Association of Vitamin D Receptor Genotypes in Sporadic and Familial Parkinsonism

The association of vitamin D with Parkinson's disease (PD) has recently been proposed which acts via vitamin D receptor (VDR). The VDR gene contains a start codon polymorphism that can be detected with the restriction enzyme FokI. Some previous studies reported an association between FokI site and PD and have suggested that this polymorphism alters VDR function. The aim of this study was to identify the association of FokI polymorphism in sporadic and familial form of PD. In present case-control study, blood samples were collected from 60 PD patients in total Isfahan population and 62 unrelated normal individuals from southwest region of Isfahan. Another part of the study had been planned on evaluation of 6 patients with PD and 7 healthy controls from one family with PD pedigree. A PCR-RFLP method used to determine genotypes. Serum levels of 25OHD, parathyroid hormone, calcium, phosphorus and alkaline phosphatase from patients and controls of pedigree were analyzed. In sporadic PD, protection against the development of PD was conferred when F allele exist, but it was not significant (OR = 0.7, 95%CI: 0.44-1.28, P = 0.29). On the other hand, insignificant susceptibility to PD (OR= 1.3, 95%CI: 0.437-1.283, P = 0.39) was correlated to f allele. Obtained results from familial study suggested: the risk ratio of PD in the sample was 4 folds higher for f allele (OR= 4.091, 95%CI: 0.374-44.788, P = 0.22), whereas ff homozygosity for the FokI genotype is a non significant genetic risk factor (2.7 times) for PD compared with other FokI genotypes (OR= 2.667, 95%CI: 0.193-36.756, P = 0.45). ff genotype patients compared with FFpatients showed increased serum level of 25OHD, parathyroid hormone and alkaline phosphatase, but this association was not significant. Our finding focused on FokI RFLP alone, and then we need to analyz other polymorphisms in the VDR gene, such as ApaI, TaqI and BsmI. Because of small population of the study, generalizing these results might be limited.