PT - JOURNAL ARTICLE AU - Steinberg, S J AU - Ward, C P AU - Fensom, A H TI - Complementation studies in Niemann-Pick disease type C indicate the existence of a second group. AID - 10.1136/jmg.31.4.317 DP - 1994 Apr 01 TA - Journal of Medical Genetics PG - 317--320 VI - 31 IP - 4 4099 - http://jmg.bmj.com/content/31/4/317.short 4100 - http://jmg.bmj.com/content/31/4/317.full SO - J Med Genet1994 Apr 01; 31 AB - Niemann-Pick disease type C is a clinically heterogeneous storage disorder with an unknown primary metabolic defect. We have undertaken somatic cell hybridisation experiments using skin fibroblast strains from 12 patients representing a wide clinical spectrum. Preliminary experiments using filipin staining of free cholesterol as a marker for complementation indicated the existence of one major group (group alpha) and one minor group (group beta) represented by one mutant strain. Subsequent experiments in which sphingomyelinase activity was measured as a marker for complementation using five mutant strains showing activity consistently < 40% control levels confirmed the existence of the second group.