Panel Members: Drs. Hillman, Berry, Morton, Grange

Q. What causes the stomach cramps?
A. The formula is similar to predigested (highly concentrated) formula; it can cause irritation in the stomach and intestines, particularly when the formula is thick.

Q. Why are valine and isoleucine used when MSUD people are sick?
A. When there is a high leucine level, more of the other amino acids are required to make protein (use the excess leucine) to lower the leucine level. In addition, sufficient calories are necessary for protein synthesis. The amounts of additional valine and isoleucine vary depending on the patients, circumstances, etc. (A good assumption is to try to make the valine and isoleucine levels as close to normal as possible.)

Q. When leucine levels are elevated, where does the leucine go and what damage does it cause?
A. The leucine goes to the next metabolic step, forming the keto acids, which are present in the urine. Leucine inhibits phenylalanine in the brain. However, the keto acids are the primary poison. These acids interfere with growth, causing malnutrition. They also draw water into the cells.

Q. Why are there different management techniques (counting leucine vs. counting protein)?
A. Persons with MSUD can be normal when on well-controlled diets. However, if these same people are on poor diets, they will perform poorly. Children with leucine levels 5 to 10 mg./dl may behave like children with Attention Deficit Disorder. Dr. Morton feels that most problems experienced when levels are high can be reversed if the people are kept on well controlled diets. He likes to see leucine levels at 2 to 3 mg./ dl. People kept at 500-1000 micromols/Liter of leucine do not do as well as people under 500 (behavior is worse, etc.). In addition, persons with MSUD seem to have better recuperative abilities (such as from a coma) than most people.

Q. Does isoleucine keep leucine and valine stable?
A. All three are needed in the correct balance and available at the right time of protein synthesis to function correctly. However, leucine seems to be the only one that causes reactions. But you cannot regulate just leucine. All three must be balanced.

Q. Do all three amino acids cause ataxia?
A. If the valine is high, there are no symptoms. If isoleucine or leucine is high, ataxia will occur.

Q. Does it matter if a person with MSUD fasts or does not eat regularly?
A. Yes! Individuals with MSUD can go a normal time between meals, but it is important to regularly take in carbohydrates. The BCAAs have a lot to do with appetite control.


The MSUD Family Support Group is currently funding several research projects and we are proactively looking for researchers interested in developing new treatments or finding a cure for MSUD. Significant funding is necessary if we are to accomplish this goal.
Donate Today Learn More

Subscribe to our mailing list

Signup To Our E-Blast Signup with your email address to receive our e-blast newsletter.