Parental factors associated with rigidity in Huntington's disease.

The discriminatory power of ten factors has been explored in relation to the presence or absence of muscular rigidity in patients with Huntington's disease. The sex and neurological sign of an affected parent were the only two significant determinants of rigidity or choreoathetosis in offspring. It was shown, using the Mantel-Haenszel method of adjusting for confounding variables that the risk of a patient displaying rigidity (and thereby having a graver prognosis) is five times as great for those with rigid parents as it is for those with non-rigid parents. Additionally, the risk of a patient displaying rigidity is more than three times as great for those with affected fathers as it is for those with affected mothers. Some implications of these findings are discussed.