Infantile neurodegenerative disease with neuronal accumulation of phosphorylated neurofilaments.

A caucasian male with a history of mental retardation and intractable epilepsy since birth, developed progressive wasting and weakness of skeletal muscles, leading to death at 4 years of age. A biopsy of gastrocnemius muscle at 2 years of age revealed severe neurogenic atrophy. Sural nerve biopsies at 2 and 3 years showed progressive atrophy and loss of large myelinated nerve fibers with a paucity of neurofilaments in remaining nerve fibers. Postmortem immunohistochemical and ultrastructural examination showed that neurons were markedly distended by phosphorylated neurofilaments. Whereas large lower motor neurons were most severely involved, dorsal root ganglia and neurons in the cerebral cortex and deep gray nuclei were also affected. It is suggested that this disease is caused by a disorder of neurofilament phosphorylation and transport.