The rheumatologist suspected a metabolic myopathy and the patient underwent a metabolic myopathy panel, which showed elevated levels of hexadecanoylcarnitine (C16) and octadecanoylcarnitine (C18), a common finding in patients with CPT2 deficiency (Table 2) [4]. This evidence concerns the gene CPT2 and hyperinsulinemic hypoglycemia, familial, 4.