In most families, TS and chronic tic disorders seem to follow an autosomal dominant pattern of inheritance, with varying degrees of penetrance. (13) Segregation analysis in large pedigrees has shown that penetrance is gender related. For males, penetrance is nearly complete when all tic disorders are included. For females, penetrance increases from 56% for tic disorders to 70% when OCD is included as part of the phenotypic expression of the TS gene(s).