Incomplete development of the brain in a newborn with methylmalonic aciduria.

The investigation of the brain from a seven-day-old girl who died from a disorder in the metabolism of methylmalonic acid revealed a severe reactive gliosis of the cerebral white matter and the deeper layers of the cortex, incomplete development of the fetal granular layer of the cerebellum and the Bergmann glial cells, and delayed myelination of the cerebellum, the brainstem, and the cervical spinal cord. We suggest that some of the described neuropathological findings are an immediate consequence of a disturbed methylmalonic acid metabolism starting in utero, and not exclusively a secondary phenomenon due to accumulation of metabolites and acidosis postpartum.