Derangements of oxidative metabolism are found in glutaric aciduria type II (GA-II), ethylmalonic-adipic aciduria (EMA) and dicarboxylic aciduria (DCA). Dehydrogenation of multiple straight- and branched-chain acyl-CoA's is defective in GA-II and in EMA, a mild form of GA-II. Deficiency of either the electron transferring flavoprotein (ETF), or the Fe-S flavoprotein, ETF dehydrogenase, may cause GA-II and EMA. Mitochondria isolated from GA-II and EMA fibroblasts or lymphoblasts will be assayed for acyl-CoA dehydrogenases (ADH), ETF, and ETF dehydrogenase by spectrophotometric, fluorometric, radioisotopic, and electron paramagnetic resonance methods. 14C-substrate oxidation studies with cells from family members and complementation studies will delineate complementation groups and the modes of inheritance of these two disorders. A GA-II family demonstrating mixed X-linked recessive/autosomal recessive inheritance will be investigated in detail. In DCA, medium chain ADH activity is deficient in the mitochondrion; ADH activities will be further assayed in DCA cells with tritium release assays. Family and complementation studies will also be performed. 14C-substrate oxidation, ADH and ETF levels and FAD and riboflavin metabolism will be studied in riboflavin-depleted and -supplemented cells from two patients, one with riboflavin-responsive DCA/EMA and one with a riboflavin-responsive lipomyopathy. Since peroxisomal Beta-oxidation is an alternative pathway of fatty acid oxidation, we will study how Clofibrate, which produces peroxisomal proliferation, increases acyl-CoA catabolism and ADH and ETF levels in DCA cells. The effects of the cofactor carnitine on fatty acid metabolism in GA-II, EMA and DCA cell lines will also be determined. Deficient catabolism of pipecolic acid (PIP), a putative neurotransmitter, may play a role in the pathogenesis of two similar neurodegenerative disorders, hyperpipecolic acidemia (HPA) and Zellweger syndrome (ZS). Using 3H- or 14C-labeled PIP, the conversion of PIP to Alpha-aminoadipate and piperidine will be studied in tissue slices, intact cells, homogenates and subcellular organelles from rabbit brain, kidney and liver, as well as in cultured rabbit neuronal cells; the PIP metabolites will be resolved by high pressure liquid or paper chromatography. After completion of these preliminary studies, similar experiments will be performed with fibroblasts, lymphoblasts and tissues obtained post mortem from normal controls and infants with HPA and ZS.
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