Absence of cystic fibrosis mutations in a large Asian population sample and occurrence of a homozygous S549N mutation in an inbred Pakistani family.

The occurrence of cystic fibrosis is very rare in the Asian population. Carriers of the mutations most commonly found in Caucasians were not detected in a large Asian population sample of almost 900 chromosomes. However, an affected Pakistani child born to consanguineous parents was further investigated and shown to be homozygous for the mutation S549N (G-->A). Molecular and clinical data are presented which may improve our understanding of the phenotypic effects of the S549N mutation in the CFTR gene.