A family study of Tourette syndrome in Japan

Although the mode of inheritance remains in doubt, twin and family studies conducted mostly in the United States and western Europe suggest that genet ic factors play an important role in the transmission and expression of Tou rette syndrome (TS), In an effort to evaluate population-based genetic diff erences, we generated risk estimates for first-degree relatives of TS proba nds in Japan using methods similar to those utilized in recent Western. stu dies. The subjects were 52 TS probands seen at an outpatient clinic of Toky o University Hospital and their 165 first-degree relatives. All probands an d one or more first-degree relatives in each family were interviewed concer ning the presence of tic and obsessive-compulsive symptoms by expert clinic ians. The age-corrected rates of TS, chronic motor ties, obsessive-compulsi ve disorder, and subclinical obsessive-compulsive symptoms in the first-deg ree relatives were 2.0%, 12.0%, 1.6%, and 7.0%, respectively. Rates of TS a nd related disorders in Japan appear to be much lower than those in recent Western family studies. If replicated, these data suggest that there may be differences in the nature and frequency of vulnerable alleles for TS and r elated disorders in the Japanese compared to European populations. (C) 2001 Wiley-Liss, Inc.