What is MSUD?
Maple syrup urine disease (MSUD) is a rare but treatable inherited disorder that prevents the normal breakdown of protein.
Babies with MSUD inherit two faulty copies of the gene for MSUD, one from each parent.
When we eat, our body breaks down protein in food into smaller parts called amino acids. Special chemicals found naturally in our body, called enzymes, then make changes to the amino acids so our body can use them.
Babies with MSUD have problems breaking down three amino acids called leucine, isoleucine and valine because an enzyme is missing. This causes harmful substances to build up in their blood and urine. This can leave a sweet smell in the urine and sweat.
Babies with MSUD benefit significantly from early treatment and can live healthy and active lives.
Without early diagnosis and treatment they can develop serious illness and damage to the brain.
Symptoms of MSUD
Babies with MSUD are at risk of developing the following symptoms:
- poor feeding
- irritability
- sleepiness
- vomiting
- sweet smell in urine
- breathing difficulties and fast breathing
- coldness
These symptoms can be controlled with treatment. Left untreated, babies with MSUD can deteriorate, have fits and slip into a coma which can be life threatening.
This is due to high levels of the harmful substances in the body. If levels are very high, your baby might need intensive care and dialysis to bring down the levels as quickly as possible.
When babies with MSUD become ill, they might show symptoms of metabolic crisis. A metabolic crisis is a period of time when the effects of the condition make your child seriously ill. Some babies with MSUD might not develop symptoms of a metabolic crisis until later on in the first year of life or later in childhood. Causes of a metabolic crisis can include an infection such as a stomach upset or vomiting illness.
Treatment
Treatment for MSUD is based on a special low protein diet.
The aim of the diet is to reduce the build-up of leucine, isoleucine and valine which can cause metabolic crisis and learning difficulties. However, babies need a small amount of these amino acids to grow and develop. Your specialist metabolic dietitian will teach you how to measure and control the amount of protein you give to your baby, including breast milk feeds.
As high protein foods and milk (including breast milk and normal infant formula) have to be limited, a special infant formula which does not contain leucine, isoleucine and valine is given to meet all nutritional needs.
Your baby might also need supplements of isoleucine and valine to maintain blood levels at the right level. These supplements are very important because they allow normal growth and development and help to reduce the build-up of harmful toxins to the brain. Your baby will need regular blood tests to monitor the levels in their blood.