New Mitochondrial Disease Identified In Monozygotic Twin Boys

who had been diagnosed at 5 months, started on treatment, and died at 29 months. A second pregnancy with an affected fetus was electively terminated, and another sibling was diagnosed prenatally, received palliative care after birth, and succumbed to the disease at 8 months of age. For this trial, the fetus was treated with alglucosidase alfa (at 20 mg per kilogram of estimated fetal weight) administered under ultrasonic guidance through the umbilical vein beginning at 24 weeks, 5 days of gestation. Treatment was continued at 2-week intervals through 34 weeks, 5 days of gestation. At each infusion, plasma trough levels of GAA enzyme activity and serum antidrug antibody titers were measured. After birth, the infant received immune tolerance induction on day 1 and day 4. Then, every other week, she received another infusion of ERT. This protocol is consistent with standard-of-care treatment for CRIM-negative infantileonset Pompe’s disease. The infant was subsequently transitioned to a higher dose (40 mg per kilogram) given every 2 weeks at 9.6 months of age and then a weekly dose of 40 mg per kilogram at 11.3 months of age. No adverse reactions to any of the six infusions were observed at any point. At 13 months of age, the child showed no signs of cardiovascular complications or motor deficits, and normal creatine kinase levels were present.