ExomeChip-based rare variant association study in restless legs syndrome.

Restless legs syndrome (RLS) is a common sleep-related movement disorder in populations of European descent and disease risk is strongly influenced by genetic factors. Common variants have been assessed extensively in several genome-wide association studies, but the contribution of rarer genetic variation has not been investigated at this scale. We therefore genotyped a case-control set of 9246 individuals for mainly rare and low frequency exonic variants using the Illumina ExomeChip. However, standard single variant and gene-level association tests were negative. This does not preclude a role of rare variants in RLS, but is likely due to the small sample size and the limited selection of rare genetic variation captured on the array. Therefore, exome or whole genome sequencing should be performed rather than increasing the sample size of ExomeChip studies in order to identify rare risk variants for RLS.