NIH

Zebra of the Week: Maple syrup urine disease

November 5, 2024

Maple syrup urine disease (MSUD) occurs when the body is unable to breakdown certain parts of proteins, which leads to the build-up of toxic substances that can cause organ and brain damage. There are several forms of MSUD, with classic or infantile being the most common.

Symptoms of the classic form of MSUD start in early infancy and include poor feeding, irritability, hypersomnolence, and muscle spasms. The cerumen and urine of infants with MSUD smells like maple syrup. Symptoms of other forms of MSUD start in adolescence or adulthood.

MSUD is caused by genetic variants in the BCKDHA, BCKDHB, or DBT genes. It's inherited in an autosomal recessive pattern. Diagnosis of MSUD is based on the symptoms, clinical exam, and blood and urine testing. MSUD is often diagnosed based on the results of a newborn screening test.

Source:

NIH. Genetic and Rare Diseases Information Center. Maple syrup urine disease. https://rarediseases.info.nih.gov/diseases/3228/maple-syrup-urine-disease