Metachromatic leukodystrophy (MLD) is a rare genetic condition that causes a buildup of a specific type of fat (sulfatides) in brain and spinal cord cells. This buildup causes leukodystrophy, which is progressive destruction of cells that have a myelin coating (white matter) in the brain and spinal cord. Destruction of these cells leads to the inability to think clearly and perform physical tasks. Individuals with MLD lose the ability to perform daily functions over time, such as talking and walking. As the disease progresses, individuals lose awareness of where they are and eventually become unresponsive. Blindness, seizures and hearing loss may also occur. There are three forms of MLD: late infantile form, juvenile form, and adult form. The late infantile form, which is the most common form, begins in the second year of life and progresses rapidly. The juvenile form typically begins between 4 years of age and teenage years, while the adult form starts after the teenage years.
MLD, which is an autosomal recessive condition, occurs when a person has mutations (changes) in both copies of the ARSA gene. This gene tells the body how to make the arylsulfatase A enzyme, which is responsible for breaking down sulfatides within cells. A decrease in this enzyme leads to the buildup of sulfatides within the cell. A doctor can diagnose MLD by collecting a medical history and performing a physical exam, as well as performing brain-imaging tests. A magnetic resonance imaging (MRI) test may be used to check for signs of leukodystrophy in the brain. Genetic testing of the ARSA gene is typically performed to confirm the diagnosis. There is currently not a cure for MLD. Treatment involves addressing symptoms of MLD, such as seizure control. This is a very serious condition and, if you or your child has this diagnosis, it may be helpful to speak with a doctor or therapist to gain additional information and support.