HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease)

HBB-related hemoglobinopathies (including beta thalassemia) are a group of disorders that affect the way red blood cells are made. Red blood cells have 2 important building blocks (known as globin) - alpha and beta. The protein in red blood cells that carries oxygen throughout the body is called haemoglobin.

People with beta thalassemia don't make enough beta globin, which results in a lower amount of haemoglobin. Symptoms of beta thalassemia can include pale skin, weakness, fatigue, and more serious complications. In milder cases, patients may be healthy for long periods of time but are continually at risk for health problems such as anaemia and iron overload.

In severe cases, beta thalassemia can be life-threatening. Treatments such as blood transfusions and bone marrow transplants can be effective. For all HBB-related hemoglobinopathy disorders, early detection of the signs of the disorder and initiation of treatment is recommended.

Quick facts about HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease)
Genes: HBB
Inheritance: Autosomal Recessive
Alternative Names: Beta Thalassaemia, Sickle Cell Disease
Relevant resources for HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease)

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 HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease) inherited?

HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease) 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 HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease), 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 HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease), 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 HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease) before or early in pregnancy?

The biggest benefit of screening for HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease) 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 HBB-related hemoglobinopathies (inc. beta thalassemia and sickle cell disease) 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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