Mitochondrial trifunctional protein (MTP) deficiency is an autosomal recessive disorder of mitochondrial fatty acid oxidation. Trifunctional protein acts as enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase and 3-cetothiolase for long chain fatty acids. It is located in the mitochondrial internal membrane. Main clinical signs include hypoketotic hypoglycemia in infancy or early childhood, along with hypotonia and often fatal hypertrophic cardiomyopathy, or sudden unexplained death. Later onset forms of the disease have been described, with peripheral neuropathy and episodes of rhabdomyolysis or muscular weakness related to myopathy. Measurement of plasmatic acylcarnitines and sometimes chromatography of urinary organic acids can help to orientate the diagnosis, but these methods to not allow differentiation between mitochondrial trifunctional protein deficiency and LCHAD (Long-chain 3-hydroxyacyl-CoA dehydrogenase) deficiency (see this term). Confirmation can only be obtained by measuring all three enzyme activities in cultured fibroblasts or by analysis of tissue biopsies. Prenatal diagnosis is available by measuring enzymatic activity in the chorionic villi (directly or cultured) or in cultured amniocytes. Molecular study of the genes coding for the alpha and beta subunits of MTP has led to the identification of numerous mutations.
Last update: March 2004
- Dr Christine VIANEY-SABAN