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Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is an inherited disease that causes seizures and mild developmental delay in affected infants and children followed by deterioration in motor and mental skills later in life.
Many infants with MLC are born with disproportionately large heads while the remainder will develop this symptom in the first year of life. After the first year, the growth of the head usually normalizes, becoming proportionate to the body. This is typically accompanied by a mild delay in motor skills development and epileptic seizures.
Most, though not all, people with MLC learn to walk independently for at least several years. While some retain the ability to walk for decades, many will experience deteriorating motor skills beginning in early childhood. Initially their walking will become unstable and they may fall. As time goes on, they often develop the inability to coordinate muscle movement in their torso and limbs. Their movements may become uncontrollably jerky. The majority of these children will require wheelchairs by their early teens or in their 20s.
The decline in mental abilities begins after the decline in motor skills and is usually slower. People with MLC often develop speech problems
Brain scans typically show abnormal structures in the brains of people affected by MLC.
MLC is extremely rare, though its exact frequency in the general population is unknown. Mutations screened by Counsyl have been found in people of Middle Eastern, Turkish, Japanese, and Libyan Jewish descent, among others. One mutation is common in the Agrawali community in India. In the Libyan Jewish community, 1 in 34000 are affected.
There is no successful treatment for MLC, though anti-epileptic drugs can control seizures associated with the disease and physical therapy may help improve motor skills.
The prognosis for a person with MLC is not well understood, however people with the disease are often confined to a wheelchair in their early teens or 20s. Some people with the disease have died in their teens or 20s while other are known to be alive in their 40s.
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