Curriculum · Metabolic and Endocrine and Diabetes Mellitus
Maple syrup urine disease
What it is
Maple syrup urine disease is an aminoacidopathy: a defect in the catabolic pathway of leucine, isoleucine and valine. Inheritance is autosomal recessive, and the defective enzyme is branched-chain alpha-keto acid dehydrogenase, or BCKD. The metabolites that accumulate are leucine, isoleucine, valine and the branched-chain keto acids.
How it presents
Severe symptoms come within the first days of life, typically after a few days, around day 7. The features are feeding difficulties, poor response and loss of reflexes, seizure with opisthotonos rigidity, and irregular respiration. Neurologic symptoms are severe, and there is lethargy, vomiting, coma and seizures. The urine smells sweet, like syrup; the maple syrup-like odor is due to the branched-chain keto acids.