P034 Polymorphism analysis of 24 short tandem repeats (STRs) in a large sample of Mexican mestizos from Mexico

Aim Patterns of genetic variation within and between populations have provided novel insights into the origin and history of humans. STRs are versatile and informative markers that facilitated a great understanding of the diversity present in natural populations, being a common tool in forensics, paternity and anthropological studies. Data collection for such studies is conducted based on many groups. Mexican Mestizos are of mixed descent and are the result of admixture between the Indigenous people of Asian ancestry inhabiting the country, different Europeans, and to a lesser extent, Africans. We intended to describe the pattern of 24 STRs in Mexican Mestizos for the above purposes. Methods STRs were typed in 817 Mestizo adults, born in Mexico, (55.9% males and 44.1% females), by using PowerPlex21, GenePrint 24 (Promega), Global filer and Identifiler (Thermofisher Scientific) systems. We investigated 24 autosomal STRs in genomic DNAs. The STRs were run in a 3500 Sequencer and the DNA fragment analysis was done with the Gene Mapper ID-X v1.4 software. Allele frequency(AF) was compared with other studies done for forensics. Linkage disequilibrium(Δ), hardy–Weinberg equilibrium (HWE), Power of Exclusion (PE), Power of Discrimination (PD) and R Pearson value were determined. Results A total of 347 alleles at the 24 STR loci were found with corresponding AF ranging between 0.045 and 52.66. These STRs are highly polymorphic being the most diverse FGA, D18551, PentaE, D21511, SE33 and D6S1043 (31–18 alleles). The most frequent alleles >25% were; 10 at D2S441; 11 at D5S818; 11 at D7S820; 14 at D6S1043; 14 at D19S433; 19 & 20 at D12S391; 10 at D7S820. These were compared with data of Central Mexico and from 13 CODIS from Latin American and Caribbeans. Conclusions The 24 autosomal STR loci provide highly informative polymorphic data, since the R Pearson value = 0.985 (SD = 0.02). Some alleles were in Δ, meaning they are not in random association in 13/24 STRs (D16S539, D12S391, D19S433, PentaD, FGA, TH1, TPOX, D18S51, PentaE, D21S11, D18S51, D3S1358, CSF1PO). The PD = up to 0.974, showing high heterozygosity and low probability of finding two individuals with the same genotypes and PE = 0.947 shows the power of detecting variation. STRs may also be used together, since many are in Δ, to solve deficient kinship cases or cases with mutations.