Tremor asymmetry did not aggregate in families with essential tremor (ET), a recent study found. Therefore, this does not seem to be a disease feature that is heritable. ET probands and relatives were enrolled in a genetic study at Yale and Columbia universities. An in-person evaluation consisted of a videotaped neurological examination, including a detailed assessment of tremors. A senior movement disorders neurologist reviewed all videotaped examinations, and the severity of postural and kinetic arm tremors was rated on 12 examination items using a reliable rating scale. There were 187 enrollees (59 probands, 128 affected relatives). Researchers found:

• In a bivariate linear regression model, the tremor asymmetry index in the proband was not a predictor of the tremor asymmetry index in their relatives.
• In an analysis of variance, family grouping did not explain a significant proportion of the total variance in the tremor asymmetry index.