In a recent meta-analysis including eight studies (five European, two Asian, and one African), the VDR BsmI or TaqI polymorphisms were found to be significantly associated with AITD risk, including HT and GD (OR 0.801 for B vs. b; OR 0.854 for t vs. T), while the ApaI and FokI polymorphisms were not. The gene discussed is VDR; the disease is hematocrit.