GM1-gangliosidosis type 1 involving the cutaneous vascular endothelial cells in a black infant with multiple ectopic Mongolian spots.

GM1-gangliosidosis (GM1) is one of the metabolic storage diseases, of which a differential diagnosis requires an array of biochemical assays to determine the enzyme deficiency. This approach is not only time-consuming and costly but also unavailable to most hospital laboratories. However, a presumptive diagnosis of GM1 may be made on the basis of coarse facial feature, foamy endothelial cells in the cutaneous blood vessels and ectopic Mongolian spots, if present. A more definitive diagnosis of GM1 is then made on the demonstration of deficiency of GM1 beta-galactosidase in leukocytes, plasma or cultured skin fibroblasts. Thus, a battery of enzyme tests may be averted.