[Study of plasma acylcarnitines using tandem mass spectrometry. Application to the diagnosis of metabolism hereditary diseases]

Acetyl-4'-phosphopantetheine is stable in serum and prevents phenotypes induced by pantothenate kinase deficiency

Coenzyme A is an essential metabolite known for its central role in over one hundred cellular metabolic reactions. In cells, Coenzyme A is synthesized de novo in five enzymatic steps with vitamin B5 as the starting metabolite, phosphorylated by pantothenate kinase. Mutations in the pantothenate kinase 2 gene cause a severe form of neurodegeneration for which no treatment is available. One therapeutic strategy is to generate Coenzyme A precursors downstream of the defective step in the pathway. Here we describe the synthesis, characteristics and in vivo rescue potential of the acetyl-Coenzyme A precursor S-acetyl-4′-phosphopantetheine as a possible treatment for neurodegeneration associated with pantothenate kinase deficiency.

Evaluation of brain long-chain acylcarnitines during cerebral ischemia

Concentration and distribution of long-chain acylcarnitines in control microwaved and ischemic (decapitated) rat brain were measured by electrospray ionization tandem mass spectrometry. The total acylcarnitine concentration from control rat brains equaled 7-8 nmol/g wet weight brain, about one-fourth the total concentration of long-chain acyl-CoA, indicating a small role in buffering the total acyl-CoA pool concentration. Furthermore, acylcarnitine did not differ between ischemic and control rat brain with regard to total concentration or concentrations of molecular species of acylcarnitine. Therefore, the size of the acylcarnitine pool in brain is not affected by the dramatic increase in unesterified fatty acids (approximately 4x) that occurs in ischemia.

Carnitine-acylcarnitine translocase deficiency

Carnitine-acylcarnitine translocase deficiency, like other defects of mitochondrial fatty acid oxidation, is an autosomal, recessively inherited disorder. When the deficiency is near total, it is usually fatal, affects life soon after birth, and constitutes one of the causes of skeletal muscle myopathy, cardiac and liver abnormalities, and childhood sudden death. The presenting features have included neonatal distress, convulsions, hypoglycemia, hyperammonemia, hypoketonemia, intermittent dicarboxyluria, hypothermia, apnea, neurological deterioration, and hypocarnitinemia with grossly elevated acylcarnitines. Two cases of partial translocase deficiency (4-6% residual activity) with milder symptoms and without cardiac involvement have also been identified. Evidence so far indicates that the translocase protein is the product of a single gene. In two cases of translocase deficiency, the accompanying mutations have been identified. The benefits of prenatal diagnosis have been provided to the affected families by assays of the translocase and/or fatty acid oxidation in cultured amniotic/villous cells. In one such case genetic counseling was made possible even when the only specimen available from a deceased sibling was the Guthrie card.