XRCC6P5 and hyperinsulinemic hypoglycemia, familial, 4: We next examined whether AA impaired DNA repair by evaluating the levels of predominant DNA repair proteins, including excision repair cross-complement rodent repair deficiency, complementation group 1 and 2 (ERCC1 and ERCC2), methylguanine methyl transferase (Mgmt) and Poly [ADP-ribose] polymerase 1 (PARP1).