Considerations for Prenatal and Postpartum Management of a Female Patient with Ornithine Transcarbamylase Deficiency

We report on pregnancy management and outcomes in a 27-year-old female patient with ornithine transcarbamylase (OTC) deficiency, the most common inherited enzyme deficiency in the urea cycle. Our patient was diagnosed during childhood after hyperammonemia associated with surgery and steroid treatment and was well-controlled with nitrogen scavenger treatment, low-protein diet, and L-citrulline supplementation. OTC gene sequencing identified a variant of unknown significance that has more recently been classified as likely pathogenic. Women with OTC deficiency are at increased risk of hyperammonemia during pregnancy and the postpartum period, therefore monthly follow up and laboratory assessments are critical in management decision making. Our patient was maintained on glycerol phenylbutyrate, L-citrulline and essential amino acid supplements, along with restricted protein intake during pregnancy. A multidisciplinary approach with the obstetrics, prenatal genetics, high risk obstetric, and anesthesia teams was also necessary for optimal management during pregnancy, throughout labor and delivery, and during the postpartum period. After successful childbirth and discharge, our patient experienced a hyperammonemic crisis related to poor enteral nutrition, and acute management protocols were implemented to stabilize her. For her newborn son, acute hyperammonemia protocols were on standby, and newborn screening and laboratory testing were expedited to assess his risk. He was healthy and did not experience symptoms of concern. In this case report, we emphasize the importance of close collaboration with maternal-fetal medicine team members during and immediately after pregnancy to ensure successful management of a female patient with OTC deficiency and her newborn.