Genetical components of physiological tremor.

Pysiological tremor was measured in 14 pairs of monozygotic twins, 14 pairs of dizygotic twins, and 14 pairs of control subjects matched for age and sex. Postural finger tremor was measured in each pair using a sub-miniature accelerometer and subjecting the amplified signals to power spectral analysis. Significant genetical influences were found for the proportion of tremore at frequencies near the peak frequency of 9-10 Hz. No genetical effects were found at other frequencies or for the absolute amount of tremore. The results suggest that physiological tremor between 8 and 13 Hz is genetically influenced and that tremor at these frequencies is determined by different mechanisms than those at other frequencies.