Hereditary amyotrophic lateral sclerosis.

A Spanish family transmits, as an autosomal dominant trait, a form of amyotrophic lateral sclerosis characterized by an unusually prolonged evolution of the disease in all affected members. Precocity and persistence of muscle cramps, presence of unilateral proximal segmental myoclonus and early abolition of ankle jerks are other clinical features conspicuous in this family. This type of hereditary ALS of non-chamorro origin and prolonged evolution is rare.