Mild phenotypic expression of α‐N‐acetylgalactosaminidase deficiency in two adult siblings

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Abstract
Two adult siblings with an α-N-acetylgalactosaminidase deficiency are described. The patients' major features are massive lymphoedema and angiokeratoma corporis diffusum. Neurological evaluation performed in one of the patients was considered within normal limits. Blood type is A positive in each case. Ultrastructural examination of skin revealed numerous vacuoles in endothelial cells and pericytes. Fibroblast activity of α-N-acetylgalactosaminidase was decreased to 0.6–2% of mean normal value. Chromatography of urinary oligosaccharides showed abnormal bands identical to those excreted by two infantile patients with Schindler disease. The bands were identified as sialyloligosaccharides, and gas chromatography revealed the presence ofN-acetylgalactosamine-rich compounds accounting for 30% of the total monosaccharide content of the oligosaccharide fraction. These findings confirm the heterogeneity of α-N-acetylgalactosaminidase deficiency and emphasize the need to consider this lysosomal storage disease in the differential diagnosis of patients with angiokeratoma.