How is MSUD inherited?
MSUD is inherited in an autosomal recessive manner. It affects both boys and girls equally. In children with MSUD, a pair of genes needed to make the BCKAD enzymes is not working correctly. These children inherit one non-working gene for MSUD from each parent. Parents of children with MSUD rarely have the condition themselves. Instead, each parent has a single non-working gene for MSUD. They are called carriers. Carriers do not have MSUD because the other gene of this pair is working correctly. When both parents are carriers, there is a 25% chance in each pregnancy for the child to have MSUD. There is a 50% chance for the child to be a carrier, just like the parents. And, there is a 25% chance for the child to have two working genes.
