What is MLD?

MLD or metachromatic leukodystrophy is a rare, recessive genetic disorder that affects about 60 children born in the United States each year. I won't go into the science of it, the MLD Foundation and the National Institutes of Health can do a better job of that. What I will explain is what it has meant and will mean for Daniel and us.

MLD is affecting Daniel by destroying the myelin that coats his nerves and allows them to transmit signals. MLD, like other leukodystopies, attacks both his peripheral nerves and the nerves within his brain. Gross motor skills are the first thing Daniel lost because the peripheral nerve disease made it difficult for his hands and feet to receive signals and because the first part of the brain that is destroyed is the sector that control motor skills.

The disease at first proceeds slowly. Most kids, like Daniel, are diagnosed with other disorders. Walking problems are common and normally have other causes. Leukodystropies are rare.

MLD then starts to progress more rapidly. The peripheral nerve disease, which until now had center stage, is secondary to what is happening in the brain. Daniel lost his ability to walk and within months, he had problems sitting up. The MLD specialist described it as a cascade. The nerves within the brain reach a tipping point. Nerves that are healthy begin to self-destruct.

Once this happens, the disease progresses rapidly. Daniel in April could use his walker to go from the car, into the movie theater, get tickets and popcorn, and then head into the movie. Daniel in mid-May could only go 20 feet.

Daniel when he turns three in August probably will be unable to eat, drink, walk, or sit-up. Before he turns four, at the most, he will be able to rake his hands and move his head side to side. His speech, which will have been worsening over the past year, will cease. His vision will start to deteriorate. Eventually, he will lose his hearing.

While his ability to move and communicate is taken from him, Daniel will have seizures without careful use of anti-seizure medication. As the disease damages his brain, his muscles will painfully contract. Luckily, we can partially control that with muscle relaxers. The disease will eventually take enough of his brain that his muscles will relax.

Most children with MLD do not live beyond five. They do not die from the disease but complications such as infections or pneumonia from being unable to move. If a child lives until eight, nine, or later, MLD will attack the brain stem, leading to death.

 

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