Vitamin D receptor gene polymorphisms, smoking, and risk of sporadic Parkinson’s disease in Japan

•Polymorphism of FokI may be associated with the risk of Parkinson’s disease.•No relationships were observed between TaqI, ApaI, or BsmI and Parkinson’s disease.•VDR haplotypes inferred were not associated with Parkinson’s disease.•Smoking did not modify the association between FokI and Parkinson’s disease. Epidemiological evidence on the relationships between the vitamin D receptor (VDR) single nucleotide polymorphisms (SNPs) rs731236 (TaqI), rs7975232 (ApaI), rs1544410 (BsmI), and rs2228570 (FokI) and Parkinson’s disease (PD) is inconsistent. We investigated these relationships in 229 sporadic PD patients within six years of onset in Japan. Controls were 357 patients without neurodegenerative disease. Adjustment was made for sex, age, region of residence, and smoking. A significant inverse association was found between SNP rs2228570 and the risk of sporadic PD under the additive but not the co-dominant or dominant model (P=0.048); however, this fell below significance after adjustment for multiple comparisons (adjusted P=0.46). No significant relationships were found between SNPs rs731236, rs7975232, or rs1544410 and the risk of sporadic PD in any genetic model. VDR haplotypes inferred in the current study were not associated with sporadic PD. Compared with subjects with the GA or AA genotype of SNP rs2228570 who had ever smoked, those with the GG genotype who had never smoked had a 3.78-fold increased risk of sporadic PD; however, no significant interaction was observed. VDR SNP rs2228570 may be associated with sporadic PD in Japan. Smoking did not significantly modify the relationship between SNP rs2228570 and sporadic PD.