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Maple Syrup Urine Disease Case Study

Philip Kendall

MSUD Case Study

Maple Syrup Urine Disease(MSUD) is an autosomal recessive disease.  Its name is derived from the smell of the urine of the affected infant. Left untreated, the disease causes mental retardation, growth retardation, and eventual death. MSUD is caused by a mutation in the protein complex branch-chained ketoacid dehydrogenase (BCKD). This protein complex handles the digestion of amino acids leucine, isoleucine, and valine. Since they cannot be digested, they build up in the body causing brain swelling and other syptoms. To treat this disease, the patient’s diet is strictly limited to exclude those amino acids, and in certain cases a liver transplant has been done.

In this case study, a couple’s child is diagnosed with MSUD. There had been no problems through pregnancy and birth, but once Matthew was born, he had failed to thrive. He was brought to the doctor who diagnosed him with MSUD. Matthew was placed on a strict low protein diet. Despite this diet, he still suffered from chronic and severe metabolic crises.

The family’s only option for making their son better was getting a liver transplant. There was a 40% chance that Matthew’s body would reject the liver even if he survived the surgery. There must be better ways to treat the disease? What about supplementation of the BCKD protein complex to allow the body to digest the built up amino acids? I understand that a liver transplant could be more effective because then the body is able to synthesize its own enzyme rather than the patient relying on getting regular supplements. I feel that the option of BCKD supplementation in conjunction with dietary regulation should be considered over a liver transplant.

There must be ways to screen for this disease as well. A homozygous dominant individual should have normal amino acid blood levels because they have to functional alleles in their genome. A homozygous recessive individual is affected by MSUD and will have high amio acid blood levels because they lack a functional allele to produce proper proteins. Heterozygous carriers are not affected by MSUD, but only have one functional allele. Since they only have one functional allele, their amino acid blood levels should be higher than homozygous dominant individuals.

 

http://learn.genetics.utah.edu/content/disorders/singlegene/msud/

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