For the purpose of this discussion post, I will be discussing the hereditary metabolic disorder
known as Maple Syrup Urine Disease.
Maple Syrup Urine Disease (MSUD) is caused by a body's inability to metabolise and break
down three amino acids known as leucine, isoleucine, and valine (NHS website, 2021). This
disease can be deadly if it is left untreated because the body is not able to break down the
amino acids, and then those unbroken amino acids remain in the body and will eventually
eventually death (Cleveland Clinic, 2019).
This disease is caused by a deficiency in the enzyme known as branched-chain alpha-keto
acid dehydrogenase which is necessary for the breaking down of the branch chain amino
acids leucine, isoleucine, and valine (NORD - National Organization for Rare Disorders,
2020).
The most common symptoms for MSUD can include:
A sweet-smelling urine and sweat, for which it gets its name
Decreased feeding
. Lethargy Changes in muscle tones
Abnormal movements
Developmental delay
Seizures, convulsions, respiratory failure, coma, and death.
These symptoms are the result of the inability to break down the amino acids. I have not
found a source that explains why there is a sweet smell, it could be the toxin build up that
releases a sweet smell, or it could be the nutrients that are metabolised that give off a sweet
smell. I would guess it is the former. The lethargy, lack of muscle tone, and decreased feeding
could be the result of a lower than needed level of energy. Since proteins result in muscle
creation, the inability to break down proteins will result in lower muscle development (NHS
website, 2021). The lethargy could be due toxin build up or a lack of nutrients from protein.
The more serious symptoms like seizures, convulsions, coma, and death are the result of the
toxin build up (NHS website, 2021).
The treatment for this disease is life-long. The most common treatment is a strict diet which
severely limits the intakes of the proteins that cannot be broken down (NHS website, 2021)
Other treatment can include injections of the proteins that can be broken down (NORD -
National Organization for Rare Disorders, 2020). These treatments do not actually treat the
disease, instead they make it possible to live a long life with the disease (NORD - National
Organization for Rare Disorders, 2020).
There is the option of a liver transplant which will then be able to produce the enzymes
needed for the breaking down of the BCAA's leucine, isoleucine, and valine (NORD -
National Organization for Rare Disorders, 2020). This treatment is unlikely since it is
difficult to find donor livers. This will however be a more permanent fix if the liver is
accepted into the body (NORD - National Organization for Rare Disorders, 2020)
References
Cleveland Clinic. (2019, November 18). Maple Syrup Urine Disease (MSUD). Retrieved September
13, 2022, from https://my.clevelandclinic.org/health/diseases/21168-maple-syrup-urine-
disease#:%7E:text=Because%20people%20with%20MSUD%20can,and%20physical
%20disabilities%20and%20death.
NHS website. (2021, November 18). Maple syrup urine disease. nhs.uk. Retrieved September 13,
2022, fromhttps://www.nhs.uk/conditions/maple-syrup-urine-disease/#:%7E:text=Maple
%20syrup%20urine%20disease%20(MSUD,and%20fish%20into%20amino%20acids
NORD - Nation