Maple syrup urine disease (MSUD) type 1B

Maple syrup urine disease (MSUD) affects how the body turns food into energy. It gets its name from the sweet smell of the urine in young children with the disease.

MSUD is a variable disease, which is differentiated based on how serious the symptoms are and the age of onset. The most common and serious form of MSUD often begins shortly after birth. Symptoms can include problems with feeding, vomiting, low energy levels, problems with movement and delayed development. Milder forms of MSUD can begin later in childhood and cause delayed development and other problems if they are not treated appropriately.

Keeping to a protein restricted diet, high calorie supplementation and other treatment options can help manage MSUD, reverse symptoms and improve health and quality of life. Unfortunately, if left untreated this condition can cause early death.

Quick facts about maple syrup urine disease (MSUD) type 1B
Genes: BCKDHB
Inheritance: Autosomal Recessive
Relevant resources for maple syrup urine disease (MSUD) type 1B

A quick genetics rundown

As humans we have about 23,000 genes. These genes are like tiny instruction manuals that influence our health, growth and development. We inherit half of our genes from our biological mum and the other half from our biological dad. These genes are lined up on structures called chromosomes. Most of us have 23 pairs of chromosomes. The first 22 pairs are called autosomes and for the most part - these are the same among men and women. The 23rd pair determine our sex - two X chromosomes for a female and one X and one Y chromosome for males.

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How is maple syrup urine disease (MSUD) type 1B inherited?

maple syrup urine disease (MSUD) type 1B is known as an autosomal recessive condition. For autosomal recessive conditions, if a person has a variation in one copy of their gene, they are a carrier. This means that they are healthy because they also have a working copy of the gene. But, they can still pass their non-working copy to their child.

If the other parent also happens to be a carrier of the same gene, there is a 25% (1 in 4) chance that they both pass this gene variation on to their child — and as such, have a child affected by the disease.

If both parents are carriers of maple syrup urine disease (MSUD) type 1B, there’s a one in four chance that their children could develop symptoms.
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What is carrier screening?

Carrier testing is like a checkup for your genes. It tests to see if you carry a gene variation that could cause a serious genetic disease in your child. Eugene offers an inclusive genetic carrier screening panel that includes maple syrup urine disease (MSUD) type 1B, but there's a total 301 conditions that can be tested.

Eugene’s carrier test is a clinical grade test that can be done from the comfort of your own home — it’s just a saliva test. You're also paired with a genetic counsellor who provides mindful support and guidance every step of the way.

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Should parents screen for maple syrup urine disease (MSUD) type 1B before or early in pregnancy?

The biggest benefit of screening for maple syrup urine disease (MSUD) type 1B is that it can help future parents understand their reproductive risk so they can be ready and empowered to make more informed decisions. If neither partner are carriers, it provides reassurance and peace of mind that the risk of having a child with a genetic disease is low.

Since 90% of children that have a recessive genetic disease like maple syrup urine disease (MSUD) type 1B had no previous family history of it, it often feels completely out of the blue for the parents. Getting screened is a way to know this risk in advance, which can help familes manage or even prevent the disease in the first place.

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