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MLD Treatment

Taylor Kjorsvik

Mar 13, 2024

What is Metachromatic leukodystrophy (MLD)? MLD is a rare hereditary disease characterized by accumulations of fats called sulfatides. This causes deterioration of myelin sheath, the protective layer surrounding the nerves in the central and peripheral nervous system. There are 3 different types of MLD, diagnosed by whichever age someone’s symptoms appear at. Late infantile MLD, Juvenile MLD, and Adult MLD. All 3 types affect motor and intellectual functions. “Symptoms vary by type but can include difficulty talking, seizures, difficulty walking, personality changes, and behavior and personality changes” (NORD 2024). Metachromatic leukodystrophy is caused by mutations in the ARSA gene and sometimes the PSAP gene. Usually children with Late infantile MLD die before age 5, those with Juvenile MLD tend to die after 10-20 years from when first symptoms occurred, people with Adult MLD die after 6-14 years following onset symptoms. A new gene therapy for this fatal disorder has just come out, however, it is now the most expensive drug in the world at a wholesale price of $4.25 million. This has raised many questions about access. “Lenmeldy was approved by the US Food and Drug Administration on Monday and is the first therapy for the rare and devastating disease, which typically kills affected children before they turn 7” (CNN). Before now the only thing to possibly delay the process of MLD was a bone marrow transplant and only in some infantile-onset cases. How does Lenmeldy work? They take stem cells from someone with Metachromatic Leukodystrophy and use a harmless virus to insert copies of faulty genes. The repaired cells are infused back into the patient, and they begin to produce enzymes that the person with the disease is lacking, “Some of the cells eventually migrate to the bone marrow, where they continue to live and make new cells that also make the enzyme, providing a long-lasting benefit to patients” (CNN).   

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