Maple Syrup Urine Disease

Question 1

What enzyme group is deficient in maple syrup urine disease?

Answer 1

Branched chain keto-acid dehydrogenase

Question 2

What amino acids are broken down by branched chain keto-acid dehydrogenases? Which aa is the most toxic?

Answer 2

leucine (most toxic)
isoleucine
valine

Question 3

How is maple syrup urine disease inherited?

Answer 3

Autosomal Recessive

Question 4

Name 3 types of presentation of Maple Syrup Urine disease

Answer 4

1. Severe neonatal form (classical 75%)
2. Acute-intermittent, late onset form
3. Chronic progressive form

Question 5

What features do neonates with severe neonatal MSU disease have?

Answer 5

Normal pregnancy/delivery
Poor feeding
Drowsiness which progresses into coma +/- cerebral edema
Neurovegetative dysregulation ketosis
Have a sweet/malty/caramel maple syrup odour
NO ACIDOSIS

Question 6

What features do children with acute-intermittent, late onset MSU disease have? When do these episodes usually start?

Answer 6

1/3 appear in the first year of life.
Recurrent attacks of coma/lethargy/ataxia, hypoglycemia, chronic vomiting and failure to thrive, selective anorexia, progressive developmental delay

Question 7

Name 2 ways that the chronic progressive form of Maple Syrup Urine disease can present?

Answer 7

1. Digestive presentation- anorexia, vomiting, FTT

2. Neurologic presentation- Hypotonia, developmental delay, weakness, seizures

Question 8

How do you diagnose Maple Syrup Urine disease?

Answer 8

Plasma amino acid levels
Enzymatic studies
Molecular analysis

Question 9

How do you treat maple syrup urine disease? (5 methods)

Answer 9

1. Restrict leucine, isoleucine and valine intake.
2. Receive an aa mixture without these
3. In an emergency leucine can be removed with exchange transfusion or hemodialysis
4. Some responsive to thiamine
5. Avoid situations that promote protein catabolism! Infections, vaccines, trauma.

Question 10

What is the prognosis of Maple Syrup urine disease?

Answer 10

Some individuals may have some degree on intellectual disability, depends on early recognition