Analysis of CAG repeat expansions in restless legs syndrome

Abstract

Study Objectives: A relatively high prevalence of restless legs syndrome symptoms has been recently reported in a substantial proportion of patients affected with spinocerebellar ataxia type 3. Our aim was to investigate whether there is a common genetic etiology between restless legs syndrome and spinocerebellar ataxia type 3. Design: Systematic differences in the number of spinocerebellar ataxia type 3 trinucleotide repeat were investigated by means of an association study. The relationship between the size of the expanded alleles and several clinical features was also considered. Participants and Setting: 125 extensively characterized restless legs syndrome patients compared with 188 healthy controls matched for ethnic background. Interventions: N/A Measurements and Results: No CAG repeat expansions in the pathologic or intermediate range were detected in any of the examined subjects, including patients and controls. A similar allelic distribution was observed in both groups (Mann-Whitney U test = 78406; P = 0.99). Moreover, stratification analyses of the patients' samples according to different clinical and polysomnographic variables disclosed no significant differences. Conclusions: These results do not provide evidence toward an involvement of large CAG trinucleotide expansions at the spinocerebellar ataxia type 3 locus in idiopathic restless legs syndrome.