Finally, possible genetic links between PD and RLS (the presence of allele 2 of the complex microsatellite repeat Rep1 within the α-synuclein gene promoter) and between Tourette syndrome and RLS (several variants in the <i>BTBD9</i> gene) have been reported in 2 case-control association studies, although these data, based on preliminary data with small sample sizes, need to be replicated in further studies.
Despite results of several recent case-control association studies which have suggested a possible contribution of heme-oxygenase 1 (HMOX1) rs2071746 and vitamin D3 receptor (VDR) rs731236 variants, or the presence of allele 2 of the complex microsatellite repeat Rep1 within the alpha-synuclein (SNCA) gene promoter in modifying the risk for RLS, these studies need to be replicated in further studies involving different populations.
We now observed this Rep1 allele 2 to show significantly decreased frequency in restless legs syndrome (RLS) in a genotyping study of 258 patients versus 235 healthy controls from Germany.