Are p.I148T, p.R74W and p.D1270N cystic fibrosis causing mutations?
BACKGROUND
To contribute further to the classification of three CFTR amino acid changes (p.I148T, p.R74W and p.D1270N) either as CF or CBAVD-causing mutations or as neutral variations.


METHODS
The CFTR genes from individuals who carried at least one of these changes were extensively scanned by a well established DGGE assay followed by direct sequencing and familial segregation analysis of mutations and polymorphisms.


RESULTS
Four CF patients (out of 1238) originally identified as carrying the p.I148T mutation in trans with a CF mutation had a second mutation (c.3199del6 or a novel mutation c.3395insA) on the p.I148T allele. We demonstrate here that the deletion c.3199del6 can also be associated with CF without p.I148T. Three CBAVD patients originally identified with the complex allele p.R74W-p.D1270N were also carrying p.V201M on this allele, by contrast with non CF or asymptomatic individuals including the mother of a CF child, who were carrying p.R74W-p.D1270N alone.


CONCLUSIONS
These findings question p.I148T or p.R74W-p.D1270N as causing by themselves CF or CBAVD and emphazises the necessity to perform a complete scanning of CFTR genes and to assign the parental alleles when novel missense mutations are identified.
Laboratoire de Génétique Moléculaire, Institut Universitaire de Recherche Clinique et Centre Hospitalier Universitaire, 641 avenue du Doyen Gaston Giraud, 34093 Montpellier, France. Mireille.Claustres@igh.cnrs.fr
Mireille
M
Claustres
Jean-Pierre
JP
Altiéri
Caroline
C
Guittard
Carine
C
Templin
Françoise
F
Chevalier-Porst
Marie
M
Des Georges
D019943:Amino Acid Substitution; D003550:Cystic Fibrosis / Q000235:genetics* / Q000473:pathology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004252:DNA Mutational Analysis; D005192:Family Health; D005260:Female; D005787:Gene Frequency; D006239:Haplotypes; D006801:Humans; D008297:Male; D016254:Mutagenesis, Insertional; D009154:Mutation; D019683:Penetrance; D011110:Polymorphism, Genetic; D017384:Sequence Deletion
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator