ABCMdb

ABCC7 p.Ser912Leu

ClinVar:	c.2736G>A , p.Ser912= ? , Uncertain significance c.2735C>A , p.Ser912* ? , not provided c.2735C>T , p.Ser912Leu N , Benign
CF databases:	c.2735C>A , p.Ser912* D , CF-causing c.2735C>T , p.Ser912Leu (CFTR1) ? , The nucleotide change C->T at position 2876 in exon 15 results in a replacement of a serine for leucine at position 912.
Predicted by SNAP2:	A: D (71%), C: D (80%), D: D (80%), E: D (85%), F: D (75%), G: D (80%), H: D (75%), I: D (80%), K: D (85%), L: D (80%), M: D (80%), N: D (75%), P: D (91%), Q: D (75%), R: D (85%), T: D (71%), V: D (75%), W: D (91%), Y: D (80%),
Predicted by PROVEAN:	A: N, C: N, D: N, E: N, F: N, G: N, H: N, I: N, K: N, L: N, M: N, N: N, P: N, Q: N, R: N, T: N, V: N, W: N, Y: N,

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[hide] Gender-sensitive association of CFTR gene mutation... Mol Hum Reprod. 2005 Aug;11(8):607-14. Epub 2005 Aug 26. Morea A, Cameran M, Rebuffi AG, Marzenta D, Marangon O, Picci L, Zacchello F, Scarpa M
Gender-sensitive association of CFTR gene mutations and 5T allele emerging from a large survey on infertility.
Mol Hum Reprod. 2005 Aug;11(8):607-14. Epub 2005 Aug 26., [PMID:16126774]

Abstract [show]
Human infertility in relation to mutations affecting the cystic fibrosis transmembrane regulator (CFTR) gene has been investigated by different authors. The role of additional variants, such as the possible forms of the thymidine allele (5T, 7T and 9T) of the acceptor splice site of intron 8, has in some instances been considered. However, a large-scale analysis of the CFTR gene and number of thymidine residues, alone and in combination, in the two sexes had not yet been addressed. This was the aim of this study. Two groups were compared, a control group of 20,532 subjects being screened for perspective reproduction, and the patient group represented by 1854 idiopathically infertile cases. Analyses involved PCR-based CFTR mutations assessment, reverse dot-blot IVS8-T polymorphism analyses, denaturing gradient gel electrophoresis (DGGE) and DNA sequencing. The expected 5T increase in infertile men was predominantly owing to the 5/9 genotypic class. The intrinsic rate of 5T fluctuated only slightly among groups, but some gender-related differences arose when comparing their association. Infertile men showed a significantly enriched 5T + CFTR mutation co-presence, distributed in the 5/9 and 5/7 classes. In contrast, females, from both the control and the infertile groups, showed a trend towards a pronounced reduction of such association. The statistical significance of the difference between expected and observed double occurrence of 5T + CFTR traits in women suggests, in line with other reports in the literature, a possible survival-hampering effect. Moreover, regardless of the 5T status, CFTR mutations appear not to be involved in female infertility. These results underline the importance of (i) assessing large sample populations and (ii) considering separately the two genders, whose genotypically opposite correlations with these phenomena may otherwise tend to mask each other.

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76 This test involved nine subjects from the infertile group, revealing the occurrence of the following rare mutations: E217G, T1054A, W356X, D443Y and 3667insTC in males and L997F and R297Q in females and 29 subjects from the control, in which we found: A1009T, D110Y, E826K, G1069R, G1130A, G194V, I556V, L320F, M348K, M82V, P1290T, R117C, R352W, R74W, S42F, S660T, S911R, S912L, T1086A, T582S, V920L and Y89C. Login to comment

[hide] Extensive sequencing of the CFTR gene: lessons lea... Hum Genet. 2005 Dec;118(3-4):331-8. Epub 2005 Sep 28. McGinniss MJ, Chen C, Redman JB, Buller A, Quan F, Peng M, Giusti R, Hantash FM, Huang D, Sun W, Strom CM
Extensive sequencing of the CFTR gene: lessons learned from the first 157 patient samples.
Hum Genet. 2005 Dec;118(3-4):331-8. Epub 2005 Sep 28., [PMID:16189704]

Abstract [show]
Cystic fibrosis (CF) is one of the most common monogenic diseases affecting Caucasians and has an incidence of approximately 1:3,300 births. Currently recommended screening panels for mutations in the responsible gene (CF transmembrane regulator gene, CFTR) do not detect all disease-associated mutations. Our laboratory offers extensive sequencing of the CFTR (ABCC7) gene (including the promoter, all exons and splice junction sites, and regions of selected introns) as a clinical test to detect mutations which are not found with conventional screening. The objective of this report is to summarize the findings of extensive CFTR sequencing from our first 157 consecutive patient samples. In most patients with classic CF symptoms (18/24, 75%), extensive CFTR sequencing confirmed the diagnosis by finding two disease-associated mutations. In contrast, only 5 of 75 (7%) patients with atypical CF had been identified with two CFTR mutations. A diagnosis of CF was confirmed in 10 of 17 (58%) newborns with either positive sweat chloride readings or positive immunoreactive trypsinogen (IRT) screen results. We ascertained ten novel sequence variants that are potentially disease-associated: two deletions (c.1641AG>T, c.2949_2853delTACTC), seven missense mutations (p.S158T, p.G451V, p.K481E, p.C491S, p.H949L, p.T1036N, p.F1099L), and one complex allele ([p.356_A357del; p.358I]). We ascertained three other apparently novel complex alleles. Finally, several patients were found to carry partial CFTR gene deletions. In summary, extensive CFTR gene sequencing can detect rare mutations which are not found with other screening and diagnostic tests, and can thus establish a definitive diagnosis in symptomatic patients with previously negative results. This enables carrier detection and prenatal diagnosis in additional family members.

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72 The two deletions Table 2 Atypical CF or nonclassic patients in whom extensive sequencing revealed two CFTR mutations Patient Genotype Phenotype Sex Age (years) Sweat chloride concentration (mmol/l) 1 p.S912L/DF508 Chronic lung and sinus disease F 52 Not done 2 p.R1070W/p.N1303K Recurrent respiratory infections F 4.5 2X intermediate 3 p.G551D/c.2789+2 InsA Pancreatic insufficiency, little lung involvement F 50 92, 96 4 c.3849+10kb C>T/p.L732X Failure to thrive, chronic cough, chronic sinusitis M 5.5 70,73 5 p.W1282X/p.R170H Chronic pancreatitis, CBVAD M 44 Borderline (c.1641 AG>T, and c.2949-2953 del TACTC) are expected to be severe disease-associated mutations, since they change the CFTR reading frame; the two patients harboring these novel deletions had a diagnosis of CF with elevated sweat chloride levels and carried a second, previously described, CF mutation. Login to comment

[hide] Cystic fibrosis transmembrane conductance regulato... Cancer. 2010 Jan 1;116(1):203-9. McWilliams RR, Petersen GM, Rabe KG, Holtegaard LM, Lynch PJ, Bishop MD, Highsmith WE Jr
Cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations and risk for pancreatic adenocarcinoma.
Cancer. 2010 Jan 1;116(1):203-9., 2010-01-01 [PMID:19885835]

Abstract [show]
BACKGROUND: Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene are common in white persons and are associated with pancreatic disease. The purpose of this case-control study was to determine whether CFTR mutations confer a higher risk of pancreatic cancer. METHODS: In a case-control study, the authors compared the rates of 39 common cystic fibrosis-associated CFTR mutations between 949 white patients with pancreatic adenocarcinoma and 13,340 white controls from a clinical laboratory database for prenatal testing for CFTR mutations. The main outcome measure was the CFTR mutation frequency in patients and controls. RESULTS: Overall, 50 (5.3%) of 949 patients with pancreatic cancer carried a common CFTR mutation versus 510 (3.8%) of 13,340 controls (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.04-1.89; P = .027). Among patients who were younger when their disease was diagnosed (<60 years), the carrier frequency was higher than in controls (OR, 1.82; 95% CI, 1.14-2.94; P = .011). In patient-only analyses, the presence of a mutation was associated with younger age (median 62 vs 67 years; P = .034). In subgroups, the difference was seen only among ever-smokers (60 vs 65 years, P = .028). Subsequent sequencing analysis of the CFTR gene detected 8 (16%) compound heterozygotes among the 50 patients initially detected to have 1 mutation. CONCLUSIONS: Carrying a disease-associated mutation in CFTR is associated with a modest increase in risk for pancreatic cancer. Those affected appear to be diagnosed at a younger age, especially among smokers. Clinical evidence of antecedent pancreatitis was uncommon among both carriers and noncarriers of CFTR mutations.

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95 S42F has been described in 1 Italian CF patient.25 E528E is a synonymous polymorphism involving the last base pair in exon 10 (1716 G > A), which has been reported to affect splicing, but has not been linked to severe pulmonary disease.26 S912L is thought to be a neutral variant (serine for a leucine), unless in cis position to another mutation.27 The F1052V missense mutation is a variant with a modest effect, with normal or near-normal sweat chloride tests in combination with other mild variants.28,29 N1088S is a novel mutation that substitutes asparagine for a serine amino acid, both positively charged, and its functionality is unclear. Login to comment
103 Compound Heterozygotes Among Pancreatic Cancer Cases CFTR Mutations Sex Age at Diagnosis, y Ever/Never Smoker Family History of Pancreatic Cancer Pancreatitis ‡3 Years Before Cancer Diagnosis df508/S42F M 70 Nonsmoker No No R117H/E528E (splice site) M 75 Smoker Yes No df508/S912L W 56 Smoker No No df508/N1088S W 73 Smoker No No df508/M1191I M 79 Smoker No No df508/S1235R M 73 Smoker No No df508/F1052V M 49 Smoker No No df508/5T M 60 Smoker No No Man indicates man; W, woman. Login to comment

[hide] Cystic fibrosis transmembrane conductance regulato... Am J Respir Crit Care Med. 2010 May 15;181(10):1078-84. Epub 2010 Feb 18. Bienvenu T, Sermet-Gaudelus I, Burgel PR, Hubert D, Crestani B, Bassinet L, Dusser D, Fajac I
Cystic fibrosis transmembrane conductance regulator channel dysfunction in non-cystic fibrosis bronchiectasis.
Am J Respir Crit Care Med. 2010 May 15;181(10):1078-84. Epub 2010 Feb 18., 2010-05-15 [PMID:20167849]

Abstract [show]
RATIONALE: Although in patients with diffuse bronchiectasis (DB) and a normal sweat test the presence of one mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is frequently observed, its pathogenic role in the development of DB remains unclear. OBJECTIVES: To evaluate the association between CFTR heterozygosity and CFTR protein dysfunction in the airways of patients with DB. METHODS: Nasal potential difference was measured in 122 patients with DB of unknown origin and with a normal sweat test (Cl(-) < 60 mmol/L). They were classified according to the presence of CFTR mutations: zero (85 patients), one (22 patients), or two mutations (15 patients). Control groups comprised 26 healthy subjects, 38 obligate heterozygotes for CFTR, and 92 patients with classic cystic fibrosis (CF) with an abnormal sweat test (Cl(-) > or = 60 mmol/L). Patients classified as mild-CF were carrying at least one mild mutation and patients classified as severe-CF were homozygous for the F508del mutation. MEASUREMENTS AND MAIN RESULTS: There was a continuum of airway CFTR dysfunction in the study population as shown by nasal potential difference measurements, ranging from normal values in healthy subjects, to intermediate values in subjects with DB, to highly abnormal values in subjects classified as severe-CF. This continuum of airway CFTR dysfunction was thus strongly associated with defects in the CFTR gene. Moreover, among patients with DB, a similar continuum in intermediate nasal potential difference was identified that was associated with the bearing of zero, one, or two CFTR mutations. These electrophysiological phenotypes and CFTR genotypes were also associated with the clinical phenotype, as shown by the frequency of Staphylococcus aureus and Pseudomonas aeruginosa bronchial colonization. CONCLUSIONS: Our study supports the hypothesis that a unique CFTR mutation may have pathogenic consequences in patients with DB.

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82 GENOTYPE AND PHENOTYPE OF PATIENTS WITH DIFFUSE BRONCHIECTASIS BEARING TWO CYSTIC FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR MUTATIONS Patient No. Age (yr) Sex (M/F) CFTR Mutations Sweat Cl2 (mmol/L) Basal PD (mV) NPD Index Age at Onset (yr) FEV1 (% pred) Bacteria Colonization 1 55 F F508del/D1152H 19 219 1.00 54 99 Sa 2 71 F F508del/G576A-R668C 29 223 0.44 70 114 None 3 24 M G542X/3849110kbCT 52 224 1.22 10 78 Pa 4 41 F 394delTT/D1152H 19 225 0.30 41 89 Sa 5 31 M 3849110kbC.T/3849110kbC.T 35 230 0.64 2 30 Sa/Pa 6 74 F G542X/S912L 40 233 0.19 60 106 None 7 50 M W1282X/D1152H 35 236 1.00 10 32 Pa 8 42 F F508del/D1152H 13 240 0.68 30 32 Pa 9 56 F F508del/IVS8-5T 30 242 0.70 10 70 None 10 45 F 394delTT/D1152H 25 242 0.71 18 62 Sa/Pa 11 74 F W1282X/D1152H 25 244 0.66 12 56 Pa 12 23 F S1206X/D1152H 19 244 0.68 13 107 None 13 41 F R553X/R851L-T351S 31 248 0.50 35 72 Pa 14 58 M F508del/R117H-7T 46 251 0.61 45 35 Sa/Pa 15 53 F F508del/R347H 49 258 0.63 40 77 Pa Definition of abbreviations: Cl2 5 chloride; F 5 female; M 5 male; NPD index 5 nasal potential difference index 5 e(response to øCl2 and iso/response to amil); a cut off . Login to comment

[hide] A new complex allele of the CFTR gene partially ex... Genet Med. 2010 Sep;12(9):548-55. Lucarelli M, Narzi L, Pierandrei S, Bruno SM, Stamato A, d'Avanzo M, Strom R, Quattrucci S
A new complex allele of the CFTR gene partially explains the variable phenotype of the L997F mutation.
Genet Med. 2010 Sep;12(9):548-55., [PMID:20706124]

Abstract [show]
PURPOSE: To evaluate the role of complex alleles, with two or more mutations in cis position, of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in the definition of the genotype-phenotype relationship in cystic fibrosis (CF), and to evaluate the functional significance of the highly controversial L997F CFTR mutation. METHODS: We evaluated the diagnosis of CF or CFTR-related disorders in 12 unrelated subjects with highly variable phenotypes. According to a first CFTR mutational analysis, subjects appeared to be compound heterozygotes for a classic mutation and the L997F mutation. A further CFTR mutational analysis was conducted by means of a protocol of extended sequencing, particularly suited to the detection of complex alleles. RESULTS: We detected a new [R117L; L997F] CFTR complex allele in the four subjects with the highest sweat test values and CF. The eight subjects without the complex allele showed the most varied biochemical and clinical outcome and were diagnosed as having mild CF, CFTR-related disorders, or even no disease. CONCLUSIONS: The new complex allele partially explains the variable phenotype in CF subjects with the L997F mutation. CFTR complex alleles are likely to have a role in the definition of the genotype-phenotype relationship in CF. Whenever apparently identical CFTR-mutated genotypes are found in subjects with divergent phenotypes, an extensive mutational search is mandatory.

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103 In vivo findings and, in some cases, in vitro functional characterizations have been reported for [F508C; S1251N],38 [R347H; D979A],39,40 [R74W; D1270N],41 [G628R; S1235R],42,43 [M470V; S1235R],42 [S912L; G1244V],44 [R117H; (TG)mTn],45-47 [R117C; (TG)mTn],46 [S1235R; (TG)mT5],48 [G576A; R668C],10,49 [V562I; A1006E],49 [R352W; P750L],49 [1198_1203del TGGGCT; 1204GϾA],49 [V754M; CFTRdele3_10,14b_16],50 and [F508del; I1027T].51 These complex alleles have been found in patients with either CF or CFTR-RD, although more often in the former. Login to comment
105 Both in vivo and in vitro studies have also highlighted cases in which there is one main mutation with the phenotypical effect that is worsened by a second mutation, which may even be a neutral variant when isolated, as occurs for F508C,38 R74W,41 S912L,44 and M470V.42 However, different effects have also been described, as in the case of the two M470 and R1235 variants, which give rise to a hyperactive CFTR when present on different alleles but have a suppressive effect when combined on the same allele.42 In addition, the finding of complex alleles in CFTR-RD seems to suggest that a second CFTR mutation may even lead to a partial reversion of the phenotype.43 Indeed, in a reduced number of complex alleles, the effect of the second mutation may partially correct the functional defect, thereby lessening the phenotypical effect, as has been demonstrated for the R553Q mutation in the [F508del; R553Q] complex allele by in vivo52 and in vitro53 studies and for the R553M mutation in the [F508del; R553M] complex allele by an in vitro study.53 A milder phenotypical effect has also been demonstrated for the [R334W; R1158X]54 and [-102T; S549R(TϾG)]55 complex alleles if compared with alleles carrying, respectively, isolated R1158X or S549R(TϾG). Login to comment

[hide] A neutral variant involved in a complex CFTR allel... Hum Genet. 2005 May;116(6):454-60. Epub 2005 Mar 3. Clain J, Lehmann-Che J, Girodon E, Lipecka J, Edelman A, Goossens M, Fanen P
A neutral variant involved in a complex CFTR allele contributes to a severe cystic fibrosis phenotype.
Hum Genet. 2005 May;116(6):454-60. Epub 2005 Mar 3., [PMID:15744523]

Abstract [show]
In order to further elucidate the contribution of complex alleles to the wide phenotypic variability of cystic fibrosis (CF), we investigated the structure-function relationships of a severe CF-associated complex allele [p.S912L;p.G1244V]. To evaluate the contribution of each mutation to the phenotype, cystic fibrosis transmembrane conductance regulator (CFTR) mutants were expressed in HeLa cells and analysed for protein processing and Cl- channel activity. Both p.G1244V and [p.S912L;p.G1244V] mutants had normal protein processing but markedly decreased Cl- channel activity compared with wild-type. Notably, the double mutant displayed a dramatic decrease in Cl- channel activity compared with p.G1244V (P<0.001). p.S912L had normal protein processing and no detectable impact on CFTR function. In other respects, the p.S912L variation was identified in compound heterozygosity with p.R709X in a healthy fertile man. Together, these data strongly support the view that p.S912L in isolation should be considered as a neutral variant but one that might significantly impair CFTR function when inherited in cis with another CFTR mutation. Our data also further document the contribution of complex alleles to the wide phenotypic variability of CF. The results of functional studies of such complex alleles in other genetic diseases are discussed.

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0 ORIGINAL INVESTIGATION Je´ roˆ me Clain Æ Jacqueline Lehmann-Che Emmanuelle Girodon Æ Joanna Lipecka Aleksander Edelman Æ Michel Goossens Pascale Fanen A neutral variant involved in a complex CFTR allele contributes to a severe cystic fibrosis phenotype Received: 1 September 2004 / Accepted: 12 December 2004 / Published online: 3 March 2005 Ó Springer-Verlag 2005 Abstract In order to further elucidate the contribution of complex alleles to the wide phenotypic variability of cystic fibrosis (CF), we investigated the structure-function relationships of a severe CF-associated complex allele [p.S912L;p.G1244V]. Login to comment
2 Both p.G1244V and [p.S912L;p.G1244V] mutants had normal protein processing but markedly decreased ClÀ channel activity compared with wild-type. Login to comment
4 p.S912L had normal protein processing and no detectable impact on CFTR function. Login to comment
5 In other respects, the p.S912L variation was identified in compound heterozygosity with p.R709X in a healthy fertile man. Login to comment
6 Together, these data strongly support the view that p.S912L in isolation should be considered as a neutral variant but one that might significantly impair CFTR function when inherited in cis with another CFTR mutation. Login to comment
14 The [p.S912L;p.G1244V] double-mutant allele is associated with severe CF (Savov et al. 1995). Login to comment
16 In vitro experiments and identification of a healthy fertile man bearing the [p.R709X]+[p.S912L] genotype both indicate that the p.S912L mutation should be considered to be a polymorphism. Login to comment
17 Surprisingly, the combination of p.S912L and p.G1244V decreases J. Clain Æ J. Lehmann-Che Æ E. Girodon M. Goossens Æ P. Fanen (&) Service de Biochimie et Ge´ ne´ tique, Hoˆ pital Henri Mondor, Institut National de la Sante´ et de la Recherche Me´ dicale U.468, AP-HP, 94010 Cre´ teil, France E-mail: pascale.fanen@im3.inserm.fr Tel.: +33-1-49812854 Fax: +33-1-48993345 J. Lipecka Æ A. Edelman Faculte´ de Me´ decine Necker, Institut National de la Sante´ et de la Reche0rche Me´ dicale U.467, 156 Rue de Vaugirard, 75015 Paris, France Hum Genet (2005) 116: 454-460 DOI 10.1007/s00439-004-1246-z cAMP-dependent ClÀ channel activity compared with p.G1244V, highlighting the deleterious effect exerted by polymorphisms on the phenotype when combined in cis with a mutation. Login to comment
54 The diagnosis of CF was confirmed in the fetus by the presence of two allelic mutations, 711+1G fi T, a splice mutation of intron 5 inherited from the mother, and p.R709X, a nonsense mutation of exon 13 inherited from the father; the father carried the p.S912L variant (not transmitted to the fetus) on the other chromosome. Login to comment
56 Results Processing of CFTR mutants To analyse the processing and ClÀ channel activity of p.S912L, p.G1244V and [p.S912L;p.G1244V] mutant proteins, wild-type and mutant CFTR alleles were expressed in HeLa cells. Login to comment
63 The kinetics of core-glycosylated and mature forms of mutant CFTRs were nearly identical to those of the wild-type, indicating that p.S912L, p.G1244V and [p.S912L;p.G1244V] mutations did not affect maturation of the CFTR protein. Login to comment
75 p.S912L- transfected cells displayed a similar proportion of responsive cells to wild-type cells (92% of responsive cells vs 83%; P>0.2; Fig.3), suggesting that ClÀ channel function was not affected by this mutation. Login to comment
76 Unlike p.S912L, the p.G1244V and [p.S912L; p.G1244V] CFTR transfected cells showed a marked decrease in cAMP-stimulated ClÀ conductance compared with wild-type (43% and 2.4% of responsive cells, respectively vs. Login to comment
79 Surprisingly, whereas the p.S912L mutation had no detectable impact on CFTR function, the [p.S912L;p.G1244V] complex allele showed an almost 20-fold reduction in cAMP-dependent conductive pathway compared with the p.G1244V deleterious mutant (2.4% of responsive cells vs. Login to comment
81 Discussion Clinical data suggest that the combination of p.S912L and p.G1244V mutations in cis ([p.S912L;p.G1244V] complex allele) produces a severe CF phenotype similar to that of p.F508del homozygotes. Login to comment
83 Thus, the poor ClÀ channel activity measured in vitro (2.4% of the wild-type) and the severity of the associated disease observed in vivo (pancreatic insufficiency, severe lung disease and elevated sweat electrolytes) both indicate that the [p.S912L;p.G1244V] complex allele should be considered to be a severe allele. Login to comment
85 In this study, we have Fig. 2 a-d Pulse-chase experiments showing the turnover of the immature and mature forms of wild-type and the mutant CFTR proteins (representative of two independent experiments) Table 1 Summary of MEQ fluorescence assay results from mock-transfected, wild-type and mutant cells Statistic DFstim-DFbasal Mock Wild-type p.S912L p.G1244V [p.S912L;p.G1244V] n 28 64 36 53 42 Mean 0.002 0.023 0.036 0.005 0.001 SEM 0.001 0.017 0.028 0.005 0.001 Range 0-0.005 0-0.340 0-0.140 0-0.034 0-0.006 provided functional and clinical evidence that the p.S912L mutation is not a disease-causing mutation on the basis of the following data. Login to comment
86 (1) In vitro experiments have shown that the p.S912L mutation has no detectable impact on CFTR processing and ClÀ channel function. Login to comment
89 Notably, the healthy father of a CF fetus carrying the p.S912L mutation has been identified in our laboratory in the framework of prenatal diagnosis, whereas the CF-associated p.R709X mutation (Bonizzato et al. 1995) has been detected on his other allele. Login to comment
91 Together, these data strongly support the view that the p.S912L mutation should be considered to be a neutral variant. Login to comment
96 Surprisingly, the p.G1244V and [p.S912L;p.G1244V] alleles affect in vitro ClÀ channel function in different ways. Login to comment
97 This might indicate that p.S912L and p.G1244V mutations occurring on the same allele cause severe structural alterations worsening the effect of the p.G1244V mutation on CFTR function. Login to comment
98 However, we cannot exclude the possibility that the p.S912L mutation may have a slight, but undetectable, effect on CFTR function and that a threshold is reached when these two mutations are combined in cis. Login to comment
99 An important consequence of our observation is that when a patient or an asymptomatic relative carries the p.S912L mutation, the p.G1244V mutation should be sought in order to exclude a CF allele; this is important for genetic counselling. Login to comment
100 These results have important implications for CF because they suggest that ''neutral`` missense mutations, such as p.S912L, might significantly alter CFTR function when inherited in cis with another mutation. Login to comment

[hide] Membrane-integration characteristics of two ABC tr... J Mol Biol. 2009 Apr 17;387(5):1153-64. Epub 2009 Feb 21. Enquist K, Fransson M, Boekel C, Bengtsson I, Geiger K, Lang L, Pettersson A, Johansson S, von Heijne G, Nilsson I
Membrane-integration characteristics of two ABC transporters, CFTR and P-glycoprotein.
J Mol Biol. 2009 Apr 17;387(5):1153-64. Epub 2009 Feb 21., [PMID:19236881]

Abstract [show]
To what extent do corresponding transmembrane helices in related integral membrane proteins have different membrane-insertion characteristics? Here, we compare, side-by-side, the membrane insertion characteristics of the 12 transmembrane helices in the adenosine triphosphate-binding cassette (ABC) transporters, P-glycoprotein (P-gp) and the cystic fibrosis transmembrane conductance regulator (CFTR). Our results show that 10 of the 12 CFTR transmembrane segments can insert independently into the ER membrane. In contrast, only three of the P-gp transmembrane segments are independently stable in the membrane, while the majority depend on the presence of neighboring loops and/or transmembrane segments for efficient insertion. Membrane-insertion characteristics can thus vary widely between related proteins.

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113 For CFTR, we chose mutations located in TM1CFTR (F87L, G91R), TM3CFTR (P205S, L206W), TM4CFTR (C225R), TM5CFTR (DF311, G314E), TM6CFTR (R334L/W, I336K/R/D, I340N/S, L346P, R347L/H), TM8CFTR (S909I, S912L), TM9CFTR (I1005R, A1006E), TM10CFTR (Y1032N), and TM12CFTR (M1137R, ΔM1140, M1140K), or close to the TM region of TM1CFTR (R74W, L102R/P), TMF2CFTR (R117P/L, L137P), and TM11CFTR (M1101K/R). Login to comment
109 For CFTR, we chose mutations located in TM1CFTR (F87L, G91R), TM3CFTR (P205S, L206W), TM4CFTR (C225R), TM5CFTR (DF311, G314E), TM6CFTR (R334L/W, I336K/R/D, I340N/S, L346P, R347L/H), TM8CFTR (S909I, S912L), TM9CFTR (I1005R, A1006E), TM10CFTR (Y1032N), and TM12CFTR (M1137R, ƊM1140, M1140K), or close to the TM region of TM1CFTR (R74W, L102R/P), TMF2CFTR (R117P/L, L137P), and TM11CFTR (M1101K/R). Login to comment

[hide] CFTR mutation combinations producing frequent comp... Hum Mutat. 2012 Nov;33(11):1557-65. doi: 10.1002/humu.22129. Epub 2012 Jul 2. El-Seedy A, Girodon E, Norez C, Pajaud J, Pasquet MC, de Becdelievre A, Bienvenu T, des Georges M, Cabet F, Lalau G, Bieth E, Blayau M, Becq F, Kitzis A, Fanen P, Ladeveze V
CFTR mutation combinations producing frequent complex alleles with different clinical and functional outcomes.
Hum Mutat. 2012 Nov;33(11):1557-65. doi: 10.1002/humu.22129. Epub 2012 Jul 2., [PMID:22678879]

Abstract [show]
Genotype-phenotype correlations in cystic fibrosis (CF) may be difficult to establish because of phenotype variability, which is associated with certain CF transmembrane conductance regulator (CFTR) gene mutations and the existence of complex alleles. To elucidate the clinical significance of complex alleles involving p.Gly149Arg, p.Asp443Tyr, p.Gly576Ala, and p.Arg668Cys, we performed a collaborative genotype-phenotype correlation study, collected epidemiological data, and investigated structure-function relationships for single and natural complex mutants, p.[Gly576Ala;Arg668Cys], p.[Gly149Arg;Gly576Ala;Arg668Cys], and p.[Asp443Tyr;Gly576Ala;Arg668Cys]. Among 153 patients carrying at least one of these mutations, only three had classical CF and all carried p.Gly149Arg in the triple mutant. Sixty-four had isolated infertility and seven were healthy individuals with a severe mutation in trans, but none had p.Gly149Arg. Functional studies performed on all single and natural complex mutants showed that (1) p.Gly149Arg results in a severe misprocessing defect; (2) p.Asp443Tyr moderately alters CFTR maturation; and (3) p.Gly576Ala, a known splicing mutant, and p.Arg668Cys mildly alter CFTR chloride conductance. Overall, the results consistently show the contribution of p.Gly149Arg to the CF phenotype, and suggest that p.[Arg668Cys], p.[Gly576Ala;Arg668Cys], and p.[Asp443Tyr;Gly576Ala;Arg668Cys] are associated with CFTR-related disorders. The present study emphasizes the importance of comprehensive genotype-phenotype and functional studies in elucidating the impact of mutations on clinical phenotype. Hum Mutat 33:1557-1565, 2012. (c) 2012 Wiley Periodicals, Inc.

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107 of patients Main diagnosis Additional information Age at diagnosis Sweat test (Cl-,mmol/L) Allele 1 Allele 2 1 FBA Fetal death 20 wg NA p.[Gly576Ala;Arg668Cys] p.Ser1235Arg 1 FBA Unknown outcome p.Arg668Cys p.Phe508del 1 FBA Not CF at birth 38 wg NA p.[Asp443Tyr;Gly576Ala;Arg668Cys] NI 1 FBA Not CF at birth 28 wg NA p.[Gly576Ala;Arg668Cys] NI 1 Healthy CF patient`s mother NA NA p.[Asp443Tyr;Gly576Ala;Arg668Cys] p.Phe508del 1 Healthy Newborn, elevated IRT but normal ST (not CF) Birth <30 p.[Gly576Ala;Arg668Cys] p.Phe508del 1 Healthy Mother of a CF fetus (p.[Phe508del]+ [phe508del]) NA NA p.[Gly576Ala;Arg668Cys] p.Phe508del 1 Healthy Mother of a fetus with FBA but not affected with CF NA NA p.[Gly576Ala;Arg668Cys] p.Phe508del 2 Healthy Mother of a fetus with FBA but not affected with CF NA NA p.[Gly576Ala;Arg668Cys] NI 1 Healthy CF patient`s mother 59 y NA p.[Gly576Ala;Arg668Cys] p.Phe508del 1 Healthy CF patient`s mother NA NA p.[Gly576Ala;Arg668Cys] p.[Ser912Leu;Asn1303Lys] 1 Healthy CF patient`s mother 32 y NA p.[Gly576Ala;Arg668Cys] p.Leu137Arg 1 Healthy CF carrier`s partner NA NA p.[Gly576Ala;Arg668Cys] c. Login to comment

[hide] Double mutant alleles: are they rare? Hum Mol Genet. 1995 Jul;4(7):1169-71. Savov A, Angelicheva D, Balassopoulou A, Jordanova A, Noussia-Arvanitakis S, Kalaydjieva L
Double mutant alleles: are they rare?
Hum Mol Genet. 1995 Jul;4(7):1169-71., [PMID:8528204]

Abstract [show]
The presence of two different mutations carried by the same CF allele has been demonstrated in four out of 44 Bulgarian CF patients during a systematic search of the entire coding sequence of the CFTR gene. Two of the double mutant alleles include one nonsense and one missense mutation and although the nonsense mutation can be considered to be the main defect, the amino acid substitutions are good candidates for disease-causing mutations as well. One double mutant carries two missense mutations whose contribution to the CF phenotype is difficult to evaluate. The findings suggest that double mutant alleles may be more common than expected and could account for some of the problems in phenotype-genotype correlations. Such alleles may have important implications for molecular diagnosis and genetic counselling.

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44 S912L and G1244V A C->T transition at nucleotide position 2867 in exon 15 and a G->T transversion at position 3863 in exon 20 of the CFTR gene were found in a patient who also carries G542X. Login to comment
45 The first missense mutation results in the substitution of leucine for serine (S912L) in the transmembrane region of the CFTR protein (TM8), whereas the second leads to the replacement of glycine by valine (G1244V) in the second nucleotide binding domain. Login to comment
55 The other double mutant CF allele detected in this study carries two missense mutations (S912L + G1244V) whose independent contribution to the clinical phenotype is difficult to evaluate. Login to comment
59 It is also possible that G1244V alone would result in mild CF and that S912L is the main defect in the double mutant S912L + G1244V allele. Login to comment
67 Neither S912L nor G1244V have been found to occur in isolation in any of our patients. Login to comment

[hide] Cystic fibrosis: genotypic and phenotypic variatio... Annu Rev Genet. 1995;29:777-807. Zielenski J, Tsui LC
Cystic fibrosis: genotypic and phenotypic variations.
Annu Rev Genet. 1995;29:777-807., [PMID:8825494]

Abstract [show]
Cystic fibrosis (CF) is a common genetic disorder in the Caucasian population. The gene was identified in 1989 on the basis of its map location on chromosome 7. The encoded gene product, named cystic fibrosis transmembrane conductance regulator (CFTR), corresponds to a cAMP-regulated chloride channel found almost exclusively in the secretory epithelial cells. Although the major mutation that results in a single amino acid deletion (F508) accounts for 70% of the disease alleles, more than 550 additional mutant alleles of different forms have been detected. Many of these mutations can be divided into five general classes in terms of their demonstrated or presumed molecular consequences. In addition, a good correlation has been found between CFTR genotype and one of the clinical variables--pancreatic function status. An unexpected finding, however, is the documentation of CFTR mutations in patients with atypical CF disease presentations, including congenital absence of vas deferens and several pulmonary diseases. Thus, the implication of CFTR mutation is more profound than CF alone.

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593 Not surprisingly, Rl17H is associated with CF only when the allele also contains Table 2 Examples of complex alleles in the CfTR gene Principal Second site mutationa Location alteration Location Reference R75X exon 3 125G --.. C promoter 57 405 + IG --.. A intron 3 3030G --.. A exon 15 57 R1l7H exon 4 129G --.. C promoter 203 RI17H exon 4 IVS8 : 5T or 7T intron 8 101 R297Q exon 7 IVS8 : 5T or 7T intron 8 60 aF508 exon 10 R553Q exon II 59 aF508 exon 10 1I027T exon I7a 57 8F508 exon 10 deletion of D7S8 500 kb 3' of 186 CfTR S549N exon II R75Q exon 3 205a L619S exon 13 1716G � A exon 10 57 G628R (G � C) exon 13 SI235R exon 19 47 2184insA exon 13 IVS:5T exon 9 J Zielenski, J Bal, 0 Markiewicz, L-C Tsui, unpublished data A800G exon 13 IVS8 : 5T or 7T intran 8 31 S912L exon 15 GI244V exon 20 149 GlO69R exon 17b L88X exon 3 149 3732deiA exon 19 Kl200E exon 19 70 3849 + IOkbC � intron 19 R668C exon 13 57 T SI251N exon 20 F508C exon 10 94 The status of principal mutation may not be clear in every case; e.g. G628R(G --> C) vs S1235R. Login to comment

[hide] CFTR mutations spectrum and the efficiency of mole... PLoS One. 2014 Feb 26;9(2):e89094. doi: 10.1371/journal.pone.0089094. eCollection 2014. Zietkiewicz E, Rutkiewicz E, Pogorzelski A, Klimek B, Voelkel K, Witt M
CFTR mutations spectrum and the efficiency of molecular diagnostics in Polish cystic fibrosis patients.
PLoS One. 2014 Feb 26;9(2):e89094. doi: 10.1371/journal.pone.0089094. eCollection 2014., [PMID:24586523]

Abstract [show]
Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane regulator gene (CFTR). In light of the strong allelic heterogeneity and regional specificity of the mutation spectrum, the strategy of molecular diagnostics and counseling in CF requires genetic tests to reflect the frequency profile characteristic for a given population. The goal of the study was to provide an updated comprehensive estimation of the distribution of CFTR mutations in Polish CF patients and to assess the effectiveness of INNOLiPA_CFTR tests in Polish population. The analyzed cohort consisted of 738 patients with the clinically confirmed CF diagnosis, prescreened for molecular defects using INNOLiPA_CFTR panels from Innogenetics. A combined efficiency of INNOLiPA CFTR_19 and CFTR_17_TnUpdate tests was 75.5%; both mutations were detected in 68.2%, and one mutation in 14.8% of the affected individuals. The group composed of all the patients with only one or with no mutation detected (109 and 126 individuals, respectively) was analyzed further using a mutation screening approach, i.e. SSCP/HD (single strand conformational polymorphism/heteroduplex) analysis of PCR products followed by sequencing of the coding sequence. As a result, 53 more mutations were found in 97 patients. The overall efficiency of the CF allele detection was 82.5% (7.0% increase compared to INNOLiPA tests alone). The distribution of the most frequent mutations in Poland was assessed. Most of the mutations repetitively found in Polish patients had been previously described in other European populations. The most frequent mutated allele, F508del, represented 54.5% of Polish CF chromosomes. Another eight mutations had frequencies over 1%, 24 had frequencies between 1 and 0.1%; c.2052-2053insA and c.3468+2_3468+3insT were the most frequent non-INNOLiPA mutations. Mutation distribution described herein is also relevant to the Polish diaspora. Our study also demonstrates that the reported efficiency of mutation detection strongly depends on the diagnostic experience of referring health centers.

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57 Finally, S912L (SVM +2.12), found in a single chromosome with F508del in trans, has been reported in the CFMDB as pathogenic only if in cis with c.3067-3072del6; since the latter was not found in the analyzed patient, we considered S912L a neutral polymorphism. Login to comment
101 The more recent estimates provide much lower values, ranging from 1:5000 [14], 1:6000 cited in WHO 2002 report [15] to 1:7500 for Southeastern Poland estimated for a 1-year period of Table 2. Cont. Exon / intron (legacy) Exon / intron (Ensembl) Protein change SVM value cDNA (HGVS nomenclature) gDNA (cDNA +132 bp) Number of PL CF chromosomes Reference a Mutations in trans 15 17 L967S 0.27 c.2900T.C 3032T.C 1 CFMDB; rs1800110 unknown 18 21 D1152H 0.50 c.3454G.C 3586G.C 1 CFMDB; rs75541969 F508del Sequence changes considered as lacking pathogenic effect 4 4 I148T 2.04 c.443T.U 575T.U 4 IL19e unknown 13 14 I752V 0.35 c.2254A.G 2386A.G 1 Novelf F508 15 17 S912L 2.12 c.2735C.T 2867C.T 1 CFMDBg ; rs121909034 F508 Legend: a IL19 i 17 - mutations included in the INNOLiPA tests (see below); CFMDB - non-INNOLiPA mutations present in the CTFR mutation database; novel - mutations first reported in this study; b in three chromosomes R668C with G576A in trans; c F508del, c.1585-1G.A, G542X, N1303K or c.579+3A.G; d F508del, G542X, R553X or N1303K; e not pathogenic if not in cis with c.3067-72del6 (l.n.3199del6); f not pathogenic - see explanation the text; g not pathogenic if not in cis with G1244V. Login to comment

[hide] A Genotypic-Oriented View of CFTR Genetics Highlig... Mol Med. 2015 Apr 21;21:257-75. doi: 10.2119/molmed.2014.00229. Lucarelli M, Bruno SM, Pierandrei S, Ferraguti G, Stamato A, Narzi F, Amato A, Cimino G, Bertasi S, Quattrucci S, Strom R
A Genotypic-Oriented View of CFTR Genetics Highlights Specific Mutational Patterns Underlying Clinical Macrocategories of Cystic Fibrosis.
Mol Med. 2015 Apr 21;21:257-75. doi: 10.2119/molmed.2014.00229., [PMID:25910067]

Abstract [show]
Cystic fibrosis (CF) is a monogenic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The genotype-phenotype relationship in this disease is still unclear, and diagnostic, prognostic and therapeutic challenges persist. We enrolled 610 patients with different forms of CF and studied them from a clinical, biochemical, microbiological and genetic point of view. Overall, there were 125 different mutated alleles (11 with novel mutations and 10 with complex mutations) and 225 genotypes. A strong correlation between mutational patterns at the genotypic level and phenotypic macrocategories emerged. This specificity appears to largely depend on rare and individual mutations, as well as on the varying prevalence of common alleles in different clinical macrocategories. However, 19 genotypes appeared to underlie different clinical forms of the disease. The dissection of the pathway from the CFTR mutated genotype to the clinical phenotype allowed to identify at least two components of the variability usually found in the genotype-phenotype relationship. One component seems to depend on the genetic variation of CFTR, the other component on the cumulative effect of variations in other genes and cellular pathways independent from CFTR. The experimental dissection of the overall biological CFTR pathway appears to be a powerful approach for a better comprehension of the genotype-phenotype relationship. However, a change from an allele-oriented to a genotypic-oriented view of CFTR genetics is mandatory, as well as a better assessment of sources of variability within the CFTR pathway.

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54 [1117-8A>G;1727G>C; 2002C>T]) and mutations G1069R (p.Gly1069Arg), D614G (p.Asp614Gly), S42F (p.Ser42Phe) and S912L (p.Ser912Leu) should also be considered as part of this extension, even if not found in CF-PI but studied up to the DEL step because they are found in genotypes with an unknown allele. Login to comment
385 [Gly576Ala;Arg668Cys] D579G c.1736A>G CF-PS varying clinical consequence p.Asp579Gly E585X c.1753G>T CF-PI CF-causing p.Glu585* H609L c.1826A>T CFTR-RD nd p.His609Leu A613T c.1837G>A CF-PS nd p.Ala613Thr D614G c.1841A>G CF-PS unknown significance p.Asp614Gly 2143delT c.2012delT CF-PS CF-causing p.Leu671* 2183AA>G c.2051_2052delAAinsG CF-PI,CF-PS CF-causing p.Lys684SerfsX38 2184insA c.2052_2053insA CF-PI CF-causing p.Gln685ThrfsX4 R709X c.2125C>T CF-PI CF-causing p.Arg709* L732X c.2195T>G CF-PI CF-causing p.Leu732* R764X c.2290C>T CF-PI CF-causing p.Arg764* Q779X c.2335C>T uncertain: CF-PI and/or CF-PS nd p.Gln779* E831X c.2491G>T CF-PS CF-causing p.Glu831* Y849X c.2547C>A CF-PI CF-causing p.Tyr849* ex14b-17bdel c.2620-674_3367+198del9858 CF-PI nd 2789+5G>A c.2657+5G>A CF-PI,CF-PS CF-causing 2790-2A>G c.2658-2A>G CF-PS nd S912L c.2735C>T uncertain: found only with an unknown allele in trans nd p.Ser912Leu S945L c.2834C>T CF-PS CF-causing p.Ser945Leu S977F c.2930C>T CFTR-RD varying clinical consequence p.Ser977Phe L997F c.2991G>C CF-PS,CFTR-RD,CBAVD non CF-causing p.Leu997Phe ex17a-18del c.2988+1173_3468+2111del8600 CF-PI nd P1013L c.3038C>T CFTR-RD nd p.Pro1013Leu Y1032C c.3095A>G CFTR-RD nd p.Tyr1032Cys 3272-26A>G c.3140-26A>G CF-PS CF-causing L1065P c.3194T>C CF-PI,CF-PS CF-causing p.Leu1065Pro L1065R c.3194T>G uncertain: CF-PI and/or CF-PS nd p.Leu1065Arg R1066C c.3196C>T CF-PI CF-causing p.Arg1066Cys R1066H c.3197G>A CF-PI CF-causing p.Arg1066His G1069R c.3205G>A uncertain: found only with an unknown allele in trans varying clinical consequence p.Gly1069Arg Continued on next page of 0.021). Login to comment