The genetic contributions to the expression of myoclonus in 7 inbred strains of mice. The mean latency to the first myoclonic jerk (black bars) and the mean number of myoclonic jerks preceding a generalized seizure (red bars) following one exposure to flurothyl in DBA/2J, C57BL/6J, C57BLKS/J, 129S1/SVlmJ, A/J, BALB/cJ, and C3H/HeJ mice. * denotes significantly different from C3H/HeJ mice (P < 0.009); $ denotes significantly different from C57BL/6J mice (P < 0.05).