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Usher syndrome type ID

Usher syndrome is a condition that affects hearing and vision, and sometimes balance. There are several types of Usher syndrome, caused by variations in different genes. Usher syndrome type ID (USHID) is caused by variations in the CDH23 gene.

Children affected by USHID are usually born with severe to profound hearing loss. The degree of hearing loss may become worse over time. Progressive vision loss, due to a condition known as retinitis pigmentosa (RP), usually begins in childhood. USHID is also associated with poor balance due to problems with the inner ear. This in turn can cause a delay in meeting milestones, such as sitting and walking in infancy.

The severity of symptoms can vary, even amongst individuals of the same family. Intelligence and life expectancy are not typically affected. Early initiation of medical, educational, and social services is recommended for affected individuals to maximize outcomes.

Quick facts about Usher syndrome type ID
Genes: CDH23
Inheritance: Autosomal Recessive
Relevant resources for Usher syndrome type ID

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 ID inherited?

Usher syndrome type ID 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 ID, 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 disease in your child. Eugene offers an inclusive genetic carrier screening panel that includes Usher syndrome type ID, 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 ID before or early in pregnancy?

The biggest benefit of screening for Usher syndrome type ID 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 ID 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.