Sanfilippo disease, type C: three cases in the same family.

Six siblings were followed, three of them suffering from a Sanfilippo disease, type C, as demonstrated by a deficient glucosamine acetyltransferase activity in cultured skin fibroblasts. Clinical and radiological findings were similar in the three affected children and the phenotypical expression of the disease allowed no distinction between the different types of Sanfilippo disease. Ultrastructural studies of the liver demonstrated characteristic intra-vacuolar inclusions.