried SPINK1 gene mutation p.N34S, one being transheterozygote with CFTR mutation p.F1052V. The promoter variant -253T>C was found in four individuals (one homozygous for the minor allele), all four being transheterozygotes with mutations in the CFTR gene as well. Finally two carried c.272C/T in the 3' untranslated region, one being a p.N34S carrier as well. In total, 80% (20/25) of patients had a molecular defect in one or both of the CFTR and SPINK1 genes, suggesting that mutations/variants in the CFTR plus or minus mutations in the SPINK1, but not the PRSS1 gene, may confer a high risk for recurrent pancreatitis.

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63 Nine patients (36%) were compound heterozygotes for two CFTR mutations, both mild (class IV or V): p.I148T/p.R75Q, c.278915G.A/p.R75Q or mild and severe: three with p.F508del/p.R334W and four withc.444delA/p.R334W,p.E822X/c.278915G.A, p.E822X/p.R347H and p.F508del/c.3272226A.G, each. Login to comment

[hide] Localization studies of rare missense mutations in... Hum Mutat. 2008 Nov;29(11):1364-72. Krasnov KV, Tzetis M, Cheng J, Guggino WB, Cutting GR
Localization studies of rare missense mutations in cystic fibrosis transmembrane conductance regulator (CFTR) facilitate interpretation of genotype-phenotype relationships.
Hum Mutat. 2008 Nov;29(11):1364-72., [PMID:18951463]

Abstract [show]
We have been investigating the functional consequences of rare disease-associated amino acid substitutions in the cystic fibrosis transmembrane conductance regulator (CFTR). Mutations of the arginine residue at codon 1070 have been associated with different disease consequences; R1070P and R1070Q with "severe" pancreatic insufficient cystic fibrosis (CF) and R1070W with "mild" pancreatic sufficient CF or congenital bilateral absence of the vas deferens. Intriguingly, CFTR bearing each of these mutations is functional when expressed in nonpolarized cells. To determine whether R1070 mutations cause disease by affecting CFTR localization, we created polarized Madin Darby canine kidney (MDCK) cell lines that express either wild-type or mutant CFTR from the same genomic integration site. Confocal microscopy and biotinylation studies revealed that R1070P was not inserted into the apical membrane, R1070W was inserted at levels reduced from wild-type while R1070Q was present in the apical membrane at levels comparable to wild-type. The abnormal localization of CFTR bearing R1070P and R1070W was consistent with deleterious consequences in patients; however, the profile of CFTR R1070Q was inconsistent with a "severe" phenotype. Reanalysis of 16 patients with the R1070Q mutation revealed that 11 carried an in cis nonsense mutation, S466X. All 11 patients carrying the complex allele R1070Q-S466X had severe disease, while 4 out of 5 patients with R1070Q had "mild" disease, thereby reconciling the apparent discrepancy between the localization studies of R1070Q and the phenotype of patients bearing this mutation. Our results emphasize that localization studies in relevant model systems can greatly assist the interpretation of the disease-causing potential of rare missense mutations.

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172 Of the two patients diagnosed with CF, a female patient with the E822X (c.2464G4T; p.Glu822X) mutation in her other CFTR gene had pancreatic insufficient CF and a patient carrying 278915G4A (c.265715G4A) had pancreatic-sufficient CF. Login to comment
173 The E822X mutation has been associated with pancreatic-insufficient CF while 278915G4T is a pancreatic-sufficient mutation (www.genet.sickkids.on.ca/cftr). Login to comment

[hide] Is CFTR 621+3 A>G a cystic fibrosis causing mutati... J Hum Genet. 2010 Jan;55(1):23-6. Epub 2009 Nov 6. Forzan M, Salviati L, Pertegato V, Casarin A, Bruson A, Trevisson E, Di Gianantonio E, Clementi M
Is CFTR 621+3 A>G a cystic fibrosis causing mutation?
J Hum Genet. 2010 Jan;55(1):23-6. Epub 2009 Nov 6., [PMID:19893581]

Abstract [show]
The 621+3 A>G variant of the CFTR gene was initially detected in four Greek patients with a severe form of cystic fibrosis, and it is reported to impair CFTR mRNA splicing. We present three lines of evidence that argue against the pathogenicity of this variant. First, its allelic frequency in the Italian population was 0.4%. Even considering the lowest value in the confidence interval we would expect 10% of Italian CF patients to be heterozygotes for this variant, whereas it has been reported only in one patient (0.04% of Italian CF patients). Second, expression of the 621+3 A>G variant in HeLa cells using a hybrid minigene showed that 39.5+/-1.1% of transcripts were correctly spliced, indicating that its effects on mRNA splicing are similar to those of the CFTR intron 8 5T variant, associated with congenital bilateral absence of vas deferens (CBAVD), but not with CF. Third, we have identified an asymptomatic individual who harbored the 621+3 A>G variant in trans with the Q552X mutation. Because 621+3 A>G is often included in population-screening programs, this information is critical to provide adequate counseling to patients. Further work should be aimed at investigating whether this variant may have a role in CBAVD or atypical CF.

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103 4 Tzetis, M., Efthymiadou, A., Doudounakis, S. & Kanavakis, E. Qualitative and quantitative analysis of mRNA associated with four putative splicing mutations (621+3A4G, 2751+2T-4A, 296+1G-4C, 1717-9T-4C-D565G) and one nonsense mutation (E822X) in the CFTR gene. Login to comment

[hide] Mutations that permit residual CFTR function delay... Respir Res. 2010 Oct 8;11:140. Green DM, McDougal KE, Blackman SM, Sosnay PR, Henderson LB, Naughton KM, Collaco JM, Cutting GR
Mutations that permit residual CFTR function delay acquisition of multiple respiratory pathogens in CF patients.
Respir Res. 2010 Oct 8;11:140., [PMID:20932301]

Abstract [show]
BACKGROUND: Lung infection by various organisms is a characteristic feature of cystic fibrosis (CF). CFTR genotype effects acquisition of Pseudomonas aeruginosa (Pa), however the effect on acquisition of other infectious organisms that frequently precede Pa is relatively unknown. Understanding the role of CFTR in the acquisition of organisms first detected in patients may help guide symptomatic and molecular-based treatment for CF. METHODS: Lung infection, defined as a single positive respiratory tract culture, was assessed for 13 organisms in 1,381 individuals with CF. Subjects were divided by predicted CFTR function: 'Residual': carrying at least one partial function CFTR mutation (class IV or V) and 'Minimal' those who do not carry a partial function mutation. Kaplan-Meier estimates were created to assess CFTR effect on age of acquisition for each organism. Cox proportional hazard models were performed to control for possible cofactors. A separate Cox regression was used to determine whether defining infection with Pa, mucoid Pa or Aspergillus (Asp) using alternative criteria affected the results. The influence of severity of lung disease at the time of acquisition was evaluated using stratified Cox regression methods by lung disease categories. RESULTS: Subjects with 'Minimal' CFTR function had a higher hazard than patients with 'Residual' function for acquisition of 9 of 13 organisms studied (HR ranging from 1.7 to 3.78 based on the organism studied). Subjects with minimal CFTR function acquired infection at a younger age than those with residual function for 12 of 13 organisms (p-values ranging: < 0.001 to 0.017). Minimal CFTR function also associated with younger age of infection when 3 alternative definitions of infection with Pa, mucoid Pa or Asp were employed. Risk of infection is correlated with CFTR function for 8 of 9 organisms in patients with good lung function (>90%ile) but only 1 of 9 organisms in those with poorer lung function (<50%ile). CONCLUSIONS: Residual CFTR function correlates with later onset of respiratory tract infection by a wide spectrum of organisms frequently cultured from CF patients. The protective effect conferred by residual CFTR function is diminished in CF patients with more advanced lung disease.

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74 For Pa, the hazard ratio Table 1 Classification of CFTR alleles Category Mutation Specific mutations Class I Defective Protein Synthesis (nonsense, frameshift, aberrant splicing) 1078delT, 1154 insTC, 1525-2A > G, 1717-1G > A, 1898+1G > A, 2184delA, 2184 insA, 3007delG, 3120+1G > A, 3659delC, 3876delA, 3905insT, 394delTT, 4010del4, 4016insT, 4326delTC, 4374+1G > T, 441delA, 556delA, 621+1G > T, 621-1G > T, 711+1G > T, 875+1G > C, E1104X, E585X, E60X, E822X, G542X, G551D/R553X, Q493X, Q552X, Q814X, R1066C, R1162X, R553X, V520F, W1282X, Y1092X Class II Abnormal Processing and Trafficking A559T, D979A, ΔF508, ΔI507, G480C, G85E, N1303K, S549I, S549N, S549R Class III Defective Channel Regulation/Gating G1244E, G1349D, G551D, G551S, G85E, H199R, I1072T, I48T, L1077P, R560T, S1255P, S549 (R75Q) Class IV Decreased Channel Conductance A800G, D1152H, D1154G, D614G, delM1140, E822K, G314E, G576A, G622D, G85E, H620Q, I1139V, I1234V, L1335P, M1137V, P67L, R117C, R117P, R117H, R334W, R347H, R347P, R347P/ R347H, R792G, S1251N, V232D Class V Reduced Synthesis and/or Trafficking 2789+5G > A, 3120G > A, 3272-26A > G, 3849+10kbC > T, 5T variant, 621+3A > G, 711+3A > G, A445E, A455E, IVS8 poly T, P574H was increased 3 fold for those with 'Minimal` function when compared to those with 'Residual` function. Login to comment

[hide] Quantitative methods for the analysis of CFTR tran... J Cyst Fibros. 2004 Aug;3 Suppl 2:17-23. Amaral MD, Clarke LA, Ramalho AS, Beck S, Broackes-Carter F, Rowntree R, Mouchel N, Williams SH, Harris A, Tzetis M, Steiner B, Sanz J, Gallati S, Nissim-Rafinifa M, Kerem B, Hefferon T, Cutting GR, Goina E, Pagani F
Quantitative methods for the analysis of CFTR transcripts/splicing variants.
J Cyst Fibros. 2004 Aug;3 Suppl 2:17-23., [PMID:15463919]

Abstract [show]
In cystic fibrosis (CF), transcript analysis and quantification are important for diagnosis, prognosis and also as surrogate markers for some therapies including gene therapy. Classical RNA-based methods require significant expression levels in target samples for appropriate analysis, thus PCR-based methods are evolving towards reliable quantification. Various protocols for the quantitative analysis of CFTR transcripts (including those resulting from splicing variants) are described and discussed here.

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74 Example: E822X Nasal epithelial cells are collected as described [6] from individuals with mutation E822X (G>T at 2596), non-CF controls and heterozygotes for the polymorphism R668C, and mRNA extracted. Login to comment
81 E822X RNA samples with E822X are reverse-transcribed with an initial primer set spanning exons 13 to 14a. Login to comment
85 M.D. Amaral et al. / Journal of Cystic Fibrosis 3 (2004) 17-23 19 E822 (G at 2596, E822X: G>T at 2596) creates a restriction site for Hph1, whereas the mutant transcript remains intact. Login to comment

[hide] Atypical 5' splice sites cause CFTR exon 9 to be v... Am J Hum Genet. 2002 Aug;71(2):294-303. Epub 2002 Jun 13. Hefferon TW, Broackes-Carter FC, Harris A, Cutting GR
Atypical 5' splice sites cause CFTR exon 9 to be vulnerable to skipping.
Am J Hum Genet. 2002 Aug;71(2):294-303. Epub 2002 Jun 13., [PMID:12068373]

Abstract [show]
The molecular basis of the skipping of constitutive exons in many messenger RNAs is not fully understood. A well-studied example is exon 9 of the human cystic fibrosis transmembrane conductance regulator gene (CFTR), in which an abbreviated polypyrimidine tract between the branch point A and the 3' splice site is associated with increased exon skipping and disease. However, many exons, both in CFTR and in other genes and have short polypyrimidine tracts in their 3' splice sites, yet they are not skipped. Inspection of the 5' splice sites immediately up- and downstream of exon 9 revealed deviations from consensus sequence, so we hypothesized that this exon may be inherently vulnerable to skipping. To test this idea, we constructed a CFTR minigene and replicated exon 9 skipping associated with the length of the polypyrimidine tract upstream of exon 9. We then mutated the flanking 5' splice sites and determined the effect on exon skipping. Conversion of the upstream 5' splice site to consensus by replacing a pyrimidine at position +3 with a purine resulted in increased exon skipping. In contrast, conversion of the downstream 5' splice site to consensus by insertion of an adenine at position +4 resulted in a substantial reduction in exon 9 skipping, regardless of whether the upstream 5' splice site was consensus or not. These results suggested that the native downstream 5' splice site plays an important role in CFTR exon 9 skipping, a hypothesis that was supported by data from sheep and mouse genomes. Although CFTR exon 9 in sheep is preceded by a long polypyrimidine tract (Y(14)), it skips exon 9 in vivo and has a nonconsensus downstream 5' splice site identical to that in humans. On the other hand, CFTR exon 9 in mice is preceded by a short polypyrimidine tract (Y(5)) but is not skipped in vivo. Its downstream 5' splice site differs from that in humans by a 2-nt insertion, which, when introduced into the human CFTR minigene, abolished exon 9 skipping. Taken together, these observations place renewed emphasis on deviations at 5' splice sites in nucleotides other than the invariant GT, particularly when such changes are found in conjunction with other altered splicing sequences, such as a shortened polypyrimidine tract. Thus, careful inspection of entire 5' splice sites may identify constitutive exons that are vulnerable to skipping.

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237 Hum Mol Genet 6:85-90 Tzetis M, Efthymiadou A, Doudounakis S, Kanavakis E (2001) Qualitative and quantitative analysis of mRNA associated with four putative splicing mutations (621ϩ3ArG, 2751ϩ2TrA, 296ϩ1GrC, 1717-9TrC- D565G) and one nonsense mutation (E822X) in the CFTR gene. Login to comment
238 Hum Mol Genet 6:85-90 Tzetis M, Efthymiadou A, Doudounakis S, Kanavakis E (2001) Qualitative and quantitative analysis of mRNA associated with four putative splicing mutations (621af9;3ArG, 2751af9;2TrA, 296af9;1GrC, 1717afa;9TrCafa; D565G) and one nonsense mutation (E822X) in the CFTR gene. Login to comment

[hide] Improving newborn screening for cystic fibrosis us... Genet Med. 2015 Feb 12. doi: 10.1038/gim.2014.209. Baker MW, Atkins AE, Cordovado SK, Hendrix M, Earley MC, Farrell PM
Improving newborn screening for cystic fibrosis using next-generation sequencing technology: a technical feasibility study.
Genet Med. 2015 Feb 12. doi: 10.1038/gim.2014.209., [PMID:25674778]

Abstract [show]
Purpose:Many regions have implemented newborn screening (NBS) for cystic fibrosis (CF) using a limited panel of cystic fibrosis transmembrane regulator (CFTR) mutations after immunoreactive trypsinogen (IRT) analysis. We sought to assess the feasibility of further improving the screening using next-generation sequencing (NGS) technology.Methods:An NGS assay was used to detect 162 CFTR mutations/variants characterized by the CFTR2 project. We used 67 dried blood spots (DBSs) containing 48 distinct CFTR mutations to validate the assay. NGS assay was retrospectively performed on 165 CF screen-positive samples with one CFTR mutation.Results:The NGS assay was successfully performed using DNA isolated from DBSs, and it correctly detected all CFTR mutations in the validation. Among 165 screen-positive infants with one CFTR mutation, no additional disease-causing mutation was identified in 151 samples consistent with normal sweat tests. Five infants had a CF-causing mutation that was not included in this panel, and nine with two CF-causing mutations were identified.Conclusion:The NGS assay was 100% concordant with traditional methods. Retrospective analysis results indicate an IRT/NGS screening algorithm would enable high sensitivity, better specificity and positive predictive value (PPV). This study lays the foundation for prospective studies and for introducing NGS in NBS laboratories.Genet Med advance online publication 12 February 2015Genetics in Medicine (2015); doi:10.1038/gim.2014.209.

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15 Correspondence: Mei W. Baker (mwbaker@wisc.edu) Improving newborn screening for cystic fibrosis using next-generation sequencing technology: a technical feasibility study Mei W. Baker, MD1,2 , Anne E. Atkins, MPH2 , Suzanne K. Cordovado, PhD3 , Miyono Hendrix, MS3 , Marie C. Earley, PhD3 and Philip M. Farrell, MD, PhD1,4 Table 1ߒ CF-causing or varying consequences mutations in the MiSeqDx IUO Cystic Fibrosis System c.1521_1523delCTT (F508del) c.2875delG (3007delG) c.54-5940_273ߙ+ߙ10250del21kb (CFTRdele2,3) c.3909C>G (N1303K) c.3752G>A (S1251N) Mutations that cause CF when combined with another CF-causing mutation c.1624G>T (G542X) c.2988ߙ+ߙ1G>A (3120ߙ+ߙ1G->A) c.3964-78_4242ߙ+ߙ577del (CFTRdele22,23) c.613C>T (P205S) c.1021T>C (S341P) c.948delT (1078delT) c.2988G>A (3120G->A) c.328G>C (D110H) c.200C>T (P67L) c.1397C>A (S466X(C>A)) c.1022_1023insTC (1154insTC) c.2989-1G>A (3121-1G->A) c.3310G>T (E1104X) c.3937C>T (Q1313X) c.1397C>G (S466X(C>G)) c.1081delT (1213delT) c.3140-26A>G (3272-26A->G) c.1753G>T (E585X) c.658C>T (Q220X) c.1466C>A (S489X) c.1116ߙ+ߙ1G>A (1248ߙ+ߙ1G->A) c.3528delC (3659delC) c.178G>T (E60X) c.115C>T (Q39X) c.1475C>T (S492F) c.1127_1128insA (1259insA) c.3659delC (3791delC) c.2464G>T (E822X) c.1477C>T (Q493X) c.1646G>A (S549N) c.1209ߙ+ߙ1G>A (1341ߙ+ߙ1G->A) c.3717ߙ+ߙ12191C>T (3849ߙ+ߙ10kbC->T) c.2491G>T (E831X) c.1573C>T (Q525X) c.1645A>C (S549R) c.1329_1330insAGAT (1461ins4) c.3744delA (3876delA) c.274G>A (E92K) c.1654C>T (Q552X) c.1647T>G (S549R) c.1393-1G>A (1525-1G->A) c.3773_3774insT (3905insT) c.274G>T (E92X) c.2668C>T (Q890X) c.2834C>T (S945L) c.1418delG (1548delG) c.262_263delTT (394delTT) c.3731G>A (G1244E) c.292C>T (Q98X) c.1013C>T (T338I) c.1545_1546delTA (1677delTA) c.3873ߙ+ߙ1G>A (4005ߙ+ߙ1G->A) c.532G>A (G178R) c.3196C>T (R1066C) c.1558G>T (V520F) c.1585-1G>A (1717-1G->A) c.3884_3885insT (4016insT) c.988G>T (G330X) c.3197G>A (R1066H) c.3266G>A (W1089X) c.1585-8G>A (1717-8G->A) c.273ߙ+ߙ1G>A (405ߙ+ߙ1G->A) c.1652G>A (G551D) c.3472C>T (R1158X) c.3611G>A (W1204X) c.1679ߙ+ߙ1.6kbA>G (1811ߙ+ߙ1.6kbA->G) c.274-1G>A (406-1G->A) c.254G>A (G85E) c.3484C>T (R1162X) c.3612G>A (W1204X) c.1680-1G>A (1812-1G->A) c.4077_4080delTGTTinsAA (4209TGTT->AA) c.2908G>C (G970R) c.349C>T (R117C) c.3846G>A (W1282X) c.1766ߙ+ߙ1G>A (1898ߙ+ߙ1G->A) c.4251delA (4382delA) c.595C>T (H199Y) c.1000C>T (R334W) c.1202G>A (W401X) c.1766ߙ+ߙ3A>G (1898ߙ+ߙ 3A->G) c.325_327delTATinsG (457TAT->G) c.1007T>A (I336K) c.1040G>A (R347H) c.1203G>A (W401X) c.2012delT (2143delT) c.442delA (574delA) c.1519_1521delATC (I507del) c.1040G>C (R347P) c.2537G>A (W846X) c.2051_2052delAAinsG (2183AA->G) c.489ߙ+ߙ1G>T (621ߙ+ߙ 1G->T) c.2128A>T (K710X) c.1055G>A (R352Q) c.3276C>A (Y1092X (C>A)) c.2052delA (2184delA) c.531delT (663delT) c.3194T>C (L1065P) c.1657C>T (R553X) c.3276C>G (Y1092X (C>G)) c.2052_2053insA (2184insA) c.579ߙ+ߙ1G>T (711ߙ+ߙ 1G->T) c.3230T>C (L1077P) c.1679G>A (R560K) c.366T>A (Y122X) c.2175_2176insA (2307insA) c.579ߙ+ߙ3A>G (711ߙ+ߙ 3A->G) c.617T>G (L206W) c.1679G>C (R560T) - c.2215delG (2347delG) c.579ߙ+ߙ5G>A (711ߙ+ߙ 5G->A) c.1400T>C (L467P) c.2125C>T (R709X) - c.2453delT (2585delT) c.580-1G>T (712-1G->T) c.2195T>G (L732X) c.223C>T (R75X) - c.2490ߙ+ߙ1G>A (2622ߙ+ߙ1G->A) c.720_741delAGGGAG AATGATGATGAAGTAC (852del22) c.2780T>C (L927P) c.2290C>T (R764X) - c.2583delT (2711delT) c.1364C>A (A455E) c.3302T>A (M1101K) c.2551C>T (R851X) - c.2657ߙ+ߙ5G>A (2789ߙ+ߙ5G->A) c.1675G>A (A559T) c.1A>G (M1V) c.3587C>G (S1196X) - Mutations/variants that were validated in this study are in bold. CF, cystic fibrosis. Table 1ߒ Continued on next page reduce carrier detection and potentially improve the positive predictive value (PPV), the NBS goals of equity and the highest possible sensitivity become more difficult to achieve. Login to comment

[hide] The improvement of the best practice guidelines fo... Eur J Hum Genet. 2015 May 27. doi: 10.1038/ejhg.2015.99. Girardet A, Viart V, Plaza S, Daina G, De Rycke M, Des Georges M, Fiorentino F, Harton G, Ishmukhametova A, Navarro J, Raynal C, Renwick P, Saguet F, Schwarz M, SenGupta S, Tzetis M, Roux AF, Claustres M
The improvement of the best practice guidelines for preimplantation genetic diagnosis of cystic fibrosis: toward an international consensus.
Eur J Hum Genet. 2015 May 27. doi: 10.1038/ejhg.2015.99., [PMID:26014425]

Abstract [show]
Cystic fibrosis (CF) is one of the most common indications for preimplantation genetic diagnosis (PGD) for single gene disorders, giving couples the opportunity to conceive unaffected children without having to consider termination of pregnancy. However, there are no available standardized protocols, so that each center has to develop its own diagnostic strategies and procedures. Furthermore, reproductive decisions are complicated by the diversity of disease-causing variants in the CFTR (cystic fibrosis transmembrane conductance regulator) gene and the complexity of correlations between genotypes and associated phenotypes, so that attitudes and practices toward the risks for future offspring can vary greatly between countries. On behalf of the EuroGentest Network, eighteen experts in PGD and/or molecular diagnosis of CF from seven countries attended a workshop held in Montpellier, France, on 14 December 2011. Building on the best practice guidelines for amplification-based PGD established by ESHRE (European Society of Human Reproduction and Embryology), the goal of this meeting was to formulate specific guidelines for CF-PGD in order to contribute to a better harmonization of practices across Europe. Different topics were covered including variant nomenclature, inclusion criteria, genetic counseling, PGD strategy and reporting of results. The recommendations are summarized here, and updated information on the clinical significance of CFTR variants and associated phenotypes is presented.European Journal of Human Genetics advance online publication, 27 May 2015; doi:10.1038/ejhg.2015.99.

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79 (unknown) Q39X c.115C4T p.Gln39* P67L c.200C4T p.Pro67Leu R75X c.223C4T p.Arg75* 405+1G4A c.273+1G4A 406-1G4A c.274-1G4A E92X c.274G4T p.Glu92* E92K c.274G4A p.Glu92Lys Q98X c.292C4T p.Gln98* 457TAT4G c.325_327delTATinsG p.Tyr109Glyfs*4 D110H c.328G4C p.Asp110His R117C c.349C4T p.Arg117Cys Y122X c.366 T4A p.Tyr122* 574delA c.442delA p.Ile148Leufs*5 444delA c.313delA p.Ile105Serfs*2 663delT c.531delT p.Ile177Metfs*12 G178R c.532G4A p.Gly178Arg 711+3 A4G c.579+3 A4G 711+5G4A c.579+5G4A 712-1G4T c.580-1G4T H199Y c.595C4T p.His199Tyr P205S c.613C4T p.Pro205Ser L206W c.617 T4G p.Leu206Trp Q220X c.658C4T p.Gln220* 852del22 c.720_741delAGGGAGAAT GATGATGAAGTAC p.Gly241Glufs*13 1078delT c.948delT p.Phe316Leufs*12 G330X c.988G4T p.Gly330* Table 1 (Continued ) HGVS nomenclature Legacy name cDNA nucleotide name Protein name R334W c.1000C4T p.Arg334Trp I336K c.1007 T4A p.Ile336Lys T338I c.1013C4T p.Thr338Ile 1154insTC c.1021_1022dupTC p.Phe342Hisfs*28 S341P c.1021 T4C p.Ser341Pro R347H c.1040G4A p.Arg347His 1213delT c.1081delT p.Trp361Glyfs*8 1248+1G4A c.1116+1G4A 1259insA c.1130dupA p.Gln378Alafs*4 W401X(TAG) c.1202G4A p.Trp401* W401X(TGA) c.1203G4A p.Trp401* 1341+1G4A c.1209+1G4A 1461ins4 c.1329_1330insAGAT p.Ile444Argfs*3 1525-1G4A c.1393-1G4A S466X c.1397C4A or c.1397C4G p.Ser466* L467P c.1400 T4C p.Leu467Pro S489X c.1466C4A p.Ser489* S492F c.1475C4T p.Ser492Phe 1677delTA c.1545_1546delTA p.Tyr515* V520F c.1558G4T p.Val520Phe 1717-1G4A c.1585-1G4A 1717-8G4A c.1585-8G4A S549R c.1645 A4C p.Ser549Arg S549N c.1646G4A p.Ser549Asn S549R c.1647 T4G p.Ser549Arg Q552X c.1654C4T p.Gln552* A559T c.1675G4A p.Ala559Thr 1811+1.6kbA4G c.1680-886 A4G 1812-1G4A c.1680-1G4A R560K c.1679G4A p.Arg560Lys E585X c.1753G4T p.Glu585* 1898+3 A4G c.1766+3 A4G 2143delT c.2012delT p.Leu671* 2184insA c.2052_2053insA p.Gln685Thrfs*4 2184delA c.2052delA p.Lys684Asnfs*38 R709X c.2125C4T p.Arg709* K710X c.2128 A4T p.Lys710* 2307insA c.2175dupA p.Glu726Argfs*4 L732X c.2195 T4G p.Leu732* 2347delG c.2215delG p.Val739Tyrfs*16 R764X c.2290C4T p.Arg764* 2585delT c.2453delT p.Leu818Trpfs*3 E822X c.2464G4T p.Glu822* 2622+1G4A c.2490+1G4A E831X c.2491G4T p.Glu831* W846X c.2537G4A p.Trp846* W846X (2670TGG4TGA) c.2538G4A p.Trp846* R851X c.2551C4T p.Arg851* 2711delT c.2583delT p.Phe861Leufs*3 S945L c.2834C4T p.Ser945Leu 2789+2insA c.2657+2_2657+3insA Q890X c.2668C4T p.Gln890* L927P c.2780 T4C p.Leu927Pro 3007delG c.2875delG p.Ala959Hisfs*9 G970R c.2908G4C p.Gly970Arg 3120G4A c.2988G4A function variants that cause CF disease when paired together; (ii) variants that retain residual CFTR function and are compatible with milder phenotypes such as CFTR-RD; (iii) variants with no clinical consequences; and (iv) variants of unproven or uncertain clinical relevance. Login to comment