ABSTRACT
Although the familial nature of Tourette’s syndrome (TS) has been observed since 1885 by Gilles de la Tourette himself, it was not until the late 1970s that studies (1,2) demonstrated an increased frequency of a positive family history of tics in families of TS patients. These early studies did not estimate rates of illness among relatives. The first study to do so was reported byKidd et al. (3). This study combined TS and chronic tics (CT) into a single category and showed that the risk to relatives was significantly elevated over what would be expected by chance.
