Application of a galactosylceramidase microassay method to early prenatal diagnosis of Krabbe's disease.

An enzymatic microassay method was devised to determine galactosylceramidase activities of microsamples prepared from primary cultures of amniotic fluid cells. A piece of freeze-dried cell mass (0.5--1 microgram dry weight) prepared from a colony on the bottom plate of a culture flask, was weighed and incubated in 4.02 microliter of the assay mixture. A small amount of galactose hydrolyzed from galactosylceramide was amplified about 10 000-fold and determined by using an enzymatic amplification reaction, NAD cycling. Microsamples were also prepared from freeze-dried leukocytes and skin fibroblasts. The present method was applied to prenatal diagnosis using amniotic cells as a sample in a case of high-risk pregnancy for Krabbe's disease. The result was confirmed by analysis of fibroblasts and organs from the aborted fetus.