Age at onset, age at diagnosis, and phenotypic expressions of TS were compared in the offspring of affected males and females among 437 first degree relatives of 57 probands studied at Academic Department of Psychiatry, University College London Medical School, London, UK. Maternally transmitted cases had an earlier age at onset, suggesting a genomic imprinting effect on the expression of TS. 
COMMENT. Family history data on Tourette syndrome cases must be evaluated for maternal or paternal transmission. Mothers affected with TS are likely to have affected offspring with an earlier age at onset. Environmental factors, such as exposure to stress or cocaine, may be alternative explanations for this finding.
Developmental Basal Ganglia Syndrome. Failure to distinguish TS from other causes of DBGS may explain confusion in localizing the genetic defect in TS, determining prevalence, and assessing therapy, according to a report from the University of Rochester, NY . Causes of the DBGS include primary (hereditary) tic disorders, obsessive-compulsive disorder, ADHD, Huntington disease, and secondary (symptomatic) autism, mental retardation, intrauterine drug exposure, perinatal asphyxia, encephalitis, head trauma, etc.