Molecular and enzymatic characterization of a unique carnitine palmitoyltransferase 1A mutation in the Hutterite community

Hepatic carnitine palmitoyltransferase 1 (CPT1A) deficiency is a rare disor der of mitochondrial fatty acid oxidation inherited as an autosomal recessi ve trait. Symptomatology comprises attacks of hypoketotic hypoglycemia with risk of sudden death or neurological sequelae, Only one CPT1A mutation has been reported so far. Identification of the disease-causing mutations allo ws both insights into the structure-function relationships of CPT1A and man agement of the patients and their relatives, The molecular analysis of CPT1 A deficiency in a large Hutterite kindred illustrates this point. Both cDNA and genomic DNA analysis demonstrate that the affected patients are homozy gous for a 2129G>A mutation predicting a G710E substitution, Studies in fib roblasts from one patient as well as heterologous expression of the mutagen ized CPT1A in yeast show that the G710E mutation alters neither mitochondri al targeting nor stability of the CPT1A protein. By con contrast, kinetic s tudies conclusively establish that the mutant CPT1A is totally inactive, in dicating that the G710E mutation dramatically impairs the catalytic functio n of CPT1A. Finally, due to a strongly suspected founder effect for the ori gin of CPT1A deficiency in this Hutterite kindred, identification of this d isease-causing mutation allows the setup of a targeted DNA-based newborn sc reening in this at-risk population, (C) 2001 Academic Press.