Two siblings, including a fetus, with Tay-Sachs disease.

This report consists of a morphological study on two siblings of Tay-Sachs disease. One is a girl of 3 years of age and the other is a 23-week fetus. In the first case, the nerve cells in the cerebral cortex showed histochemically abnormal accumulation of glycolipids and electron microscopically numerous membranous cytoplasmic bodies characteristic to gangliosidosis. In the fetal case, the nerve cells in the brain stem were well differentiated and here abnormal inclusions were found by histochemical study. The cortical neurons were immature in structure and inclusions were not demonstrated by histochemical study. In electron microscopic study, the cortical neurons also showed a small number of intracytoplasmic inclusions which contained electron dense granules and/or membranous structures. Causes of the differences in amount of abnormal lipid accumulation in the brain stem and the cerebral cortex were discussed.