Ultrastructure of rectal biopsy specimens in unusual familial ataxia with cerebrospinal fluid abnormality.

The ultrastructure of rectal biopsy specimens from a 60-year-old woman of unusual familial ataxia with cerebrospinal fluid abnormality was investigated. She had two male siblings similarly affected and a close consanguinity in the family. Meissner's plexus neurons, Schwann cells, fibroblasts and smooth muscle cells within the rectum contained intracytoplasmic eosinophilic inclusions (IEIs) with or without intensely eosinophilic granules. Ultrastructurally the IEIs were composed of a membrane-bound, fine granular material with or without dense cores. The IEIs resembled intracytoplasmic inclusions seen in various cells of the central nervous system from a male autopsied sibling. The clinically and morphologically similar finding in the two siblings suggests an autosomal recessive inherited metabolic disorder previously unreported.