MSUD is a recessive genetic disease. This means both parents of a child with MSUD must carry a mutation in the same gene (the same genetic code). These mutated genes do not function normally, thus causing disease. A person with a gene mutation is called a carrier. Carriers are not affected by their one abnormal gene. (Just as everyone carries genetic codes for things like the color of hair and eyes, everyone also carries several abnormal genes which can cause disease.)

Each individual person has two genes that code for the enzyme activity involved in the breakdown of the BCAAs-one gene coming from the father and one from the mother. If one gene functions normally, but the other does not, then the person is a carrier of MSUD. If neither gene functions normally, then that person has MSUD. It is also possible to receive the normal gene from each parent and not have any mutated genes for the disease.

When parents are both carriers of the gene for MSUD, with each pregnancy, there is a 1 in 4 chance of having a baby with MSUD, a 2 in 4 chance that the baby will have only one gene for MSUD and be a carrier like the parents, and a 1 in 4 chance that the baby will neither be a carrier nor have MSUD.

Volume 35-1
23 April 2017

A Message from the Editor

Volume 35-1
23 April 2017



A Child's Life

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