Selective neutrality analysis of 17 STRs in Mediterranean populations

Estimating population genetics and forensic efficiency of the GlobalFiler PCR amplification kit in the population of Sardinia (Italy)

GlobalFiler is a new PCR amplification kit that includes 21 autosomal short tandem repeats and three sex-determining loci. In the present research, for the first time, the GlobalFiler kit was tested to analyze a sample of 500 unrelated individuals from 18 villages encompassing the entire area of Sardinia (Italy). We tested if the kit, which is a powerful tool in forensic studies, may also find application in the field of population genetics. In agreement with data from the literature on forensic parameters values, marker SE33 showed the highest degree of polymorphism, whereas TPOX was the least informative locus. Seventeen out of twenty-one autosomal markers included in the kit resulted highly polymorphic, and therefore Globalfiler turned out to be highly useful for forensic analysis in the Sardinian population. Moreover, our data suggest developing different STR databases in different populations, like Sardinians, to increase the statistical power of autosomal STR profiling. On the other hand, due to the presence of some very highly polymorphic markers, the efficiency of Globalfiler in detecting geographical variability is affected. Indeed, the differentiation previously observed between the Sardinian and Italian populations appeared greatly reduced and even the presence of genetic isolates, previously recorded when uniparental markers was not revealed.

A gradient of NOS1 overproduction alleles in European and Mediterranean populations

AIM

A (CA)n repeat located in the 3' UTR region of exon 29 of the NOS1 gene (encoding for neuronal nitric oxide synthase) has been shown to affect the size of mRNA. NOS1 mRNA is highly diverse, contributing to changes in transcript generation, degradation, processing, or subcellular targeting. In the present work, we analyzed allele frequencies of this (CA)n repeat in nine populations of the Mediterranean area and Middle Europe. We aimed at testing the presence of a north-south positive gradient of frequencies of ≤17 allele repeats, compatible with the hypothesis of positive selection suggested in two of our previous works, related to the past prevalence of malaria infection in Europe.

RESULTS

Results show significant negative correlations of latitude with frequencies of alleles S and genotypes S/S and S/L (p < 0.01).

CONCLUSIONS

In conclusion, the north-south gradient of S alleles found in the present work would confirm our previous observation about the NOS1 gene, reinforcing the hypothesis of a selective action of malaria infection. This hypothesis is strengthened by the role of nitric oxide in the immunity system.