The relation of the sex of choreic and rigid subjects to the age at onset of Huntington''s disease

In a series of non-adult cases of Huntington's disease largely ascertained from the literature, the male sex-ratio increased linearly with onset age from 0.5 in the 0–5 years age-group to 1.15 in the 16–20 years age-group. When cases were separated according to the presence or absence of muscular rigidity, the same effect was observed among rigid subjects; the mean onset age for males significantly exceeded that for females.
In the absence of rigidity, typically choreic cases showed a different type of sex variation with age of onset. The crescent-shaped curve found was accentuated in those who inherited the disorder from their fathers so that females exceeded males over most of the reproductive period. The converse tended to apply to cases of maternal descent. A later onset age of maternal than paternal cases was found to be associated with this parental difference. It was speculated that hormonal factors may play a part in determining the sex differences observed.