Electromyographic studies in parents of children with spinal muscular atrophy.

Electromyographic studies have been carried out on the quadriceps and deltoid muscles of a number of healthy parents of children with infantile spinal muscular atrophy (types I and II) and the results compared with those obtained in healthy controls of the same sex. The results indicated an increase in mean amplitude of action potentials in quadriceps and deltoid muscles in both fathers and mothers (statistically significant in the quadriceps in the latter) of children with type I spinal muscular atrophy (Werdnig-Hoffmann disease). Increase in the mean amplitude in the quadriceps and deltoid muscles in mothers of children with type II spinal muscular atrophy and the mean duration of action potentials in the quadriceps muscle in mothers of children with type I and type II spinal muscular atrophy were also observed, but the differences from controls were not significant.