What is MSUD?
MSUD is an inherited condition in which the body cannot break down leucine, isoleucine and valine, three amino acids found in protein.
Every meal that contains protein adds these amino acids to the blood. Without treatment, they build up and cause swelling in the brain in the first days of life.
- Protein in a mealEvery meal adds leucine, isoleucine and valine.
- Three amino acids build upThe body cannot break them down.
- Swelling in the brainWithout treatment, in the first days of life.
How is MSUD found?
A newborn screen can catch MSUD at birth.
Finding it early matters, because without treatment the amino acids begin to build up within the first days of life.
How is MSUD treated today?
MSUD is treated today with a strict, measured low-protein diet for life, with medical formula replacing most food, and regular blood tests.
Any illness or missed meal can tip the balance, and families learn to go to the hospital early and often.
A liver transplant can free the diet, but it is major surgery, needs lifelong anti-rejection medication, and a transplanted liver can fail.
What could gene therapy change?
Gene therapy aims to give the body a working copy of the missing gene, so the child's own liver can process protein.
The goal is one treatment early in life in place of a diet or a transplant. The research is early.
Today
- A strict, measured low-protein diet for life
- Medical formula replacing most food
- Regular blood tests
- Hospital visits early and often with any illness
- Or a liver transplant, with lifelong anti-rejection medication
The goal
- A working copy of the missing gene
- The child's own liver processes protein
- One treatment, early in life
- In place of a diet or a transplant
Where does MSUD occur?
MSUD occurs worldwide, and it is most common in the Old Order Mennonite community in Lancaster County, Pennsylvania, at about 1 in 400 live births.
| Where | How often |
|---|---|
| Old Order Mennonite community, Lancaster County, PA (the highest known rate in the world) | About 1 in 400 live births |
| General population | About 1 in 200,000 |
| Parts of Brazil, Portugal, Turkey and the Philippines | Higher than average |
Sources: UMass Chan Medical School, 2025 to 2026.
How does Harvest of Compassion help?
Harvest of Compassion funds early research first, and treatment access for families second.
You can give to support the research, and clinics and programs can request funding.
This page is general information, not medical advice. Talk to your child's care team about treatment.
Follow the harvest
One email when something moves: a project funded, a research step completed, a date families should know. No more than once a month.