Leber congenital amaurosis (LCA) is a group of conditions that affect the retina - the light sensitive tissue in the back of the eye. People affected by LCA typically have severe visual impairment the is detected in infancy. The visual impairment is usually stable, however it can slowly worsen over time. Some people with LCA may have other symptoms such as increased sensitivity to light, involuntary eye movement or extreme farsightedness.
Sometimes, variants in the RPE65 gene are associated with a recessive form of a condition called Retinitis Pigmentosa (RP). RP is a group of conditions that also affect the retina. Symptoms of RP are usually detected in childhood or early adolescence. People with RP have difficulty seeing in low light and their vision progressively worsens over many years, ultimately resulting in total vision loss.
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.
Leber congenital amaurosis 2 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 Leber congenital amaurosis 2, there’s a one in four chance that their children could develop symptoms.
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 Leber congenital amaurosis 2, 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
The biggest benefit of screening for Leber congenital amaurosis 2 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 Leber congenital amaurosis 2 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.