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  • 06 May, 2020

  • 5 Min Read

Maple syrup urine disease (MSUD)

Maple syrup urine disease (MSUD)

Maple syrup urine disease (MSUD) is a rare genetic disorder characterized by deficiency of certain enzymes (branched-chain alpha-keto acid dehydrogenase complex) required to break down (metabolize) the three branched-chain amino acids (BCAAs) [Leucine, Isoleucine and Valine] in the body.

The result of this metabolic failure is that all three BCAAs, along with their various byproducts, accumulate abnormally throughout the body.

In the classic, severe form of MSUD, the plasma concentrations of the BCAAs begin to rise within a few hours of birth. If untreated, symptoms begin to emerge, often within the first 24-48 hours of life.

Symptoms of MSUD

The “non-specific” symptoms are those of increasing neurological dysfunction and include lethargy, irritability and poor feeding, followed soon by focal neurological signs such as abnormal movements and increasing spasticity, and shortly thereafter, by convulsions and deepening coma.

If untreated, progressive brain damage is inevitable and death ensues usually within weeks or months. The finding that is unique to MSUD is the emergence of a characteristic odor, reminiscent of maple syrup that can most readily be detected in the urine and earwax and may be smelled within a day or two of birth.

The disorder can be successfully managed through a specialized diet. However, even with treatment, both affected children and adults patients with MSUD remain at high risk for developing episodes of acute illness (metabolic crises) often triggered by infection, injury, failure to eat (fasting) or even by psychological stress. During these episodes there is a rapid, sudden spike in amino acid levels necessitating immediate medical intervention.

Types of MSUD

  1. classic MSUD
  2. intermediate MSUD
  3. intermittent MSUD
  4. thiamine-responsive MSUD

Source: TH

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