ABCMdb

PMID: 18685558

Dequeker E, Stuhrmann M, Morris MA, Casals T, Castellani C, Claustres M, Cuppens H, des Georges M, Ferec C, Macek M, Pignatti PF, Scheffer H, Schwartz M, Witt M, Schwarz M, Girodon E
Best practice guidelines for molecular genetic diagnosis of cystic fibrosis and CFTR-related disorders--updated European recommendations.
Eur J Hum Genet. 2009 Jan;17(1):51-65. Epub 2008 Aug 6., [PubMed]

Sentences

No. Mutations Sentence Comment

35 ABCC7 p.Gly551Asp ABCC7 p.Trp1282* ABCC7 p.Arg553* ABCC7 p.Arg1283Met CFTR mutations may Table 1 Methods for CFTR gene mutation detection most frequently used in Europe Methods for the detection of known mutations Mutations detected Advantages Limits and pitfalls Heteroduplex analysis (strictly speaking a scanning method) Mainly F508del and I507del Other microinsertions/deletions (2 bp minimum): 394delTT (Northern Europe), 1677delTA (Black Sea countries), 1609delCA (Spain) Simple and rapid Migration pattern not specific for a given mutation Restriction enzyme analysis (restriction sites can be natural or created by the use of modified primers) Mainly specific individual mutations Possibly a small number of mutations can be combined in one assay Simple and rapid Useful for cascade carrier testing in case of rare mutations Not specific, especially if site abolition (eg, G551D and R553X abolish the same Hinc II site, and W1282X and R1283M the same Mnl I site) Reverse dot blot hybridization Up to 20 mutations per multiplex Appropriate for large series Innogenetics (Inno LiPA)a 36 mutations Good specificity ARMS (amplification refractory mutation system) Up to 20 mutations Appropriate for large series Design of primers is difficult Results are based on the absence of PCR product Tepnel (Elucigene)a 28-30 mutations Good specificity OLA (oligonucleotide ligation assay) Appropriate for large series Abbott Molecular (Cystic Fibrosis Genotyping Assay)a 32 mutations Good specificity Methods for the detection of unknown mutations DGGE (denaturing gradient gel electrophoresis) DGGE, DHPLC, SSCP and Sequencing: High sensitivity (495%) Difficult to set up; difficult automation Can miss isostable mutations in the homozygous state DHPLC (denaturing high performance liquid chromatography) Aiming to detect all mutations of small bp in the coding regions and intronic boundaries High sensitivity (495%) Generally miss homozygous mutations Need sequencing of polymorphism-rich regions SSCP (single strand conformation polymorphism) Simple and rapid to set up Sensitivity 80-85% Sequencing (as a first-line method or confirmation after a scanning technique) Close to 100% sensitivity Quantitative fluorescent multiplex PCR MLPA (multiple ligation-dependent probe amplification) Aiming to detect deletions, insertions, and duplications All coding regions Simple and rapid Sensitive to extraction methods Duplications may be difficult to evidence a Commercially available methods are indicated in italics be missed by scanning techniques, especially when homozygous, and even direct sequencing cannot identify 100% of mutations. Login to comment 144 ABCC7 p.Gly551Asp ABCC7 p.Arg117His ABCC7 p.Trp1282* ABCC7 p.Arg553* ABCC7 p.Arg347Pro ABCC7 p.Asn1303Lys ABCC7 p.Gly542* ABCC7 p.Arg74Trp ABCC7 p.Gly622Asp ABCC7 p.Phe508Cys ABCC7 p.Arg668Cys ABCC7 p.Ile506Val ABCC7 p.Leu997Phe ABCC7 p.Arg170His ABCC7 p.Val938Gly ABCC7 p.Val562Ile ABCC7 p.Ile125Thr A (T)5 variant can either be associated with (TG)11, (TG)12, (TG)13, and rarely (TG)15 repeats.74 When (T)5 is found in diagnostic testing, for example, for CBAVD or atypical presentation, determination of Table 4 Classification of CFTR mutations with regard to their potential for causing disease Mutation group Examples CF-causing F508del Mainly nonsense, frameshift, splicing (invariant dinucleotide): G542X, R553X, W1282X, 2183AA4G, 3659delC, 1717-1G4A, 3120+1G4A Missense that severely affects CFTR synthesis or function: G551D, N1303K, R347P 2789+5G4A, 3849+10kbC4T, 3272-26A4G, L206Wa , D1152Ha , (TG)13(T)5a CFTR-related disorders associated L206Wa , D1152Ha , (TG)13(T)5a [R117H;(T)7], (TG)12(T)5, L997F, V562I, [R668C;G576A;D443Y], [R74W;D1270N] (TG)11(T)5b , S1235Rb No clinical consequences 875+40A4G, M470V (1540A4G), I506V (1648A4G), F508C (1655T4G), 1716G4A, 2694T4G, 4002A4G, 2752-15G4C (TG)11(T)5b , S1235Rb Unproven or uncertain clinical relevance Mainly missense mutations G622D, R170H, V938G, I125T Putative splice mutations: 406-6T4C, 2752-26A4G, 3601-17T4C Only a fraction of mutations and patients have been characterized in detail and, with the exception of frequent mutations, only small numbers of patients have been available for the study of most mutations. Login to comment 149 ABCC7 p.Ile148Thr I148T Was initially described as a frequent CF-causing mutation. Login to comment 151 ABCC7 p.Arg117His ABCC7 p.Ile148Thr I148T should not be routinely screened for and is currently being removed from the panels of commercial assays.25 R117H Can be found in cis with IVS8 (T)5 or (T)7. Login to comment 152 ABCC7 p.Arg117His ABCC7 p.Arg117His [R117H;(T)5] is considered a mild CF-causing complex allele, whereas [R117H;(T)7] is considered more as a CFTR-RD mutation. Login to comment 153 ABCC7 p.Arg117His In neonatal screening programmes, the high frequency of R117H in newborns with elevated immunoreactive trypsinaemia78 has raised the question of its penetrance and its clinical significance for genetic counselling. Login to comment 154 ABCC7 p.Arg117His ABCC7 p.Arg117His So far, children who are compound heterozygous for [R117H;(T)7] and a severe CF-causing mutation have shown no clinical signs of CF.78 Given these observations, identification of R117H in trans with F508del in neonates should be completed by IVS8 poly(T) testing. Login to comment 155 ABCC7 p.Arg117His If R117H is in cis with (T)7, genetic counselling should be reassuring. Login to comment