CPT2 and hyperinsulinemic hypoglycemia, familial, 4: CPT1 deficiency (CPT1D), CPT2 deficiency (CPT2D), and CACT deficiency (CACTD) are rare autosomal inherited recessive disorders, and the causative genes are CPT1A, CPT2, and SLC25A20, respectively (Wieser et al., 2003; Collins et al., 2010; Indiveri et al., 2011).