A twin study of Tourette syndrome.
In 43 pairs of same-sex twins, in which at least one co-twin had Tourette syndrome (TS), 30 pairs were probably monozygotic (MZ) and 13 were probably dizygotic (DZ). Concordances for TS were 53% and 8% for MZ and DZ pairs, respectively. When diagnostic criteria were broadened to include any tics in co-twins, concordance rates were 77% and 23% for MZ and DZ pairs, respectively. These concordances are consistent with genetic etiology. However, the fact that only 53% of MZ twins were fully concordant indicates nongenetic factors affect expression of TS. Presence of tics in discordant co-twins and timing of onset in partially concordant co-twins support an association between TS and tics in families with TS present. The data are inconclusive on whether some MZ twins with discordant co-twins are etiologically different from those who are concordant.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D004200:Diseases in Twins; D005260:Female; D006220:Haloperidol / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D013981:Tic Disorders / Q000175:diagnosis / Q000235:genetics; D005879:Tourette Syndrome / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
D006220:Haloperidol