At baseline, median Hb concentration was 9.2 mmol/L (IQR 8.7–9.9) for patients with normal ITPase activity and 9.3 mmol/L (IQR 8.7–9.9) for patients with ITPase deficiency (p = 0.793). Here, GSTM1 is linked to hyperinsulinemic hypoglycemia, familial, 4.