Gross genomic rearrangements involving deletions in the CFTR gene: characterization of six new events from a large cohort of hitherto unidentified cystic fibrosis chromosomes and meta-analysis of the underlying mechanisms.
Gross genomic rearrangements involving deletions in the CFTR gene have recently been found to account for approximately 20% of unidentified cystic fibrosis (CF) chromosomes in both French and Italian patients. Using QMPSF and walking quantitative DHPLC, six novel mutations (three simple deletions, two complex deletions with short insertions of 3-6 bp, and a complex deletion with a 182 bp inverted downstream sequence) were characterized by screening 274 unidentified CF chromosomes from 10 different countries. These lesions increase the total number of fully characterized large CFTR genomic rearrangements involving deletions to 21. Systematic analysis of the 42 associated breakpoints indicated that all 21 events were caused by nonhomologous recombination. Whole gene complexity analysis revealed a significant correlation between regions of low sequence complexity and the locations of the deletion breakpoints. Known recombination-promoting motifs were noted in the vicinity of the breakpoints. A total of 11 simple deletions were potentially explicable in terms of the classical model of replication slippage. However, the complex deletions appear to have arisen via multiple mechanisms; three of the five complex deletions with short insertions and both examples of large inverted insertions (299 and 182 bp, respectively) can be explained by either a model of serial replication slippage in cis (SRScis) or SRS in trans (SRStrans). Finally, the nature and distribution of large genomic rearrangements in the CFTR gene were compared and contrasted with those of two other genes, DMD and MSH2, with a view to gaining a broader understanding of DNA sequence context in mediating the diverse underlying mutational mechanisms.
INSERM, U613 (Génétique Moléculaire et Génétique Epidémiologique), Brest, France. claude.ferec@univ-brest.fr
Claude
C
Férec
Teresa
T
Casals
Nadia
N
Chuzhanova
Milan
M
Macek
Thierry
T
Bienvenu
Andrea
A
Holubova
Caitriona
C
King
Trudi
T
McDevitt
Carlo
C
Castellani
Philip M
PM
Farrell
Molly
M
Sheridan
Sarah-Jane
SJ
Pantaleo
Ourida
O
Loumi
Taieb
T
Messaoud
Harry
H
Cuppens
Francesca
F
Torricelli
Garry R
GR
Cutting
Robert
R
Williamson
Maria Jesus Alonso
MJ
Ramos
Pier Franco
PF
Pignatti
Odile
O
Raguénès
David N
DN
Cooper
Marie-Pierre
MP
Audrézet
Jian-Min
JM
Chen
D001483:Base Sequence; D019295:Computational Biology; D003550:Cystic Fibrosis / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004252:DNA Mutational Analysis; D017353:Gene Deletion; D016678:Genome; D006801:Humans; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D011995:Recombination, Genetic
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator