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

The study investigated the highly polymorphic HumFGA short tandem repeat in a sample of 219 unrelated and native individuals from Bologna, and analysed a complete database of FGA allele frequency distributions in 57 world-wide populations collected from the literature.

The HumFGA polymorphism was screened by automated fluorescence analysis of PCR-amplified labelled sample fragments performed with an ABI PRISM 310 Genetic Analyser. Genetic distances (Dsw, delta mu2 and Fst) between populations were computed with the MSAT.2 program. Non-metric multidimensional scaling (nmMDS) and neighbour-joining trees (NJTs) were used to investigate patterns of population affinities. Correspondence analysis of the genetic relationships among populations was also performed.

The FGA microsatellite locus is a population marker with a high degree of polymorphism throughout the world. Fourteen HumFGA alleles, ranging in size from 18 to 29 repeats, were identified and sequenced in the Bologna population. The sample was in Hardy-Weinberg equilibrium and had a heterozygosity value of 0.86. Results obtained from the multivariate analyses were consistent in showing great similarity among Europeans. The few African populations investigated were characterized by an even higher level of polymorphism, probably related to the ancient peopling of that continent.