Lysosomal storage disorders (LSDs) are inborn metabolic abnormalities characterized by the excessive accumulation of substrates in a variety of organ cells as a result of lysosome dysfunction. They contribute significantly to significant morbidity and mortality by causing malfunction in the organs where they accumulate. Dubbed as one of the most prevalent leukodystrophies in 2020, MLD has a prevalence rate of 1 occurrence in 40,000–160,000 births worldwide.
Now what is metachromatic leukodystrophy?
Metachromatic leukodystrophy (MLD) is a lysosomal storage disorder. The inability to break down sulphated glycolipids, particularly the galactosyl-3-sulphate ceramides is one of its defining characteristics. It is brought on by the lysosomal enzyme arylsulfatase A’s reduced activity, which is typically brought on by mutations in the arylsulfatase A gene (ARSA gene).
What happens to people with this condition?
This condition will lead to the accumulation of fatty substances (lipids) in cells, especially in the brain, spinal cord, and peripheral nerves. A lack of arylsulfatase A, an enzyme that aids in the breakdown of lipids, results in this accumulation. The lipid is known as sulfatide. As a result of the myelin (the substance that coats and protects the nerve cells) being damaged, the brain and nervous system gradually lose function.
What is the symptom and signs for this condition?
Each type of metachromatic leukodystrophy manifests itself at a different age, with different initial signs and symptoms and rates of progression:
In the first three years of life, symptoms are present in more than half of children. The term late-infantile MLD refers to this type. Walking difficulty is frequently one of the earliest symptoms of sickness brought on by demyelination of the peripheral nervous system.
Juvenile MLD (J-MLD) affects 20–30% of those with MLD and is less prevalent. The early indicators of J-MLD frequently involve behavioural issues or increased difficulty in school and the onset is between 4 years old and between 12 and 14 years of age.
MLD progresses in all of its forms. Most children with late-infantile MLD lose their abilities to walk and talk within months of the onset of symptoms. The development of the juvenile and adult forms might take years or even decades. Regardless of the subtype, the disease’s final stage is frequently distinguished by blindness, an inability to move, a lack of responsiveness, and a speech impediment.
How to detect this disease?
MLD is diagnosed using both genetic and biochemical tests. ARSA and PSAP gene mutations can be found by genetic testing. Sulfatase enzyme activity and urinary sulfatide excretion are included in biochemical tests.
A diagnosis of MLD may be confirmed by an MRI. A person’s brain is imaged during an MRI, which can also detect the presence or lack of myelin. The brains of those with MLD have a well-defined pattern of myelin loss. Imaging reveals growing brain injury as the disease worsens. It should be noted that early brain imaging in young children can be normal.
What is the treatment for this condition?
So far there is no specific medication for this condition. However, there is treatment that includes supportive care, reducing the disorder’s progression, minimising complications, and preventing nerve damage.
The most promising treatment for this condition is either undergoing bone marrow or umbilical cord blood transplant. Unfortunately, this treatment is not effective in repairing myelin that has already been damaged.
Conclusion
MLD is a rare genetic disease that needed further study to find a suitable treatment for people who experienced it. Even though there is a very promising treatment such as stem cell treatment, it still cannot repair myelin that has been damaged. Always refer to the doctor before you proceed with any treatment.
References
- Lamicchane, A., & Cabrero, F. R. (2022, July). Metachromatic Leukodystrophy. NCBI. https://www.ncbi.nlm.nih.gov/books/NBK560744/
- Metachromatic leukodystrophy – Symptoms and causes. (2020, March 6). Mayo Clinic. Retrieved September 6, 2022, from https://www.mayoclinic.org/diseases-conditions/metachromatic-leukodystrophy/symptoms-causes/syc-20354733
- Metachromatic Leukodystrophy (MLD) Symptoms, Treatment & Diagnosis. (2021, November 22). Hunter’s Hope. Retrieved September 6, 2022, from https://www.huntershope.org/family-care/leukodystrophies/metachromatic-leukodystrophy/
- NORD – National Organization for Rare Disorders. (2022, March 22). Metachromatic Leukodystrophy. NORD (National Organization for Rare Disorders). Retrieved September 6, 2022, from https://rarediseases.org/rare-diseases/metachromatic-leukodystrophy/
- Shaimardanova, A. A., Chulpanova, D. S., Solovyeva, V. V., Mullagulova, A. I., Kitaeva, K. V., Allegrucci, C., & Rizvanov, A. A. (2020, October 20). Metachromatic Leukodystrophy: Diagnosis, Modeling, and Treatment Approaches. Frontiers in Medicine, 7. https://doi.org/10.3389/fmed.2020.57622
