VDR Gene Polymorphisms and Cluster Headache Susceptibility: Case-Control Study in a Southeastern European Caucasian Population.

Cluster headache (CH) is a severe primary headache disorder with a genetic component, as indicated by family and twin studies. Diurnal and seasonal rhythmicity are key features of the disease and might be related to vitamin D, as low vitamin D levels have been observed in patients with cluster headache. In addition, the vitamin D receptor (VDR) occurs in brain areas and particularly in the hypothalamus. The aim of the present case-control study was to investigate the association of cluster headache susceptibility and clinical phenotypes with the VDR gene polymorphisms FokI, BsmI and TaqI in a Southeastern European Caucasian population. DNA was extracted from 131 unrelated CH patients and 282 non-headache controls and genotyped using real-time PCR (melting curve analysis). Linkage disequilibrium (LD) analysis confirmed that BsmI and TaqI, both located in the 3'UTR of the VDR gene, are in strong LD. Genotype and allele frequency distribution analysis of the VDR FokI, BsmI, and TaqI polymorphisms showed no statistically significant difference between cases and controls, whereas haplotype analysis indicated that the TAC haplotype might be associated with decreased cluster headache susceptibility. Intra-patient analysis according to diverse clinical phenotypes showed an association of the BsmI GG and TaqI TT genotypes with more frequent occurrence of CH attacks in this cohort. Therefore, a possible association was observed between VDR gene polymorphisms BsmI and TaqI or a linked locus and susceptibility for cluster headache development and altered clinical phenotypes in the Southeastern European Caucasian study population. Further large-scale replication studies are needed to validate these findings.