CYSTIC-FIBROSIS PATIENTS FROM THE BLACK-SEA REGION - THE 1677DELTA MUTATION

A 2 bp deletion in exon 10 of the CFTR gene, 1677delTA, which is very rare among CF chromosomes worldwide, was found to be a relatively comm on cause of cystic fibrosis in countries located in the region of the Black Sea. The frequency of the mutation was compared among cystic fib rosis patients from several populations, namely Bulgarians, Turks, Gre ek-Cypriots, Georgians, and Russians. The deletion is most common amon g Georgian CF patients and gradually declines in frequency in neighbou ring populations. It is invariably related to a common polymorphic hap lotype which is rare among normal chromosomes in Bulgaria but was foun d to be common in Turkey. The geographic gradient in the frequency of the mutation, along with findings on polymorphic haplotype distributio n, suggest that the mutation is relatively young in evolutionary terms and spread as the result of west and south-bound migrations originati ng from Georgia. The 1677delTA mutation is related to a severe clinica l phenotype with a high early mortality rate among homozygotes and pos sibly to an increased risk of meconium ileus. (C) 1994 Wiley-Liss, Inc .