Influence of Different Evolutive Forces on GDF5 Gene Variability.

The GDF5 gene is involved in the development of skeletal elements, synovial joint formation, tendons, ligaments, and cartilage. Several polymorphisms are present within the gene, and two of them, rs143384 and 143383, were reported to be correlated with osteoarticular disease or muscle flexibility. The aim of this research is to verify if the worldwide distribution of the rs143384 polymorphism among human populations was shaped by selective pressure, or if it was the result of random genetic drift events. Ninety-four individuals of both the male and female sexes, 18-28 years old, from Sardinia were analyzed. We observed the following genotype frequencies: 28.72% of AA homozygotes, 13.83% of GG homozygotes, and 57.45% of AG heterozygotes. The allele frequencies were 0.574 for allele A and 0.426 for allele G. The relationships between the populations were verified via Multidimensional Scaling (MDS). Our data show (i) a clear heterogeneity within the African populations; (ii) a strong differentiation between the African populations and the other populations; and that (iii) the Sardinian population is placed within the European cluster. To reveal possible traces of selective pressure, the Population Branch Statistic (PBS) was calculated; both the rs143384 and 143383 SNPs have low PBS values, suggesting that there are no signals of selective pressure in those areas of the gene.