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Alport syndrome, X-linked (COL4A5-related)

X-linked Alport syndrome (XLAS) is a disorder that causes kidney, hearing, and eye problems. XLAS is caused by changes in the COL4A5 gene. People who are affected by XLAS usually present with symptoms of kidney disease and hearing loss in late childhood or teens. The symptoms of kidney disease progresses from blood and protein in the urine to end-stage renal disease in the 30s and 40s. Changes in the tissues of the eye usually begin to appear in the 20s and 30s, however, these changes do not cause loss of vision. Intellect is not usually impacted. People within the same family can be affected in different ways.

Males with XLAS typically have symptoms that start earlier and are more severe than symtoms in carrier females. Female carriers typically have hematuria, though some may develop more severe kidney disease and other symptoms of the disorder.

Treatment is focused on managing the individual's symptoms; often, kidney transplant will be required, especially for males.

Quick facts about Alport syndrome, X-linked (COL4A5-related)
Genes: COL4A5
Inheritance: X-linked
Relevant resources for Alport syndrome, X-linked (COL4A5-related)

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 Alport syndrome, X-linked (COL4A5-related) inherited?

Alport syndrome, X-linked (COL4A5-related) is an X-linked condition. X-linked conditions occur when there is a genetic variation on the X-chromosome. For these conditions, the sex of the parent who passes on the gene variation influences the risk for the children.

If the father is affected, all his daughters will have a variation on one of their X-chromosomes and be healthy carriers. Sons can only inherit these x-linked conditions from their mother and therefore, in this situation, will not be affected by the disease.

If the mother is a healthy carrier of an X-linked variation and has a son, there is a 50% chance that they could inherit this variant and be affected by the disease. If they have a daughter, there is a 50% chance that they will be a healthy carrier (just like her mum).

Another way of looking at this is that there is a 25% chance of having an affected son and a 75% chance that the child will not be affected by the disease.

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 Alport syndrome, X-linked (COL4A5-related), 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.

Learn more about carrier screening

Should parents screen for Alport syndrome, X-linked (COL4A5-related) before or early in pregnancy?

The biggest benefit of screening for Alport syndrome, X-linked (COL4A5-related) 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.