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Mucopolysaccharidosis type IVB/ GM1 gangliosidosis

Mucopolysaccharidosis type IVB (MPS IVB), also known as Morquio B syndrome, causes difficulty breaking down certain sugar molecules. This affects bone development. Symptoms of the condition usually begin in early childhood and may include short stature and problems with the formation of the knees, ribs, spine, hips and wrists. Sometimes, individuals with this condition have progressive vision loss and develop a coarseness of facial features; typically intelligence is not affected. Morquio B syndrome is a life limiting condition.

Changes in this gene can also cause a condition called GM1 gangliosidosis. Babies affected by GM1 gangliosidosis appear normal at birth however begin to lose skills within the first 6 months of life. Symptoms include problems with bone development, intellectual disability, vision loss and a bigger than normal liver and spleen. Sadly, babies who present early are most severely affected and die within the first few years of life.

Quick facts about mucopolysaccharidosis type IVB/ GM1 gangliosidosis
Genes: GLB1
Inheritance: Autosomal Recessive
Alternative Names: Morquio B syndrome, GM1 gangliosidosis, Mucopolysaccharidosis typ IVB, MPS IVB
Relevant resources for mucopolysaccharidosis type IVB/ GM1 gangliosidosis

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 mucopolysaccharidosis type IVB/ GM1 gangliosidosis inherited?

mucopolysaccharidosis type IVB/ GM1 gangliosidosis 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 condition.

If both parents are carriers of mucopolysaccharidosis type IVB/ GM1 gangliosidosis, there's a one in four chance that their children could develop symptoms.

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 condition in your child. Eugene offers an inclusive genetic carrier screening panel that includes mucopolysaccharidosis type IVB/ GM1 gangliosidosis, 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 mucopolysaccharidosis type IVB/ GM1 gangliosidosis before or early in pregnancy?

The biggest benefit of screening for mucopolysaccharidosis type IVB/ GM1 gangliosidosis 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 condition is low.

Since 90% of children that have a recessive genetic condition like mucopolysaccharidosis type IVB/ GM1 gangliosidosis 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 condition in the first place.