3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency

3-hydroxy-3-methylglutaryl-CoA lyase deficiency (HMG-CoA lyase deficiency) is a metabolic disorder that prevents the body from being able produce two important molecules that are used for energy during periods without food. Children affected by HMG-CoA lyase deficiency can experience episodes of vomiting, dehydration, extreme tiredness (lethargy), and low blood sugar levels (hypoglycemia), which can cause a buildup of harmful compounds in the blood, making it too acidic (metabolic acidosis). Early detection and treatment, including dietary management, can often prevent the serious consequences of this disorder. Without treatment, the disorder can lead to breathing problems, seizures, coma, and death. Episodes can be triggered by infections, periods without food (fasting), exercise, and stress.

Quick facts about 3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency
Genes: HMGCL
Inheritance: Autosomal Recessive

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 3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency inherited?

3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency 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 3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency, 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 3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency, 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 3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency before or early in pregnancy?

The biggest benefit of screening for 3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency 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 3-hydroxy-3-methylglutarayl-CoA (HMG-CoA) lyase deficiency 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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