Cystic fibrosis mutations and associated haplotypes in Bulgaria – a comparative population genetic study

Abstract

We present data on the population genetics of cystic fibrosis (CF) in Bulgaria, obtained by comprehensive mutation analysis and the construction of intragenic microsatellite haplotypes. The sample of 262 CF alleles analysed is representative of the patients diagnosed during the period of referral and of the three main ethnic groups in the country. ΔF508 accounted for 100% of Gypsy CF alleles, which thus differed significantly from both Bulgarians and ethnic Turks. In Bulgarian and Turkish CF patients, 92% of the mutant alleles were identified, yielding a total of 25 different mutations, of which only 7 occurred at frequencies higher than 1%. The findings were compared to other European populations and to the distribution of phenylketonuria mutations. Genetic distances and population trees demonstrated that in the south-eastern tip of Europe, the overall distribution of CF mutations and polymorphic haplotypes is very close to that of Mediterranean populations, with a high frequency of N1303K and G542X, a large number of rare mutations and a prevalence of the 23 31 13 haplotype in association with ΔF508. These findings are consistent with a main role for the Neolithic expansion in the shaping of the CF mutation spectrum in Bulgaria and southern Europe.