Generalized Sialic-Acid Storage Disease

A male infant born prematurely with fetal hydrops died suddenly at the age of 5 months with persistent hepatomegaly and abdominal ascites but no skeletal abnormalities. Alcian blue staining inclusions were noted in placental trophoblast and liver cells. Electron micrographs of liver and cultured skin fibroblasts revealed vacuolated cells with granular and floccular material within lysosomes. Lysosomal enzyme activities (including neuraminidase) in liver and fibroblast extracts were within normal limits. Analysis of aqueous extracts of autopsy brain and liver samples by gas liquid chromatography revealed large amounts of sialic acid; an average of 4.4pmole/g of brain and 21.0μmole/g liver. Normal tissues had undetectable amounts of this sugar. Gel filtration and thin layer chromatography confirmed that the major storage material was free sialic acid. Cultured skin fibroblasts incubated with [3H]glucosamine demonstrated an accumulation of a radioactive component with chromatographic properties and charge consistent with sialic acid. (Supported by NIH grants HD06426 and HD09402).