In 1997 we proposed a novel lysosomal disease entity in a 11-year-old girl who had progressive fatal encephaloneuropathy. 1 Stromme P. Mansson J.E. Scott H. Skullerud K. Hovig T. Encephaloneuropathy with lysosomal zebra bodies and GM2 ganglioside storage. Pediatr Neurol. 1997; 16: 141-144 Abstract Full Text PDF PubMed Scopus (9) Google Scholar Hypotonia was present almost from birth, and a neuromuscular disease was suspected. From age two years, global deterioration became evident, with intractable seizures, dementia, muscle weakness with atrophy, and respiratory failure. Autopsy showed normal brain weight despite macroscopic atrophic changes, suggesting that atrophy could be secondary to abnormal storage. Electron microscopy examination of the spianl cord showed zebra body inclusions in the anterior horn neurons (Figure S1). Immunohistochemistry demonstrated that GM2 ganglioside, a sialylated oligosaccharide, bound to a hydrophobic lipid moiety, was a major constituent of the storage material (Figure S2). However, known GM2 gangliosidoses, such as Tay-Sachs and Sandhoff diseases, and other established lysosomal disorders with GM2 ganglioside accumulation, were excluded at the time.