Biochemical testing included an acylcarnitine profile that demonstrated low carnitine free and total levels and elevations in long-chain acylcarnitine species including C16 and C18:1, suggestive of CPT II deficiency or carnitine-acylcarnitine translocase (CACT) deficiency. This evidence concerns the gene CPT2 and hyperinsulinemic hypoglycemia, familial, 4.