[Onset of hereditary metabolic encephalopathy can be seen after the neonatal period]

Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder causing accumulation of the branched amino acids valin, isoleucin, leucin and their toxic metabolites resulting in ketoacidosis, progressive neurological deterioration and cerebral oedema. The classical form presents in the first days of life. In contrast, the intermittent form of MSUD presents later in childhood and is difficult to diagnose biochemically. Clinical awareness is important due to high mortality if not treated. We here present two cases with late-onset intermittent MSUD.