Recently a novel case of angiokeratoma corporis diffusum with glycoaminoaciduria was described in a 46-yr-old Japanese woman. Known causes of the cutaneous manifestation were eliminated by enzyme analyses, and further characterization of the accumulated urinary O-linked sialopeptides revealed identity to those excreted by patients with an infantile neuroaxonal dystrophy due to lysosomal α-N-acetylgalactosaminidase deficiency. Investigation of the α-N-acetylgalactosaminidase activity and protein in the proband revealed less than 2% of normal activity and the absence of detectable immunoreactive enzyme protein, findings comparable to those in the patients with infantile neuroaxonal dystrophy and α-N-acetylgalactosaminidase deficiency. In addition, the proband's unaffected offspring had half-normal levels of α-N-acetylgalactosaminidase activity, consistent with this enzymatic deficiency being the primary metabolic defect in this autosomal recessive trait. Ultrastructural examination of skin and blood cells from the adult proband revealed the presence of prominent lysosomal inclusions containing diffuse amorphous and filamentous material. In contrast, these morphologic findings were not observed in the nonneural tissues from patients with infantile neuroaxonal dystrophy and α-N-acetylgalactosaminidase deficiency. These studies document the occurrence of two forms of α-N-acetylgalactosaminidase deficiency and sialopeptiduria, a severe infantile-onset form of neuroaxonal dystrophy without angiokeratoma or visceral lysosomal inclusions and an adult-onset form characterized by angiokeratoma, extensive lysosomal accumulation of sialoglycopeptides and the absence of detectable neurologic involvement.
- Angiokeratoma corporis diffusum
- Lysosomal hydrolase