Generalized gangliosidosis type II (juvenile GM1 gangliosidosis). A pathological, histochemical and ultrastructural study.

Pathological, histochemical and ultrastructural studies on 3 siblings with GM1 gangliosidosis type II are reported. These studies support a biochemical defect with profound deficiency of beta-galactosidases which results in widespread accumulation of the GM1 ganglioside and its asialo derivative in brain and to a lesser extent in viscera, as well as in storage of a keratan sulphate-like mucopolysaccharide. Striking valvular changes in the heart without myocardial involvement were seen in all cases. The histochemical and ultrastructural changes are similar to those seen in GM1 gangliosidosis type I, though less severe. Autosomal recessive inheritance without apparent ethnic predilection seems likely.