FNDC5/Irisin polymorphisms are associated with osteopenia in postmenopausal Mayan-Mestizo women.

OBJECTIVE: This study aimed to analyze the association between rs3480 and rs16835198 of FNDC5/Irisin and their haplotypes with variations in bone mineral density (BMD) and osteopenia/osteoporosis in postmenopausal Mayan-Mestizo women. METHODS: We studied 547 postmenopausal women of Maya-Mestizo origin. BMD was measured in the lumbar spine and total hip by dual-energy X-ray absorptiometry. DNA was obtained from blood leukocytes. rs3480 and rs16835198 of FNDC5/Irisin were studied using real-time PCR allelic discrimination. Differences between the means of BMD according to genotype were analyzed with covariance. Allele frequency differences were assessed by χ2 and logistic regression was used to test for associations. Pairwise linkage disequilibrium between polymorphisms was calculated by direct correlation r2, and haplotype analysis was conducted. RESULTS: Under a recessive model, we observed a significant association of rs3480 with the presence of osteopenia at the total hip and femoral neck (p = 0.008 and p = 0.003, respectively). For rs16835198, we found an association with osteopenia at the total hip and femoral neck in a dominant model (p = 0.043 and p = 0.009, respectively). CONCLUSIONS: We found an association of rs3480 with risk to present osteopenia at the total hip and femoral neck, while rs16835198 was associated as a protector for presence of osteopenia only at the femoral neck.

Origin and genetic differentiation of three Native Mexican groups (Purépechas, Triquis and Mayas): contribution of CODIS-STRs to the history of human populations of Mesoamerica.

BACKGROUND: CODIS-STRs in Native Mexican groups have rarely been analysed for human identification and anthropological purposes. AIM: To analyse the genetic relationships and population structure among three Native Mexican groups from Mesoamerica. SUBJECTS AND METHODS: 531 unrelated Native individuals from Mexico were PCR-typed for 15 and 9 autosomal STRs (Identifiler™ and Profiler™ kits, respectively), including five population samples: Purépechas (Mountain, Valley and Lake), Triquis and Yucatec Mayas. Previously published STR data were included in the analyses. RESULTS: Allele frequencies and statistical parameters of forensic importance were estimated by population. The majority of Native groups were not differentiated pairwise, excepting Triquis and Purépechas, which was attributable to their relative geographic and cultural isolation. Although Mayas, Triquis and Purépechas-Mountain presented the highest number of private alleles, suggesting recurrent gene flow, the elevated differentiation of Triquis indicates a different origin of this gene flow. Interestingly, Huastecos and Mayas were not differentiated, which is in agreement with the archaeological hypothesis that Huastecos represent an ancestral Maya group. Interpopulation variability was greater in Natives than in Mestizos, both significant. CONCLUSION: Although results suggest that European admixture has increased the similarity between Native Mexican groups, the differentiation and inconsistent clustering by language or geography stresses the importance of serial founder effect and/or genetic drift in showing their present genetic relationships.