1. What Is MSUD?

MSUD, also known as Maple Syrup Urine Disease, is an Inborn Error of Metabolism caused by a defect in the enzyme needed to break down a specific group of amino acid called branched chain amino acids. The inability to completely metabolize these amino acids leads to a toxic build up of these and related acids in the body.

2. How And When Will We Know If My Baby Has MSUD?

If your baby’s newborn screening result showed a higher than normal leucine level, your child may have MSUD. The newborn screening test will be repeated and additional tests will be undertaken to help determine whether or not your baby has MSUD. The presence of alloisoleucine or genetic testing can also determine whether your baby has MSUD.

3. How Did My Baby Get This?

MSUD is an autosomal recessive genetic disorder. This means that if your baby has MSUD, he/she has two abnormal genes, one from the mother and one from the father. Each of you will have one mutated gene (a carrier). Being a carrier does not affect a person at all.

4. What Does It Mean For My Child?

If your baby has MSUD, he or she will have to be on a special protein restricted diet, and also take a special formula to ensure that the diet is adequate and balanced. Blood levels will be monitored and the diet adjusted throughout the lifespan, although most frequently during the early years. With proper care your child will be able to live a relatively normal and productive life. However, children with MSUD are at risk for intellectual and developmental disabilities. Special care must be taken during times of illness as the body will break down its own protein which can raise the level of leucine in the blood to dangerous levels. It is important to be vigilant and consider every illness seriously. 

5. What Is The Treatment? Does It Work? Is The Diet Too Difficult To Do?/Expensive?

MSUD is treated mostly through diet. A special medical formula and strict low protein diet will be prescribed by your doctor. Frequent monitoring of blood amino acid levels is required so the diet prescription can be adjusted as needed. A metabolic nutritionist will teach you how to follow the diet and prepare the formula as well as provide assistance in obtaining the formula through your health care provider or state agency.

6. What About My Other Children?/Future Children?

MSUD is an inherited condition. Children from the same father and mother as the affected infant have a 1 in 4 (25%) chance of having the same condition. Your metabolic doctor and/or pediatrician will advise you about whether siblings should be tested for MSUD.

It is important to let your obstetrician know that you have a child with MSUD if you are planning future pregnancies so that they can discuss testing options with you and prepare accordingly.