CANADIAN RESTLESS LEGS SYNDROME TWIN STUDY

Abstract

Restless legs syndrome (RLS) is a common sensorimotor disorder1 where familial aggregation strongly suggests an important genetic component. However, the underlying genetic structure remains largely unknown. Due to its recent acceptance as a clinical entity and the development of standard diagnostic criteria and reliable assessment instruments,1 few and incomplete RLS twin studies have been published.2,3 ### Methods. A validated 36-item RLS questionnaire, used for our family studies of RLS4 and reformatted to be self-administered, and a standard zygosity questionnaire were individually mailed to 600 adult co-twins (age 18 years and older) from the University of British Columbia (UBC) twin registry across Canada.5 An additional 86 co-twins were identified through our family studies in Quebec (Universite de Montreal [UdeM]) and were telephone interviewed by a trained research associate using the same questionnaires. The pairs with mean zygosity scores of ≥4 were classified as monozygotic (MZ) and all others as dizygotic (DZ).6 Only individuals fulfilling all four diagnostic criteria1 were classified as definite RLS; individuals missing one essential diagnostic criterion but having one or more supporting …