Maple syrup urine disease

What is Maple syrup urine disease?

A rare inherited disorder of branched-chain amino acid metabolism classically characterized by poor feeding, lethargy, vomiting and a maple syrup odor in the cerumen (and later in urine) noted soon after birth, followed by progressive encephalopathy and central respiratory failure if untreated. The four overlapping phenotypic subtypes are: classic, intermediate, intermittent and thiamine-responsive MSUD.

Other condition names

  • BCKD deficiency
  • BCKDH deficiency
  • Branched-chain 2-ketoacid dehydrogenase deficiency
  • Branched-chain ketoaciduria
  • MSUD

Inheritance type

Autosomal recessive


  • Europe: 1-9 in 1,000 000

Age of Onset

  • Childhood
  • Infancy
  • Neonatal
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