The core management of MSUD is a special “medical food” or formula. This formula provides all the nutrients a child needs except three specific amino acids—leucine, isoleucine, and valine—that the body cannot process properly. These amino acids are added in precise amounts based on regular monitoring of the child’s growth and blood levels.
Foods that contain protein are very limited. This carefully managed diet gives the child enough protein to grow and develop while preventing harmful buildup of amino acids in the blood. Lifelong monitoring and close medical supervision are essential. Illness, stress, or eating too much protein from regular food can raise amino acid levels and their toxic byproducts in the blood. Even a mild illness can become dangerous if amino acid levels cannot be regulated. During these times, doctors may recommend diet changes, more frequent analysis of amino acid and keto acid levels in the blood and urine, or hospitalization to manage MSUD.
Branched-chain amino acids are processed in tissues throughout the body, including muscles and organs, but the liver plays a major role in breaking down the amino acids affected by MSUD. Because of this, a liver transplant can be a treatment option. A healthy donor liver provides enough enzyme activity to allow a person with MSUD to eat a normal diet and avoid metabolic crises during illness. In rare cases, elevated amino acid levels have been seen in some transplanted individuals during illness.
It’s important to know that a transplant does not remove the abnormal gene. A person born with MSUD will still carry the gene and can pass it on to their children.
Chief, Pediatric Transplantation, Professor of Surgery and Critical Care,
University of Pittsburgh School of Medicine