Recent developments in the investigation of inherited metabolic disorders using cultured human cells

The purpose of this paper is to share experience with our systems and revie w recent "in vitro" methods using intact cells (fibroblasts, amniocytes) in which entire metabolic pathways can be probed for inherited metabolic defe cts reflected by elevations of intermediates determined by tandem mass spec trometry, HPLC, or gas chromatography-mass spectrometry. Currently, one can explore the integrity of mitochondrial fat oxidation, peroxisomal degradat ion of methyl-branched fatty acids (e.g., pristanate), and the mitochondria l degradation of the branched chain amino acids (leucine, valine, and isole ucine). For many of the diseases, the specific defect can be recognized fro m the acylcarnitine profile resulting from incubation of the intact cells w ith stable-isotope-labeled precursors to the particular pathway. This appro ach has also been successful in identifying new inherited metabolic disorde rs, biochemical correlation with clinical phenotypes of individual defects, and sequential oxidation of fatty acids by peroxisomal-mitochondrial inter action, (C) 1999 Academic Press.