Infantile sialic acid storage disease (ISSD). Report on first case in Czech Republic with biopsy and autopsy findings.

The first case of infantile sialic acid storage disease in Czech Republic is presented in a four-and-half year-old girl. The clinical phenotype consisted of moderate hepatosplenomegaly and skin hypopigmentation, early psychomotoric and developmental arrest, associated with truncal ataxia and lower extremities spasticity, extinguished acoustic and visual perception (optic atrophy without macular alteration) and remarkable automutilation phenomena. The appearance was normosomatic and there were minimal dysostotic changes. Skin and liver biopsy displayed moderate amount of lucent storage lysosomes in epithelial, mesenchymal, and neural elements. Alder-Reily granules were found in the bone marrow and peripheral blood cells. The urinary excretion of mucopolysaccharides and oligosaccharides was not increased. The autopsy showed heterogenous neuronal and glial brain storage (lucent lysosomes, lipopigment, membranous cytoplasmic bodies), severe hypomyelination and severe storage in the splenic sinus endothelium. Diagnosis was made by proving thirteen fold increase of free sialic acid in the fibroblast culture. It is pointed out that in the case of a mucopolysaccharidosis-like storage disease unexplainable by a hydrolytic enzyme deficiency, it is the enzyme product storage which must be suspected. At present, the only candidate is the sialic acid storage disease.