Whole-exome sequencing in maya indigenous families: variant in PPP1R3A is associated with type 2 diabetes

It has been presumed that increased susceptibility in Mexicans to type 2 diabetes (T2D) is attributed to the Native American genetic ancestry. Nonetheless, it is not known if there are private genetic variants that confer susceptibility to develop T2D in our population. The Maya indigenous group has the highest proportion of Native American ancestry (98%) which makes it a representative group of the original peoples of Mexico. Thus, the aim of the present study is to identify new genetic variants associated with T2D in Maya families. Whole-exome sequencing was performed on DNA samples from Maya families with a third-generation family history of T2D only in one parental line. Four variants were identified for APOB, PPP1R3A, TPPP2, and GPR1 genes, and were further tested for association with T2D in 600 unrelated Maya in a case-control study. For the first time, rs1799999 in PPP1R3A was associated with risk of T2D in Mayan Mexican individuals (OR = 1.625, P = 0.014). Interestingly, carriers of rs1799999 presented increased values of HOMA-IR. In addition, rs1801702 in APOB was associated with total cholesterol and LDL-C (P = 0.019 and P = 0.020, respectively) in normoglycemic individuals; rs3732083 in GPR1 with HOMA-IR (P = 0.016) and rs9624 in TPPP2 with total cholesterol and triglycerides (P = 0.002 and P = 0.005, respectively) in T2D subjects. Overall, these findings support the idea that there are other genetic variants yet to be described, involved in T2D development in Maya population, being insulin resistance and lipid metabolism the main mechanisms implicated. Thus, these results can contribute to the understanding of diabetes genetic background in Mexican population.