CONFERENCE
OF THE CANADIAN SOCIETY OF CLINICAL CHEMISTS liver and significant cardiomegaly with myocardial muscle cell lipid accumulation. Skeletal muscle appeared normal. Organic acid analysis by GC/MS on post-mortcm urine showed a remarkable increase in saturated and unsaturated dicarboxyfic acids, most notably those in the range from C6 to C14 which suggested impaired beta-oxidation. ReU~spective analysis of acylcaruitines by tandem MS on blood spots obtained from the neonatal screening card showed elevated C14:1, C14"2, C16, C18:1 acylcaruitines, and were suggestive of very long chain scyl CoA dehydrogenase (VLCAD) deficiency. The pattern of metabolites appears most typical of VLCAD deficiency, but defmitive diagnosis awaits enzymic analysis. It is known that metabolism of very long chain fatty acids (VLCFA) largely occurs in the peroxisom~, however, this case confirms that mitochondria also have an important talc in VLCFA metabolism, since VLCAD is a membrane-bound mitochondrial enzyme. Inborn errors involving fatty acid oxidation should be considered in all infants with hypertrophic or dilated cardiomyopathy. In addition, these results serve to emphasize the diagnostic value of neonatal blood cards for confirmation and for neonatal screening.