The C2/(C16+C18:1) ratio is used as an index for diagnosing carnitine palmitoyltransferase-2 (CPT2) deficiency (OMIM 600650) and carnitine-acylcarnitine translocase (CACT) deficiency (OMIM 212138). Here, SLC25A20 is linked to hyperinsulinemic hypoglycemia, familial, 4.