Usher syndrome type IIIA

Usher syndrome type IIA is a genetic condition that affects hearing and vision. Most people are born with mild to severe hearing loss that mainly affects their ability to hear high-frequency sounds. The degree of hearing loss may become worse over time. The degree of hearing loss also varies within and among families with this condition, and it may become worse over time.

The vision loss experienced by individuals affected with Usher syndrome type IIIA is progressive and usually begins in late childhood or adolescence. This condition is known as retinitis pigmentosa (RP). The hearing loss experienced by people with this form of Usher symdrome usually becomes profound by middle age. Balance problems are also common later in life.

Quick facts about Usher syndrome type IIIA
Genes: CLRN1
Inheritance: Autosomal Recessive
Alternative Names: Usher syndrome
Relevant resources for Usher syndrome type IIIA

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 Usher syndrome type IIIA inherited?

Usher syndrome type IIIA 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 Usher syndrome type IIIA, 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 Usher syndrome type IIIA, 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 Usher syndrome type IIIA before or early in pregnancy?

The biggest benefit of screening for Usher syndrome type IIIA 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 Usher syndrome type IIIA 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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