This ratio has been used to improve the diagnostic specificity for carnitine-acylcarnitine translocase (CACT) deficiency and carnitine palmitoyl transferase 2 (CPT2) deficiency, which were regarded as inherited disorders of mitochondrial long-chain fatty acid oxidation [46]. This evidence concerns the gene SLC25A20 and hyperinsulinemic hypoglycemia, familial, 4.