BackgroundThe study tested specific hypotheses that (a) there is an increased incidence of psychiatric disorders in asymptomatic heterozygotes for Huntington's disease (HD) compared with the normal homozygotes, and (b) there is an increased incidence of psychiatric disorders in the adult offspring of Huntington's disease patients compared with their partners.MethodA controlled study was made of 93 apparently healthy individuals (at 50% risk), who had given DNA samples for the predictive test, and 70 of their partners. Current and past psychopathology was assessed and compared with the DNA predictive test results based on linkage analyses. The results of psychiatric assessments of the two groups were compared.ResultsDNA test results were available for 53 subjects (of 93). Five subjects at risk for HD were omitted from the study. The asymptomatic heterozygotes (n = 20) showed no significant increase in the incidence of any psychiatric episode, depression, schizophrenia or behavioural disorder when compared with the normal homozygotes (n = 33). The whole tested group showed a significantly greater number of psychiatric episodes than their partners (n = 43).ConclusionsAsymptomatic HD gene carriers do not have a greater incidence of psychiatric disorders than the non-gene carriers born to a HD parent.