Mental retardation, hypotonia, and generalized seizures associated with astrocytic "residual" bodies. An...

Two siblings suffering since birth from convulsions, hypotonia, and mental retardation are presented. In the older sibling (eight and one-half years of age) frontal lobe biopsy revealed abnormal cytosomes with lamellar profiles in astrocytes, macrophages, and to a lesser degree in neurons. Similar cytosomes have not yet been reported in cases of sphingolipidoses or in late infantile-juvenile amaurotic idiocy. These cytosomes stained intensely with silver proteinate, an ultrastructural cytochemical stain for carbohydrate moieties. In contrast, lipofuscin did not stain with silver proteinate. Multilamellar (crescentic curvilinear) cytosomes from a reported case of late infantile amaurotic idocy (Batten-Vogt-Spielmeyer disease) did not stain with silver proteinate. Abnormal cytosomes were not found in blood cells, liver, and peripheral nerve. In the younger sibling (14 months old) postmortem ultrastructural studies of cerebral tissue showed very few abnormal cytosomes. On the basis of the clinical and ultrastructural findings, we conclude that these two cases can be distinguished from those with multilamellar (crescentic-curvilinear) inclusions and from cases of the so-called "neuronal ceroid-lipofuscinosis" syndrome.