Metachromatic leukodystrophy

Metachromatic leukodystrophy (MLD) causes problems with the lysosomes, which are structures in the cell that break down and recycle other molecules.

Individuals with MLD have difficulty breaking down certain fats called sulfatides, which can cause progressive problems with intellect and motor functions that get worse over time. Seizures, dementia, paralysis, pain and reduced sensation due to nerve damage, typically in the hands and feet, and vision and hearing loss are common symptoms of the condition.

There are three types of MLD, which vary by age of onset and severity of symptoms. For all forms of MLD, treatment is focused on managing the symptoms.

Quick facts about metachromatic leukodystrophy
Genes: ARSA
Inheritance: Autosomal Recessive
Alternative Names: mld
Relevant resources for metachromatic leukodystrophy

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 metachromatic leukodystrophy inherited?

metachromatic leukodystrophy 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 metachromatic leukodystrophy, 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 metachromatic leukodystrophy, 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 metachromatic leukodystrophy before or early in pregnancy?

The biggest benefit of screening for metachromatic leukodystrophy 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 metachromatic leukodystrophy 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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