Comprehensive mutation screening in a cystic fibrosis center.
OBJECTIVE
The identities of a cystic fibrosis (CF) patient's CFTR mutations can influence therapeutic strategies, but because >800 CFTR mutations exist, cost-effective, comprehensive screening requires a multistage approach. Single-strand conformation polymorphism and heteroduplex analysis (SSCP/HA) can be an important part of mutation detection, but must be calibrated within each laboratory. The sensitivity of a combined commercial-SSCP/HA approach to genotyping in a large, ethnically diverse US center CF population has not been established.


METHODS
We screened all 27 CFTR exons in 10 human participants who had an unequivocal CF diagnosis including a positive sweat chloride test and at least 1 unknown allele after commercial testing for the 70 most common mutations by SSCP/HA. These participants were compared with 7 participants who had negative sweat tests but at least 1 other CF-like symptom meriting complete genotyping.


RESULTS
For the 10 CF participants, we detected 11 of 16 unknown alleles (69%) and all 4 of the known alleles (100%), for an overall rate of 75% inpatients not fully genotyped by conventional 70 mutation screen. For 7 participants with negative sweat tests, we confirmed 1 identified mutation in 14 alleles and detected 3 additional mutations. Mutations detected in both groups included 7 missense mutations (S13F, P67L, G98R, S492F, G970D, L1093P, N1303K) and 9 deletion, frameshift, nonsense or splicing mutations (R75X, G542X, DeltaF508, 451-458Delta8 bp, 5T, 663DeltaT, exon 13 frameshift, 1261+1G-->A and 3272-26A-->G). Three of these mutations were novel (G970D, L1093P, and 451-458Delta8 bp(1)). Thirteen other changes were detected, including the novel changes 1812-3 ins T, 4096-278 ins T, 4096-265 ins TG, and 4096-180 T-->G.


CONCLUSIONS
When combined with the 70 mutation Genzyme test, SSCP/HA analysis allows for detection of >95% of the mutations in an ethnically heterogeneous CF center population. We discuss 5 possible explanations that could account for the few remaining undetected mutations.
Wine
J J
JJ
Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, USA.
Kuo
E
E
Hurlock
G
G
Moss
R B
RB
D003550:Cystic Fibrosis / Q000208:ethnology / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004252:DNA Mutational Analysis / Q000379:methods*; D005091:Exons; D005820:Genetic Testing / Q000379:methods; D020180:Heteroduplex Analysis / Q000379:methods; D006801:Humans; D009154:Mutation; D018807:Polymorphism, Single-Stranded Conformational; D012680:Sensitivity and Specificity
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator