The intermediate population frequency of the unfavorable T allele of the insulin secretion-disrupting gene TCF7L2 (rs7903146) in Kazakhs (15.2%), compared to European and Asian populations, indicates that these genetic loci are not universally applicable genetic markers for a predisposition to T2D and should be replicated in each specific ethnic population. The gene discussed is TCF7L2; the disease is type 2 diabetes mellitus.