High performance liquid chromatography for the detection of homozygotes and heterozygotes of Niemann-Pick disease.

A method is developed for the detection of homozygotes and heterozygote carriers of Niemann-Pick disease type A by employing a high performance liquid chromatography (HPLC) technique for the measurement of sphingomyelin (SP) as well as for the assay of the enzyme sphingomyelinase (SPase) in skin fibroblasts and amniotic fluid cell cultures. A simple, less than 10-min, HPLC of the lipid extract of fibroblasts (about 2 x 10(6) cells) and measurement of the ratio of the area of SP peak to that of other phospholipids present in the cell-lipid extract show accumulation of SP in Niemann-Pick type A fibroblasts compared to normal. The SPase assay was performed by HPLC measurement of the substrate SP before and after hydrolysis by the enzyme. By employing this technique, it was shown that cells from patients with Niemann-Pick disease type A have less than 10% of the normal SPase activity, whereas the heterozygote carriers of this disease have about 50% of the normal activity.