Affected parent and age of onset in Huntington's chorea.

In a recent report, Merritt et al. (1969) searched the literature and their own material for cases of Huntington's chorea with onset before the age of 21.They found that when the disease began in child- hood or adolescence the history was generally on the father's side.In 89 out of 113 cases in which descent could be determined, the father or his relatives were affected.The sex ratio among the affected young people was essentially 1:1.In discussing their results Merritt et al. suggest, referring to Bell (1934), that female choreics have fewer children than male choreics; hence, in a representative sample of choreics, including juvenile cases, we should find that paternal predominates over maternal descent.However, in Bell's work roughly the same per- centages of male and female choreics failed to marry, and among those who did marry males and