A severe infantile mucolipidosis. Clinical, biochemical, and pathologic features.

We studied a case of severe infantile mucolipidosis that fell within the clinical spectrum of mucolipidosis I. A 2,100-g girl was delivered by cesarean section at 30 weeks' gestation, after the development of polyhydramnios. Tense ascites and hepatomegaly were present at birth and persisted until her death at age 4 months. Although she was growth retarded, no dysmorphic features were evident. Mucopolysacchariduria was absent, and no lysosomal enzyme deficiencies were identified in cultures of fibroblasts. N-acetyl neuraminidase was not included in the assay. Excessive intracellular accumulation of material within membrane-bound vacuoles was demonstrated in all tissues examined by light and electron microscopy. This material had histochemical and ultrastructural characteristics of both mucopolysaccharides and lipids. The placental trophoblasts, hepatocytes, neurons, glomerular epithelium, and mononuclear phagocytes were most affected.