ERT on newborn Morquio A tolerant mice (8 weeks with 250 U/g of E6-GALNS). Untreated mice showed numerous vacuoles in (A) liver, (C) heart valves, (E) bone marrow, and (G) chondrocytes in femur growth plates. After 8-weekly intravenous injection of E6-GALNS, reduction of storage materials was observed in (B) liver, (D) heart valves, (F) bone marrow, and (H) cartilage cell layer. ERT, enzyme-replacement therapy; GALNS, N-acetylgalactosamine-6-sulfate sulfatase.