Hi guys!
So, what is Maple Syrup Urine Disease(MSUD)?
-Leucine, isoleucine and valine can only be broken down by 6 proteins that make up a complex called BCKD (branched-chain alpha-ketoacid dehydrogenase)
-People with MSUD have a deficiency in one of the 6 proteins, and therefore can't break down those 3 amino acids
Why is it so serious?
-dangerously high levels of the 3 amino acids will accumulate in the blood, which causes rapid brain cells degeneration and can lead to death if untreated
How do people get MSUD?
-mutation in gene
-autosomal recessive
most common defect: alpha subunit in BCKD complex
caused by mutation in gene on chromosome 19 (BCKDHA gene)
Types of MSUD:
1) Classic MSUD ( Most common) - Symptoms of this type is normally detected within 4-7 days in newborn infants
- Symptoms include
- Poor feeding
- Vomiting
- Poor weight gain
- Increasing lethargy (difficult to wake up)
- Characteristic burned sugar smell to urine
- Changes in muscle tone, muscle spasms, and seizures
2) Intermittent MSUD
- 2nd most common
- 5% to 50% Branched-chain alpha ketoacid dehydrogenase
- Exhibits classic MSUD symptoms during infections or illnesses.
- Otherwise, infants can still develop normally
3) Intermediate MSUD
- Affected individuals will still have about 3% to 30% of branched-chain alpha ketoacid dehydrogenase
- Can appear well during the neonatal stage.
- So they can live a more normal life, but symptoms can still occur at any age.
4) Thiamine-responsive MSUD
- As the name suggests, Administering thiamine to the patient and a controlled diet will improve their condition.
- It is similar to intermediate MSUD
5) E3-deficient MSUD
- Rarest.
- Patients have additional deficient metabolic enzymes.
- Symptoms similar to that of intermediate MSUD but with severe lactic acidosis
Diagnosis:
- Newborns are normally screened for MSUD in screening programs.
- It is detected based on physical symptoms, clinical features and by decreased levels of BCKAD enzyme activity causing accumulation of BCAAs, allo-isoleucine, and branched-chain ketoacids (BCKAs) in tissues and plasma.
- Blood test for amino acid levels for those with family history of MSUD.
Treatment:
- Life long low protein diet
- Thiamine for those with thiamine-responsive MSUD
Symptoms:
-loss of appetite
-fussiness
-urine that smells like maple syrup
If left untreated, condition worsen:
-seizures
-go into coma
-death
References:
http://rarediseases.about.com/od/rarediseases1/a/062004.htm
http://flipper.diff.org/app/items/info/4499
http://themedicalbiochemistrypage.org/msud.html
http://learn.genetics.utah.edu/content/disorders/whataregd/msud/
Hi everyone
We will be doing a study on maple syrup urine disease! Stay tuned for more posts! :D