Abstract
Isolated methylmalonic acidemia (MMA) is a rare, genetically heterogeneous group of metabolic disorders resulting from a deficiency of the enzyme methylmalonyl-CoA mutase (MMUT), defects in the metabolism of its cofactor, adenosylcobalamin, or deficiency of the enzyme methylmalonyl-CoA epimerase. With improved awareness, earlier diagnosis, and advances in care, women with MMA are increasingly reaching childbearing age, and successful pregnancies have been documented in patients with milder forms of the disease. This report details, for the first time, the management and outcomes of pregnancy in a woman with severe mut(0) deficiency and concomitant advanced chronic kidney disease (CKD) progressing to end-stage renal disease (ESRD) requiring initiation of hemodialysis at 21 weeks' gestation. At 20 weeks, fetal ultrasound revealed fetal growth restriction (FGR), necessitating close monitoring and dietary adjustments to meet the patient's increased nutritional needs. Despite these challenges, she remained metabolically stable until delivery. At 35 weeks, she delivered a 1.64 kg male SGA newborn via cesarean section. The newborn presented with mild retrognathia, a soft palate cleft, mild hypospadias, mild ventriculomegaly, and hypoplasia of the corpus callosum and cerebellum without the need for immediate intervention. The mother experienced a mild metabolic decompensation on the fifth postpartum day, which was promptly managed by additional renal replacement therapy. At 3 months postpartum, both mother and child were doing well, with no further metabolic complications observed. This case report demonstrates that pregnancy in patients with severe mut(0) deficiency is challenging and requires a close interdisciplinary management but can be carried out with a favorable outcome.