Cystic fibrosis mutations in white and black Americans: an approach to identification of unknown mutations with implications for cystic fibrosis screening.

Abstract

We sought to define the frequency of common cystic fibrosis mutations in white and black American probands from our geographic region. Mutation analysis was performed for delta F508, G551D, G542X, R553X, S549N, an d N1303K. For probands with undetermined mutations single-stranded conformational polymorphism analysis was performed. Among 40 white subjects with cystic fibrosis 26 (65%) were homozygous for delta F508, 10 (25%) were heterozygous for delta F508 and another unknown mutation, and two were homozygous for unknown mutations. Among 10 black probands one was homozygous for delta F508, seven (70%) were heterozygous for delta F508 and another unknown mutation, and one was homozygous for unknown mutations. Single-stranded conformational polymorphism analysis for selected exons was performed for 11 probands with unknown mutations. One mutation was detected in a white proband. Sequencing of this exon showed the mutation to be Q493X. Thirty percent of white subjects and 80% of black subjects carried unknown mutations. In one family single-stranded conformational polymorphism was informative in identifying an undetermined cystic fibrosis mutation.