Variable number tandem repeats in dopamine receptor D4 in Tourette's syndrome

Background We attempted to clarify the association between dopamine receptor D4 (DRD4) 48-bp variable number of tandem repeats (VNTR) polymorphism and Tourette's syndrome. Methods The DRD4 48-bp VNTR polymorphism was genotyped in 291 Tourette's syndrome patients (including 218 trios) and 405 controls. Chi-square and transmission disequilibrium test analysis were used to compare genetic distributions. We retrieved related studies in a meta-analysis to clarify the role of 2-repeat and 4-repeat alleles in the pathogenesis. Results Obvious genotype and allele distribution differences were observed between patients and healthy controls for both 2-repeat and 4-repeat alleles. This was verified using transmission disequilibrium test analysis. Meta-analysis showed strong associations in both the total population and the Asian population. Conclusions The DRD4 48-bp VNTR polymorphism appears to be associated with Tourette's syndrome, with the 2-repeat allele performing a protective role and the 4-repeat allele a nonprotective role in the genesis of the disease. © 2014 International Parkinson and Movement Disorder Society