Vitamin D Serum Levels and Vitamin D Receptor Genotype in Patients with Parkinson's Disease

Vitamin D is a steroid hormone, known to be involved in the pathogenesis of various neurodegenerative disorders, including Parkinson's disease (PD). We aimed to clarify the relationship between hypovitaminosis D and the predisposition for PD and its clinical presentation. An additional aim was to examine the specific gene polymorphisms associated with vitamin D level.

Total level of 25(OH)-vitamin D (25(OH)D) was measured in the serum of parkinsonian patients (n = 113) and controls (n = 82) using a commercial immunoassay. Genetic analyses were performed using Taqman assays on Real Time PCR amplification system.

Higher frequency of vitamin D deficiency (<50 nmol/L) was observed in PD patients, compared to controls (40.7% and 23.2%, respectively, P = 0.010). It was also a positive predictive marker of PD (OR, 2.27; 95% CI, 1.206-4.298; P < 0.011). Significantly higher UPDRS (35.85 ± 1.35 and 32.09 ± 0.99, respectively, P = 0.023) and HY scores (2(1.5-2.5) and 1.5(1.0-2.0), respectively, P = 0.005) were present in patients with 25(OH)D level < 50 nmol/L compared to patients with 25(OH)D level ≥ 50 nmol/L. Despite some trends observed, differences in allelic and genotypic distribution between controls and patients, as well as between subgroups, did not reach the level of significance (P > 0.05).

Findings of this study confirm the hypothesis of a significant relationship between hypovitaminosis D and PD. We demonstrated higher prevalence of vitamin D deficiency in PD patients, as well as its predictive potential for the onset and progression of PD.