The management and long term outcome of organic acidaemias.

We review the outcome of patients with maple syrup urine disease (14 classical patients and three variants), biotinidase deficiency (two patients) and non-cofactor-responsive variants of methylmalonic acidaemia (eight patients), propionic acidaemia (eight patients) and isolated 3-methylcrotonyl CoA carboxylase deficiency (three patients). Their survival, growth, intellectual development and other clinical problems are analysed. With the exception of isolated 3-methylcrotonyl CoA carboxylase deficiency the outcome of patients with disorders that are not cofactor responsive is disappointing. Twelve patients have died (five maple syrup urine disease, two methylmalonic acidaemia, five propionic acidaemia) and many of the survivors are developmentally retarded. The outlook is worst for patients with propionic acidaemia presenting in the neonatal period but a good outcome is possible for patients with maple syrup urine disease if the diagnosis is made early.