Complex I deficiency (z <−3SDs) was observed in patients carrying the m.3243A > G mutation (Patients 1, 3 and 5) and a patient carrying autosomal recessive POLG mutations (Patient 11), while decreased complex I levels (z <−2SDs) were observed in patients with m.3243A > G (Patient 4 and 6) and m.8344A > G (Patient 7) point mutations (Figure 3). Here, POLG is linked to hyperinsulinemic hypoglycemia, familial, 4.