Alpha thalassemia X-linked intellectual disability (ATRX) syndrome is a condition that affects many systems in the body. Males born with this condition usually show signs from when they are born, including low muscle tone (hypotonia), developmental delay, intellectual disability, genital differences and distinctive facial features. They also have mild to moderate anemia due to a blood condition called alpha-thalassemia. Alpha-thalassemia is a condition where the body does not produce enough hemoglobin which is an important part of the red blood cells that carry oxygen around the body.
The physical features of the condition range from a big impact to not very noticable but the impact on development and intellect are severe. People with this condition have difficulty with speech development and may never be able to talk.
Because it is X-linked, ATRX affects males and female carriers are not usually affected. However, a small number of females who carry a variation in this gene may experience some signs of the condition including specific changes seen in blood tests called HbH inclusions.
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.
alpha-thalassemia X-linked intellectual disability syndrome 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.
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 alpha-thalassemia X-linked intellectual disability syndrome, 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 alpha-thalassemia X-linked intellectual disability syndrome 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.