A case of neuraminidase deficiency associated with a partial beta-galactosidase defect. Clinical, biochemical and radiological studies.

Neuraminidase deficiency towards fetuin, 2 leads to 3 sialyllactose and 2 leads to 6 sialyllactose was found in cultured skin fibroblasts from a 10-year-old Japanese girl who exhibits craniofacial dysmorphism, a short neck, vertebral and pelvic deformities and macular cherry-red spots. Neuraminidase deficiency in this case seems the primary enzyme defect because the enzyme activity of her parents was intermediate. In addition, beta-galactosidase in leukocytes and cultured skin fibroblasts from the patient was found to be severely deficient, but could be detected in serum and urine. In the parents, beta-galactosidase activity was normal. There were moderately increased levels of urinary sialic acid-rich oligosaccharides and glycopeptides in the patient. The clinical and biochemical observations suggest that this case is very close to mucolipidosis I.