Treatment involved dietary restriction of the amino acids leucine, isoleucine, and
valine. This treatment must begin very early to prevent brain damage. Babies
Maple Syrup Urine Disease (MSUD)
What is maple syrup urine disease (MSUD)?
MSUD is a potentially deadly disorder that aᄳ失ects the way the body breaks down three amino acids: leucine, isoleucine, and
valine. When they're not being used to build a protein, these three amino acids can either be recycled or broken down for
energy. They are normally broken down by six proteins working together as a complex called BCKD (branched-chain alphaketoacid
dehydrogenase).
People with MSUD have a mutation that renders one of the 6 proteins in the complex de삀cient. Therefore, they can't break
down leucine, isoleucine, and valine. They end up with dangerously high levels of these amino acids in their blood, causing the
rapid degeneration of brain cells and, if left untreated, even death.
Defects in any of the six subunits of the BCKD protein complex can cause MSUD. The most common defect is caused by a mutation in a gene on
chromosome 19 that encodes the alpha subunit of the BCKD complex (BCKDHA).
How do people get MSUD?
What are the symptoms of MSUD?
How is MSUD treated?
6/17/2016 Maple Syrup Urine Disease (MSUD)
http://learn.genetics.utah.edu/content/disorders/singlegene/msud/ 2/2
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with the disease must eat a special formula that does not contain the amino
acids leucine, isoleucine, and valine. As the person grows to adulthood, he or
she must always watch their diet, avoiding high-protein foods such as meat,
eggs, and nuts.
If levels of the three amino acids still get too high, patients can be treated with
an intravenous (given through a vein) solution that helps the body use up excess
leucine, isoleucine, and valine for protein synthesis.
Gene therapy is also a potential future treatment for patients with MSUD. This
treatmentwould involve replacing the mutated gene with a good copy, allowing
the patient's cells to make a functional BCKD protein complex and break down
the excess amino acids.