LCHAD and MTP Deficiencies - Two Disorders of Mitochondrial Fatty Acid β-Oxidation with Unusual Features

Mitochondrial fatty acid β-oxidation disorders are relatively common causes of acute metabolic crises and sudden death in infants. Most of these disorders can be treated effectively, provided, fasting is avoided and there is an early start of a high-carbohydrate low-fat diet therapy. Two disorders, long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) and complete mitochondrial trifunctional protein (MTP) deficiencies, have pathogenetically interesting and therapeutically challenging manifestations, which are atypical of β-oxidation defects. In addition to the classical manifestations of disorders affecting β-oxidation of long-chain fatty acids (hypoketotic hypoglycaemia, hepatopathy, cardiomyopathy and rhabdomyolysis), patients with LCHAD and MTP defects have pigmentary retinopathy, which causes visual handicap, progressive peripheral neuropathy and hypoparathyreosis. Furthermore, female carriers may have devastating pre-eclampsia-related complications and in particular acute fatty liver during pregnancy. Pathogenesis research of the important characteristic features of LCHAD and MTP deficiencies would not only improve opportunities for new therapeutic strategies but could increase our understanding of tissue metabolism affected by these disorders.