ABCMdb

PMID: 20717170

Rene C, Paulet D, Girodon E, Costa C, Lalau G, Leclerc J, Cabet-Bey F, Bienvenu T, Blayau M, Iron A, Mittre H, Feldmann D, Guittard C, Claustres M, Georges M
p.Ser1235Arg should no longer be considered as a cystic fibrosis mutation: results from a large collaborative study.
Eur J Hum Genet. 2011 Jan;19(1):36-42. Epub 2010 Aug 18., [PubMed]

Sentences

No. Mutations Sentence Comment

0 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ARTICLE p.Ser1235Arg should no longer be considered as a cystic fibrosis mutation: results from a large collaborative study Ce´line Rene´*,1,2,3, Damien Paulet1,2, Emmanuelle Girodon4, Catherine Costa4, Guy Lalau5, Julie Leclerc5, Faı¨za Cabet-Bey6, Thierry Bienvenu7, Martine Blayau8, Albert Iron9, Herve´ Mittre10, Delphine Feldmann11, Caroline Guittard3, Mireille Claustres1,2,3 and Marie des Georges3 Among the 1700 mutations reported in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, a missense mutation, p.Ser1235Arg, is a relatively frequent finding. Login to comment 1 ABCC7 p.Ser1235Arg To clarify its clinical significance, we collected data from 104 subjects heterozygous for the mutation p.Ser1235Arg from the French CF network, addressed for various indications including classical CF, atypical phenotypes or carrier screening in subjects with or without a family history. Login to comment 3 ABCC7 p.Ser1235Arg An exhaustive CFTR gene analysis identified a second mutation in cis of p.Ser1235Arg in all CF patients and in 81.8% CBAVD patients. Login to comment 4 ABCC7 p.Ser1235Arg Moreover, epidemiological data from 42100 individuals found a higher frequency of p.Ser1235Arg in the general population than in CF or CBAVD patients. Login to comment 5 ABCC7 p.Ser1235Arg These data, added to the fact that in silico analysis and functional assays suggest a benign nature of this substitution, give several lines of evidence against an association of p.Ser1235Arg with CF or CBAVD. Login to comment 11 ABCC7 p.Ser1235Arg ABCC7 p.Gly628Arg However, a clear statement on the pathogenicity of a mutation is difficult to obtain, in particular for missense mutations.2,3 Moreover, the existence of at least two mutations or sequence variations on the same allele, named complex alleles, complicates genetic counseling.4-11 p.Ser1235Arg (3837T4G or c.3705T4G), initially reported by Cuppens et al.12 with a second mutation on the same allele, p.Gly628Arg, is located in a poorly conserved region in the second nucleotide binding fold (NBF2). Login to comment 12 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg Earlier reports failed to establish a clear impact of p.Ser1235Arg on the phenotype severity.13-16 The aim of this study was to determine whether we should consider p.Ser1235Arg as a possible CF-associated mutation or reclassify it as a neutral polymorphism. Login to comment 13 ABCC7 p.Ser1235Arg Thus, we implemented a large collaborative study to repertory the patients or individuals bearing the p.Ser1235Arg mutation from nine French laboratories and compared their phenotype, genotype and associated CFTR haplotypes. Login to comment 15 ABCC7 p.Ser1235Arg Here, we gather lines of evidence that p.Ser1235Arg should be no longer considered as a CF mutation. Login to comment 16 ABCC7 p.Ser1235Arg MATERIALS AND METHODS Patients and individuals Data were collected from 104 subjects heterozygous or compound heterozygous for the p.Ser1235Arg mutation registered from the French CF network of Received 22 March 2010; revised 10 June 2010; accepted 29 June 2010; published online 18 August 2010 1Universite´ Montpellier1, UFR de Me´decine, Montpellier, France; 2INSERM U827, Laboratoire de Ge´ne´tique de Maladies Rares, Montpellier, France; 3CHU Montpellier, Hoˆpital Arnaud de Villeneuve, Laboratoire de Ge´ne´tique Mole´culaire, Montpellier, France; 4Service de Biochimie-Ge´ne´tique et Inserm U955 e´quipe 11, Groupe Henri Mondor-Albert Chenevier, APHP, Cre´teil, France; 5Poˆle de Biochimie et Biologie Mole´culaire, Centre de Biologie Pathologie, CHU de Lille, Lille, France; 6Service d`Endocrinologie Mole´culaire et Maladies rares, Centre de Biologie et Pathologie Est, CHU de Lyon, Bron, France; 7Laboratoire de Biochimie-Ge´ne´tique, Hoˆpital Cochin, APHP, Paris, France; 8Laboratoire de Ge´ne´tique Mole´culaire, CHU Pontchaillou, Rennes, France; 9Laboratoire de Ge´ne´tique Mole´culaire, Service de Ge´ne´tique Me´dicale, Groupe Hospitalier Pellegrin, CHU de Bordeaux, Bordeaux, France; 10Laboratoire de Biochimie B, CHU Georges Cle´menceau, Caen, France; 11Laboratoire de Biochimie et Biologie Mole´culaire, Hoˆpital d`Enfants Armand Trousseau, APHP, Paris, France *Correspondence: Dr C Rene´, INSERM U827, Laboratoire de Ge´ne´tique Mole´culaire et Chromosomique, CHU, Institut Universitaire de Recherche Clinique, 641 Avenue du Doyen Gaston Giraud, Montpellier Cedex 5, 34093, France. Login to comment 21 ABCC7 p.Ser1235Arg Molecular epidemiological study To evaluate the p.Ser1235Arg frequency in the general population, we screened for 2114 samples: 929 anonymized dried-blood spot of neonates presenting positive or negative immunoreactive trypsinogen (IRT) at day 3 obtained from the center for neonatal screening in Montpellier, South of France, and 1185 genomic DNA from CF patient`s or relative`s partners from the cohort of the Southern France (Laboratory of Molecular Genetics of Montpellier) or from the cohort of the Northern France (Laboratory of Molecular Genetics of Lille). Login to comment 28 ABCC7 p.Ser1235Arg If p.Ser1235Arg was found alone, a screening for large CFTR rearrangements was performed using a semiquantitative fluorescent multiplex PCR assay. Login to comment 31 ABCC7 p.Ser1235Arg To determine the haplotype associated with the p.Ser1235Arg allele, six microsatellite markers (IVS1(CA), IVS8(CA), IVS8(TG)m, IVS8(T)n, IVS17b(TA) and IVS17b(CA)) and one biallelic marker (p.Met470Val or 1540A4G (c.1408A4G)) were investigated. Login to comment 33 ABCC7 p.Ser1235Arg Spots of 3 mm diameter, punched from anonymized cards, were distributed in 96-well plates and DNA was extracted using methanol extraction.17 p.Ser1235Arg was screened using DHPLC technology and each abnormal pattern was confirmed by sequencing analysis. Login to comment 34 ABCC7 p.Ser1235Arg Computer-assisted analysis To predict the potential pathogenicity of p.Ser1235Arg, we used PolyPhen and SIFT softwares. Login to comment 41 ABCC7 p.Ser1235Arg To gain some insight into the potential effect of the p.Ser1235Arg mutation from a structural point of view, we used the experimental structures of MJ0796 (in complex with ATP, pdb identifier 1l2t) as template for modeling as previously described by Eudes et al.22 The MJ0796 structure was visualized with MBT SimpleViewer software (San Diego, CA, USA). Login to comment 45 ABCC7 p.Ser1235Arg The p.Ser1235Arg mutation was inserted into the pcDNA3-CFTR vector by site-directed mutagenesis using QuickChange II site-directed mutagenesis kit (Agilent Technologies, Massy, France) according to the manufacturer`s instructions. Login to comment 46 ABCC7 p.Ser1235Arg The human CFTR genomic region encompassing exon 19 with the flanking intronic sequences was amplified from a patient heterozygous for the p.Ser1235Arg using primers: FOR 5'-AATTCTGGAGCTCGAGCAGGCCTATA CAGAGCCCATT-3' and REV 5'-CTCTTAATTTGCTAGCCATTTTCAAG ATGGGAAATCTAAAACA-3' (which introduce NheI and XhoI sites in the PCR product). Login to comment 65 ABCC7 p.Ser1235Arg RESULTS Genotype/phenotype description of individuals carrying p.Ser1235Arg Among 104 subjects from 91 unrelated families reported by the 9 French laboratories, 6 patients are affected with classical CF (Table 1a). Login to comment 68 ABCC7 p.Ser1235Arg The (TG)13(T)5 allele was found in nine subjects with p.Ser1235Arg (Table 1a). Login to comment 69 ABCC7 p.Arg117His ABCC7 p.Arg1070Trp Of these, eight were compound heterozygous for p.Phe508del, and two for mutations associated with CF-related diseases,3,27 (p.Arg117His;T7) and p.Arg1070Trp (http://www.genet.sickkids.on.ca/cftr/). Login to comment 70 ABCC7 p.Ser1235Arg Among 42 patients with monosymptomatic disease carrying p.Ser1235Arg (Table 1a), eight cases (19%) were compound heterozygotes, seven for a severe mutation and one for the intronic variant 406-6T4C (c.274-6T4C). Login to comment 71 ABCC7 p.Ser1235Arg Of these, five harbored the (TG)13(T)5 allele associated in cis with p.Ser1235Arg. Login to comment 72 ABCC7 p.Ser1235Arg In all, 34 individuals (81%) were heterozygous for p.Ser1235Arg: 5 with reduced sperm quality; 16 with sinopulmonary problems such as bronchiectasis, asthma, nasal polyposis and chronic obstructive pulmonary disease; and 13 with digestive symptoms (meconium ileus at birth, pancreatitis and liver disease). Login to comment 75 ABCC7 p.Ser1235Arg Among them, five carried only p.Ser1235Arg and were considered simple heterozygote because extensive scanning did not reveal a second CF mutation.28 Three cases were compound heterozygous for another mutation. Login to comment 78 ABCC7 p.Val920Met The second carried the rare missense mutation p.Val920Met and depressed values of digestive enzymes were observed at 17 weeks of pregnancy. Login to comment 79 ABCC7 p.Arg668Cys ABCC7 p.Gly576Ala In the last case, the fetus carried the complex allele (p.Gly576Ala; p.Arg668Cys), considered as a mild mutation involved in CBAVD or disseminated bronchiectasis phenotypes in adults.29-31 Although the fetus presented hyperechogenic fetal bowel, the parents were reassured regarding the risk of classical CF. Login to comment 81 ABCC7 p.Ser1235Arg Among 37 individuals tested for cascade carrier screening, 14 were compound heterozygous for p.Ser1235Arg and another CFTR mutation (Table 1b), all being relatives of patients or carriers. Login to comment 84 ABCC7 p.Ser1235Arg Notably, cases 4 and 5 were two fertile fathers carrying a class I mutation (severe) associated in trans of p.Ser1235Arg. Login to comment 85 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg Frequencies of p.Ser1235Arg in the general, CF and CBAVD French populations In 2114 subjects of the general population, 32 p.Ser1235Arg alleles were detected, representing an allelic frequency of 0.76% (Table 2). Login to comment 87 ABCC7 p.Ser1235Arg This allele frequency was compared with those of patients collated in a French study affected with CF (8/7420 alleles) or CBAVD (7/1626 alleles), 0.11 and 0.43%, respectively.32 By w2 statistical analysis, the p.Ser1235Arg allelic frequency is significantly higher in the general population than in CF patients (0.76 vs 0.11%, Po0.001) but not statistically different from the CBAVD group (0.76 vs 0.43%, P4 0.1). Login to comment 89 ABCC7 p.Ser1235Arg Among them, five with severe disease, harbored the p.Arg785X mutation, whereas another presenting a mild phenotype had the complex allele (p.Ser1235Arg;T5). Login to comment 90 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg When the p.Ser1235Arg frequencies in CF, CBAVD and the general population were compared with the frequencies of p.Phe508del (Table 2), it appears that p.Ser1235Arg is as frequent as p.Phe508del (P¼0.91) in the general population (respectively, 0.76 vs 0.82%); however, its implication in classical CF is significantly different (0.11 vs 67.2% (Po0.0001) and 2.86% (Po0.0001), respectively). Login to comment 91 ABCC7 p.Ser1235Arg p.Ser1235Arg haplotype backgrounds Haplotypic markers and familial segregation were completed in 36 cases (Table 3). Login to comment 92 ABCC7 p.Ser1235Arg The analysis of haplotypes based on four intragenic CFTR markers (IVS1(CA), IVS8(CA), M470V and IVS17b(CA)) revealed that p.Ser1235Arg is always present on the same haplotype 26-17-M-13. Login to comment 94 ABCC7 p.Ser1235Arg Table 1a Genotype and phenotype of CF, CBAVD and CF-like patients carrying the p.Ser1235Arg mutation Genotype Phenotype No. Login to comment 95 ABCC7 p.Gly551Asp ABCC7 p.Arg117His ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Arg668Cys ABCC7 p.Arg1070Trp ABCC7 p.Val920Met of subjects Allele 1 Allele 2 p.Ser1235Arg;p.Arg785X p.Phe508del Severe CF 2 p.Ser1235Arg;p.Arg785X NAa Severe CF 1 p.Ser1235Arg;875+1G4A (c.743+1C4A) 3629delT (c.3497delT) Severe CF 1 p.Ser1235Arg;p.Arg785X p.Gly542X Severe CF 1 p.Ser1235Arg;(TG)13(T)5 p.Gly551Asp Mild CF 1 p.Ser1235Arg;(TG)13(T)5 p.Phe508del CBAVD 6 p.Ser1235Arg;(TG)13(T)5 p.Arg1070Trp CBAVD 1 p.Ser1235Arg;(TG)13(T)5 p.Arg117His; (T)7 CBAVD 1 p.Ser1235Arg p.Phe508del CBAVD 1 p.Ser1235Arg - CBAVD 1 p.Ser1235Arg;(TG)13(T)5 p.Phe508del CUAVD 1 Suspicion CF/mild phenotype: p.Ser1235Arg - Genital symptoms 5 p.Ser1235Arg - Respiratory symptoms 16 p.Ser1235Arg;(TG)13(T)5 p.Phe508del Respiratory symptoms 2 p.Ser1235Arg 406-6T4C (c.274-6T4C) Respiratory symptoms 1 p.Ser1235Arg p.Tyr1092X Respiratory symptoms 1 p.Ser1235Arg p.Glu831X Respiratory symptoms 1 p.Ser1235Arg p.Gln493X Respiratory symptoms 1 p.Ser1235Arg p.Ile507del Respiratory symptoms 1 p.Ser1235Arg - Digestive symptoms 13 p.Ser1235Arg p.Gly542X Digestive symptoms 1 p.Ser1235Arg - Hyperechogenic fetal bowel 5 p.Ser1235Arg p.Arg668Cys; p.Arg576Ala Hyperechogenic fetal bowel 1 p.Ser1235Arg p.Val920Met Hyperechogenic fetal bowel 1 p.Ser1235Arg p.Phe508del Hyperechogenic fetal bowel 1 aNA: not available; we could only test the mother and a healthy sister (the patient was deceased and the father`s DNA was not available). Login to comment 97 ABCC7 p.Ser1235Arg The p.Arg785X found in CF patients in cis of the p.Ser1235Arg occurs on a single haplotype 26-17-12-7-M-35-13. Login to comment 98 ABCC7 p.Ser1235Arg The complex allele (p.Ser1235Arg;(TG)13(T)5) characteristic of CBAVD was also found to be carried on a unique haplotype (26-17-13-5-M-33-13). Login to comment 104 ABCC7 p.Ser1235Arg To evaluate the functional impact of the mutation on the CFTR maturation, we performed western blot analysis on whole-cell extracts from COS-7 cells transfected with either wild-type or the p.Ser1235Arg constructs (Figure 1c). Login to comment 105 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg The results show the presence of the fully glycosylated CFTR protein (band C) with the p.Ser1235Arg construct, suggesting that the maturation of the p.Ser1235Arg-CFTR protein is not altered. Login to comment 106 ABCC7 p.Ser1235Arg These results suggest that p.Ser1235Arg has no functional impact on the CFTR protein. Login to comment 107 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg Functional impact of the p.Ser1235Arg on the splicing According to the Splicing Sequences Finder tools,34 p.Ser1235Arg does not seem to impact the splicing of CFTR transcript. Login to comment 111 ABCC7 p.Ser1235Arg As shown in Figure 2b, compared with the wild type, the presence of the p.Ser1235Arg alteration does not modify the exon 19 inclusion in the mRNA. Login to comment 112 ABCC7 p.Ser1235Arg Together, these data suggest that p.Ser1235Arg has no effect on the CFTR mRNA splicing. Login to comment 113 ABCC7 p.Ser1235Arg DISCUSSION Since its initial description in 1993, the clinical significance of the p.Ser1235Arg mutation remains unclear. Login to comment 114 ABCC7 p.Ser1235Arg This ignorance makes genetic Table 1b Genotype and familial history of asymptomatic individuals carrying the p.Ser1235Arg mutation Case no. Login to comment 115 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Arg1070Trp Genotype Familial information Allele 1 Allele 2 1 p.Ser1235Arg; (TG)13(T)5 p.Phe508del Brother of CUAVD (no parental project) 2 p.Ser1235Arg; (TG)13(T)5 p.Phe508del Sister of CUAVD 3 p.Ser1235Arg; (TG)13(T)5 p.Arg1070Trp Sister of CBAVD 4 p.Ser1235Arg p.Gly542X Father of CF [p.Phe508del]+ [p.Gly542X] and healthy children [p.Ser1235Arg]+[(TG)11(T)5] 5 p.Ser1235Arg p.Gln493X Father of CF [p.Phe508del]+ [p.Gln493X] 6 p.Ser1235Arg p.Phe508del Uncle of CF (no parental project) 7 p.Ser1235Arg p.Phe508del Mother of CF [p.Phe508del]+ [1717-1G4A (c.1585-1G4A)] 8 p.Ser1235Arg 2347delG (c.2215delG) Mother of CF [p.Phe508del]+ [2347delG (c.2215delG)] 9 p.Ser1235Arg (TG)11(T)5 Mother of non-CF fetus with hyperechogenic fetal bowel [p.Phe508del]+[(TG)11(T)5] 10 p.Ser1235Arg p.Phe508del Sister of CBAVD 11 p.Ser1235Arg p.Phe508del Sister of CBAVD 12 p.Ser1235Arg p.Glu831X Sister of CF-like patient 13 p.Ser1235Arg p.Phe508del First-cousin of CF-like patient 14 p.Ser1235Arg p.Phe508del A 18-month-old child with prenatal diagnostic based on familial history of CF Table 2 Comparison of the allelic frequencies of p.Ser1235Arg and p.Phe508del in the general population, CF and CBAVD patients Populations Significance (P-values) General population, this study CF patients30 (n¼7420) CBAVD patients30 (n¼1626) General population vs CF General population vs CBAVD p.Phe508del 0.82% (n¼1950) 67.2% 21.6% S (Po0.05) S (Po0.05) p.Ser1235Arg 0.76% (n¼4228) 0.11% 0.43% S (Po0.05) NS (P¼0.17) Significance (P-values) p.Phe508del vs p.Ser1235Arg NS (P¼0.91) S (Po0.05) S (Po0.05) Abbreviations: N, number of unrelated tested chromosomes; S, significant difference; NS, no significant difference. Login to comment 117 ABCC7 p.Ser1235Arg Table 3 CFTR haplotypes for 36 fully haplotyped p.Ser1235Arg chromosomes from CF, CBAVD patients, ruled-out CF (including CF-like symptoms and fetal echogenic bowel) and general population IVS1(CA)-IVS8(CA)- M470V-IVS17b(CA) IVS8(TG)m- IVS8(T)n Mutation in cis IVS17b(TA) n % 26-17-M-13 12-7 p.Arg785X 35 4 11.1 875+1G4A (c.743+1C4A) 36 1 2.8 None 33 1 2.8 35 5 13.8 36 9 25 37 4 11.1 38 1 2.8 40 1 2.8 44 1 2.8 7 1 2.8 13-5 33 8 22.2 counseling very difficult, especially in the context of prenatal diagnosis. Login to comment 118 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg Through genotype/phenotype analysis of patients or individuals carrying p.Ser1235Arg, analyzed by the French network and functional analysis, we present several lines of evidence that argue against an association of p.Ser1235Arg with CF or CBAVD, although a partial penetrance of p.Ser1235Arg could not be ruled out. Login to comment 119 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg First, the presence of a complex allele [p.Ser1235Arg;class I mutation] in trans of a severe mutation in five patients presenting severe disease (Table 1a) strongly suggests that p.Ser1235Arg alone cannot be considered as a CF-causing mutation. Login to comment 120 ABCC7 p.Ser1235Arg Moreover, among the 11 patients referred for CAVD, 9 are compound heterozygous for a mutation and the complex allele [p.Ser1235Arg;(TG)13(T)5]. Login to comment 121 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg The (TG)13(T)5 allele without the contribution of p.Ser1235Arg is sufficient to result in male infertility or in mild phenotypes.24,25,35 Among the two patients with p.Ser1235Arg as single allele, one has the mutation p.Phe508del in trans whereas no other mutation was identified in the second one. Login to comment 124 ABCC7 p.Ser1235Arg Three, carrying the complex allele [p.Ser1235Arg;(TG)13(T)5] are sisters or brother of CBAVD or CUAVD patients and no respiratory or digestive symptom was reported. Login to comment 126 ABCC7 p.Ser1235Arg Three adult males are compound heterozygous for p.Ser1235Arg and a severe mutation; two (cases 4 and 5) are biological fathers of CF children and transmitted the severe mutation. Login to comment 129 ABCC7 p.Ser1235Arg Third, the frequency of the p.Ser1235Arg in the general population (Table 2) is higher than in CF and CBAVD patients, in accordance with previous reports,14,37 and is close to the p.Phe508del frequency (0.82%). Login to comment 130 ABCC7 p.Ser1235Arg In contrast, in CF or CBAVD groups, the p.Ser1235Arg frequency is significantly lower than p.Phe508del. Login to comment 133 ABCC7 p.Ser1235Arg These data are confirmed by functional studies, which showed that p.Ser1235Arg does not alter the CFTR mRNA correct splicing and the protein maturation. Login to comment 134 ABCC7 p.Ser1235Arg ABCC7 p.Gly628Arg These data are consistent with previous functional study of this locus in combination with alleles found at p.Met470Val and p.Gly628Arg loci.13 Wei et al.13 demonstrated that the p.Ser1235Arg CFTR protein does not cause change in the chloride transport activity. Login to comment 135 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg ABCC7 p.Gly628Arg Besides, the p.Gly628Arg/p.Ser1235Arg mutant protein induces a significantly lower cAMP-dependent chloride transport activity than the Figure 1 Structural and processing impact of p.Ser1235Arg mutation on the CFTR protein. Login to comment 140 ABCC7 p.Ser1235Arg (c) COS-7 cell lines were transfected with either wild-type or p.Ser1235Arg CFTR constructs. Login to comment 144 ABCC7 p.Gly628Arg p.Gly628Arg mutant protein, showing the major importance of genetic background, particularly for missense mutations. Login to comment 145 ABCC7 p.Ser1235Arg In a second step, we determined the haplotypes linked to p.Ser1235Arg and found the same haplotype in 72.4% of cases. Only the IVS17b(TA) marker presents a large variability, although three haplotypes, deriving one from the other by addition or deletion of one dinucleotide (35, 36 or 37 repeats), represent 455% of the alleles. Login to comment 146 ABCC7 p.Ser1235Arg Besides, IVS1(CA) 26, a rare allele in the European populations (4.2 vs 80% for alleles 22, 23 and 24),38 is strictly linked to p.Ser1235Arg. Login to comment 147 ABCC7 p.Ser1235Arg In CBAVD patients, the haplotype 26-17-13-5-M-33-13 was found in 85.7% of p.Ser1235Arg alleles. Login to comment 148 ABCC7 p.Ser1235Arg These data suggest the further change of the (TG)12(T)7 to (TG)13(T)5 on a chromosome bearing the alteration p.Ser1235Arg on a background IVS17b(TA)33. Login to comment 149 ABCC7 p.Ser1235Arg ABCC7 p.Ser1235Arg Together, these data suggest that p.Ser1235Arg could derive from a founding event and haplotypes differing by a single microsatellite could depend on slippage phenomena, as already proposed.39 In conclusion, there are now strong lines of evidence against a severe deleterious effect of p.Ser1235Arg and its association with classical CF or CBAVD disease. Login to comment 151 ABCC7 p.Ser1235Arg These data highlight the importance of searching for a complex allele whenever p.Ser1235Arg is identified. Login to comment 152 ABCC7 p.Ser1235Arg The absence of clinical effects in healthy individuals who are compound heterozygous for the p.Ser1235Arg and another severe mutation is helpful to provide adequate genetic counseling to the families with regard to its transmission in offspring. Login to comment 169 ABCC7 p.Ile148Thr 8 Rohlfs EM, Zhou Z, Sugarman EA et al: The I148T CFTR allele occurs on multiple haplotypes: a complex allele is associated with cystic fibrosis. Login to comment 175 ABCC7 p.Asp1270Asn ABCC7 p.Arg74Trp ABCC7 p.Ile148Thr 11 Claustres M, Altieri JP, Guittard C, Templin C, Chevalier-Porst F, Des Georges M: Are p.I148T, p.R74W and p.D1270N cystic fibrosis causing mutations? Login to comment 181 ABCC7 p.Ser1235Arg 14 Monaghan KG, Feldman GL, Barbarotto GM, Manji S, Desai TK, Snow K: Frequency and clinical significance of the S1235R mutation in the cystic fibrosis transmembrane conductance regulator gene: results from a collaborative study. Login to comment 212 ABCC7 p.Ser1235Arg (b) RT-PCR analysis of mRNA of cell expressing wild-type42 or p.Ser1235Arg(S1235R) constructs. Login to comment 213 ABCC7 p.Ser1235Arg BeaS2B cells were transfected with either empty, wild-type or p.Ser1235Arg pSPL3 vector. Login to comment