In 1975 a new caprine neurovisceral storage disease was identified in related Nubian goats in Michigan (Jones, M. Z., Cunningham, J. G., Dade, A. W., and Alessi, D. M. (1979) Soc. Neurosci. Abstr. 5, 513). The affected kids of both sexes showed profound neurological deficits at birth, lack of myelination in cerebral hemispheres and cerebellum, axonal lesions, and cytoplasmic vacuolation. A similar genetic syndrome arose independently in a population of Anglo-Nubian goats in New South Wales (Hartley, W. J., and Blakemore, W. F. (1973) Acta Neuropathol. 25, 325-333). Preliminary chemical characterization of an accumulated metabolite was performed. An extract of 1 g of brain from an affected goat was found to contain 2.2 mumol of the trisaccharide Man (beta 1 goes to 4)GlcNAc(beta 1 goes to 4)GlcNAc (beta-mannosylchitobiose). The accumulation of this substance suggests the possibility of a genetic defect in beta-mannosidase in the catabolic pathway for N-linked complex glycopeptides and would be the first indication of a beta-mannosidosis.