A simple fluorescence assay was used to detect cells from patients with sphingolipidoses in a masked study at the Mayo Clinic, Rochester, MN. Replicate samples of 25 of 26 unique cell lines representing ten different lipid-storage diseases (Fabry’s disease, gangliosidoses (Tay-Sachs and Sandhoff forms), metachromatic leukodystrophy, mucolipidosis type IV, Niemann-Pick disease (types A, B, and C), and sphingolipid-activator-protein-precursor (prosaposin) deficiency), and 18 of 20 unique cell lines representing controls were correctly identified. The sensitivity was 96.2% and the specificity 90%.
The artificial fluorescent lipid, a derivative of the natural sphingolipid, lactosylceramide, accumulated in the lysosomes of cultured fibroblasts from patients with sphingolipidoses. It was mainly confined to the Golgi complex in normal control cells and cells from patients with other types of lysosomal diseases. With increasing concentrations in the membranes of the lysosomes, the emission of the fluorescent lipid changed from green to red wavelengths. The method should be useful as an initial general screen for lipid-storage diseases, and it may also allow screening of candidate drugs to treat the lipidoses. 
COMMENT. This simple fluorescence assay should be helpful in the investigation of children with developmental disorders and progressive neurodegenerative diseases and the exclusion of sphingolipid-storage diseases in patients with atypical or mild variants.
In a commentary by Bryan Winchester, Institute of Child Health, London , the method is described as potentially an important advance. He suggests that adaptation of the method to allow measurement of the fluorescence using microtitre-plate technology in whole cells, preferably white blood cells, would simplify the procedure and avoid the delay and cost of culturing fibroblasts.