Analysis of fatty acid oxidation intermediates in cultured fibroblasts to detect mitochondrial oxidation disorders.

We describe a method for the diagnosis of mitochondrial fatty acid oxidation disorders that is based on the analysis of acylcarnitine and acyl-coenzyme A (acyl-CoA) esters generated during fatty acid oxidation by permeabilized skin fibroblasts. This method requires only small amounts of cultured fibroblasts with minimal preparation, and no isolation of mitochondrial fractions is necessary. During oxidation of [U-14C]hexadecanoate, normal human fibroblasts from patients with fatty acid oxidation defects show a completely different pattern of intermediates, and in each case the observed profile reflects the site of the defect. The diagnosis and likely site of a mitochondrial fatty acid oxidation defect can be made readily from two 80-cm2 culture flasks of fibroblasts with this technique.