Abstract: 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.
Abstract: This study evaluated the prevalence of overweight and obesity in the male Sardinian population (Italy), and verifies that it has increased over the last 30 years. Data were collected during 2003-2004 from military registers in the Archive of the Military District of Cagliari for the years 1969 and 1998. A total of 22,345 forms were analysed from all Sardinia. The conscripts were classified on the basis of their place of residence and socioeconomic status. The overall prevalence of overweight and obesity in Sardinia were 4.33% and 0.55%, respectively, for the conscripts of 1969 and 9.8% and 3% for 1998. Olbia-Tempio (northern Sardinia) was the province with the highest incidence of overweight and obesity in 1969, and Nuoro (central Sardinia) had the highest incidence in 1998. Distribution of body mass index, overweight and obesity across the island showed a statistically significant heterogeneity that strongly decreased from 1969 to 1998. Among the conscripts of 1969, the incidence of overweight and obesity were higher in rural than in urban regions. An opposite trend was observed for the 1998 prevalence, it being more frequent in urban than rural regions. Comparison with other Italian regions was made. The percentages of overweight and obese individuals in Sardinia have markedly increased during the last 30 years, but their low incidence with respect to other Italian populations could be explained by the genetic peculiarity of the island. The change in the internal distribution of obesity clearly reflects socioeconomic changes.
Abstract: Detection of genes that have been targeted by natural selection is a powerful tool for predicting regions of the genome potentially linked with diseases and of interest in the field of genetic epidemiology. In recent years, several methods to detect patterns of natural selection have been developed. In general, these tests are based on different assumptions and parameters; hence, the detection of outlier loci with more than one statistical approach simultaneously will support the candidate status of a particular locus. In this study, we evaluated the presence of patterns of positive selection in 17 short tandem repeat loci genotyped in six different human populations from the Mediterranean area, for a total of 429 individuals. To identify patterns of selective pressure, we applied three different neutrality tests on the basis of different models, performing pairwise comparisons between populations. Results show the presence of one marker, a (CA)n repeat located in exon 29 of the NOS1 gene, which seems significant in the three different tests in two pairwise comparisons: Sicily vs Morocco and Balearic Islands vs Morocco. This suggests that this locus and its genome localization are candidates for further studies to investigate selective pressure, as well as for association studies.
Abstract: More than 2700 unrelated individuals from Europe, northern Africa and western Asia were analyzed for the marker M269, which defines the Y chromosome haplogroup R1b1b2. A total of 593 subjects belonging to this haplogroup were identified and further analyzed for two SNPs, U106 and U152, which define haplogroups R1b1b2g and R1b1b2h, respectively. These haplogroups showed quite different frequency distribution patterns within Europe, with frequency peaks in northern Europe (R1b1b2g) and northern Italy/France (R1b1b2h).
Abstract: In this work we investigated about the presence of a correlation between a (CA)n repeat located in exon 29 of NOS1 gene and the beta-thalassemia trait in Corsica Island (France). We genotyped a sample of individuals with beta-thalassemia minor (N=110) and an ethnically matched control (N=113) from Balagna, a region of Corsica Island (France). Results highlighted the high frequencies of allele with 16 and 17 repeats in the thalassemic sample. From these results we suggest, that high frequencies of alleles with 16 and 17 repeats, could be a consequence of past malarial endemicity.
Abstract: The ACTN3 (R577X) gene encodes for a structural protein that is exclusively expressed in the Z-disc of type II muscle fibers. Homozygosis (577XX) for the stop codon in the ACTN3 polymorphism results in alpha-actinin-3 complete deficiency. Previous studies have shown low frequencies of the ACTN3 XX genotype in elite sprinters compared to the general population. This study tests 35 Italian elite gymnasts and 53 controls. ACTN3 XX genotype (2.8% vs. 18.8%; p < 0.04) and X allele (27.1% vs. 43.3%; p < 0.04) frequencies were significantly lower in gymnasts compared to controls. The ACTN3 XX genotype was underrepresented in female and male gymnasts compared to controls, but was only significant for males (male: 0% vs. 16.1%, p < 0.04; female: 5.5% vs. 22.7%, p = 0.39). These results suggest that alpha-actinin-3 is beneficial to skeletal muscle function in generating forceful contractions at high velocity. In conclusion, our results associated the ACTN3 R577X polymorphism with male and possibly female elite gymnastic performance.
Abstract: Using 10 Y-chromosome short tandem repeat allelic and haplotypic frequencies, we examined genetic variation within the population of Corsica and its relationship with other Mediterranean populations. The most significant finding is the high level of genetic differentiation within Corsica, with strong evidence of an effective barrier to male-mediated gene flow between the south and the rest of the island. This internal differentiation most probably results from low exogamy among small isolated populations and also from the orography of the island, with a central mountain chain running the length of the island restricting human movement. This physical barrier is reflected not only in present-day intraisland linguistic and genetic differences but also in the relatedness of Corsican regions to other Mediterranean groups. Northwest and Central Corsica are much closer to West Mediterranean populations, whereas South Corsica is closer to Central-North Sardinia and East Mediterranean populations.
Abstract: The 17 Y-chromosomal short tandem repeats (STRs) included in the AmpFlSTR YFiler Amplification Kit (AB Applied Biosystems) (DYS19, DYS3891, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635 and GATA H4.1) were typed in 100 samples from North Sardinia (Italy). A total of 91 different haplotypes were found, where 9 haplotypes were shared by two individuals. The overall haplotype diversity (HD) was 0.9982. DYS458 non-consensus alleles were found in one samples, and one in the DYS438. We found a double peak in one sample for the DYS19 with alleles 15/16. Population comparisons with available 10 YSTR loci data in Mediterranean Basin samples were undertaken, significant differences were observed between our sample and all the compared populations, except for a entire sample from Sardinia. Prediction of haplogroups showed I2al was found to be the most frequent haplogroup (33%) in our sample. Testing high-resolution Y-chromosome data sets it is useful in autochthonous population and micro-population studies to highlight the most informative loci for evolutionary aims.
Abstract: The present work attempts to determine the distribution of CYP11A (TTTTA)n genotype and allele frequencies in 10 European and North African populations. This polymorphism has been associated with hyperandrogenism by several association studies. To our knowledge, this is the first study investigating the ethnic variation of this polymorphism. DNA was extracted from 868 whole-blood samples with the standard phenol-chloroform technique, and PCR reactions were carried out using fluorescent primers as described previously. PCR products were analyzed by an ABI 3,730 DNA Analyzer. A total of six alleles were identified, ranging from 220 bp (4 repeats [4R]) to 250 bp (10R). The most frequent allelic fragment size in all populations was 4R, with frequencies ranging from 47.9% (Sicily) to 62.8% (Tuscany and Germany). Allelic frequencies showed high heterogeneity between analyzed populations. We detected a significant gradient for alleles 4R and 8R. In this study, we report the allele frequency distribution of CYP11A (TTTTA)n showing a north-south geographic gradient. This result could be useful for epidemiological studies about hyperandrogenism.
Abstract: Genetic isolates with a history of a small founder population, long-lasting isolation and population bottlenecks represent exceptional resources in the identification of disease genes. In these populations the disease allele reveals Linkage Disequilibrium (LD) with markers over significant genetic intervals, therefore facilitating disease locus identification. In a previous study we examined the LD extension on the Xq13 region in three Corsican sub-populations from the inner mountainous region of the island. On the basis of those previous results we have proposed a multistep procedure to carry out studies aimed at the identification of genes involved in complex diseases in Corsica. A prerequisite to carry out the proposed multi-step procedure was the presence of different degrees of LD on the island and a common genetic derivation of the different Corsican sub-populations. In order to evaluate the existence of these conditions in the present paper we extended the analysis to the Corsican coastal populations.
