Neuronal intranuclear inclusion disease in identical twins.

A pair of female identical twins exhibited slurred speech, nystagmus, and oculogyral spasms starting at age 11. The patients then had episodic rage, extrapyramidal and lower motor neuron abnormalities, and grand mal seizures, but retained largely normal intelligence, until death at age 21. Severe loss of nigral and craniospinal motor neurons was noted postmortem. Round, eosinophilic, autofluorescent inclusion bodies, 3 to 10 microns in diameter, were observed in the nuclei of most nerve cell types of the central and peripheral nervous systems and retina. Ultrastructurally the inclusions appeared as masses of filaments without a limiting membrane, the constituent filaments having a diameter of 8.5 to 9.5 nm. Histochemical results suggested the presence of proteins with a high content of tryptophan. Four similar cases have been reported previously under various designations. We propose the name neuronal intranuclear inclusion disease for the disorder.