Chronic spinal muscular atrophy

For many years, neurologists have been aware of the occasional occurrence of motor neurone disease of prolonged duration. Although the aetiology of this disease is still unknown, the descriptions of hereditary amyotrophic lateral sclerosis (reviewed by Espinosa, Okihiro, Mulder, and Sayre, 1962) and the high incidence of motor neurone disease occurring in the Chamorros of the Mariana Islands, with and without the Parkinsonism-dementia syn-drome, have reawakened interest in these disorders with particular regard to a possible genetic aetiology