Introduction: Type 2 diabetes is one of the most common health problems worldwide and its prevalence is rapidly increasing. Although environmental factors play a substantial role in the etiology, genetic susceptibility has been established as an important risk factor. Several recent genome-wide studies and linkage analysis testing have identified and confirmed various T2D susceptibility loci. However, as demonstrated by the results of the HapMap project and by other studies, the allele frequencies of the risk variants differ between populations.
Material and methods: As a preliminary study of the genetic risk evaluation in Portuguese T2D patients, we selected 18 variants that have been consistently associated with T2D (PPARG, KCNJ11, TCF7L2, WFS1, KCNQ1, HNF1B, HHEX, NOTCH2, CDC123, TSPAN8, CDKL1, SLC30A8, CDKN2BAS, ADAMTS9, FTO, IGF2BP2, JAZF1, and THADA) and analyzed 571 DNA samples of a normal Portuguese population. The allele frequencies were calculated and compared with the published frequencies for other European populations.
Results: For all variants, genotype call rates were >99%. All except one variant (TSPAN8 rs7961581) were in HardyWeinberg equilibrium Compared with other studies including normal European Caucasian populations, the allele frequencies of this population were in the same range but still with some differences, more evident for variants in CDKL1, SLC30A8, ADAMTS9, TCFL2, HHEX, HNF1B and WFS1. All these variants are primarily related to β-cell function and affect insulin secretion.
Conclusion: These results indicate that the Portuguese population profile for these variants has its own identity and confirms the relevance of this study as a preliminary step for the evaluation of risk alleles in the Portuguese diabetic patients.