Objective: To evaluate prenatal treatment with hydroxycobalamin (OH-Cbl) in a pregnancy at risk for a severe form of the cobalamin C defect and postnatal treatment of the affected child.
Study design: Observational study with non-randomized intervention.
Results: In contrast to reported pregnancies with affected fetuses in which maternal methylmalonic aciduria was found in the last trimester of pregnancy, there was no maternal methylmalonic aciduria in our case, given prenatal treatment with intramuscular OH-Cbl. We did not find that the concentration of odd long-chain fatty acids in cord blood erythrocytes reflects fetal methylmalonic academia. After birth, the infant was treated with intramuscular OH-Cbl and oral carnitine. Oral folate and betaine were added as adjunct therapy to decrease plasma total homocysteine. Because of inadequate metabolic control, a diet reduced in natural protein was introduced. The child had normal developmental milestones but had nystagmus, hyperpigmented retinopathy, and discrete truncal muscular hypotonia.
Conclusions: Despite prenatal and postnatal treatment, adequate metabolic control, absence of metabolic crises, and normal developmental milestones, this patient with the cobalamin C defect had characteristic symptoms of the disease.