Reproduction and age of onset of Huntington's disease in Tasmania.

This study demonstrates that in Tasmania, individuals born before 1930, with an onset of Huntington's disease (HD) after the mean age of onset, were significantly more fertile than their unaffected siblings and the general population. This applied to both sexes. The mean parental age of men with late-onset disease was significantly greater than that of their unaffected male siblings. The clinical implication is that those individuals at 50% risk of late-onset HD who have achieved their desired family size should be offered sterilisation.