CFTR mutation combinations producing frequent complex alleles with different clinical and functional outcomes.
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.
Institut de Physiologie et Biologie Cellulaires, Centre National de la Recherche Scientifique Formation de Recherche en Evolution FRE 3511, Université de Poitiers, Poitiers, France.
Ayman
A
El-Seedy
Emmanuelle
E
Girodon
Caroline
C
Norez
Julie
J
Pajaud
Marie-Claude
MC
Pasquet
Alix
A
de Becdelièvre
Thierry
T
Bienvenu
Marie
M
des Georges
Faïza
F
Cabet
Guy
G
Lalau
Eric
E
Bieth
Martine
M
Blayau
Frédéric
F
Becq
Alain
A
Kitzis
Pascale
P
Fanen
Véronique
V
Ladeveze
D000483:Alleles; D019943:Amino Acid Substitution; D003550:Cystic Fibrosis / Q000235:genetics* / Q000503:physiopathology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D005602:France; D005787:Gene Frequency; D056726:Genetic Association Studies; D006367:HeLa Cells; D006579:Heterozygote; D006801:Humans; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D009154:Mutation; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
C505032:CFTR protein, human; D050505:Mutant Proteins; D011994:Recombinant Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator