The HUMFIBRA (FGA) polymorphism in an Italian population and a world-wide frequency distribution analysis

Objective: The study investigated the highly polymorphic HumFGA short tande m repeat in a sample of 219 unrelated and native individuals from Bologna, and analysed a complete database of FGA allele frequency distributions in 5 7 world-wide populations collected from the literature. Methods: The HumFGA polymorphism was screened by automated fluorescence ana lysis of PCR-amplified labelled sample fragments performed with an ABI PRIS M 310 Genetic Analyser. Genetic distances (Dsw, delta mu(2) and Fst) betwee n populations were computed with the MSAT.2 program. Non-metric multidimens ional scaling (nmMDS) and neighbour-joining trees (NJTs) were used to inves tigate patterns of population affinities. Correspondence analysis of the ge netic relationships among populations was also performed. Main results and conclusions: The FGA microsatellite locus is a population marker with a high degree of polymorphism throughout the world. Fourteen Hu mFGA alleles, ranging in size from 18 to 29 repeats, were identified and se quenced in the Bologna population. The sample was in Hardy-Weinberg equilib rium and had a heterozygosity value of 0.86. Results obtained from the mult ivariate analyses were consistent in showing great similarity among Europea ns. The few African populations investigated were characterized by an even higher level of polymorphism, probably related to the ancient peopling of t hat continent.