Successful pregnancy in severe methylmalonic acidaemia

Methylmalonic acidaemia is an inborn error of metabolism characterized by recurrent episodes of life-threatening ketoacidosis. With improved and intensive treatment, these patients are living into adulthood, but many experience late-onset disease complications such as chronic renal failure, chronic pancreatitis and osteopenia. We report the successful delivery of a healthy baby to a 20-year-old woman with vitamin B₁₂-unresponsive methylmalonic acidaemia who has these late-onset manifestations of the disease and had plasma methylmalonic acid concentrations of 1900 μmol/L during the first trimester of pregnancy.