Megalencephalic leukoencephalopathy with subcortical cysts (MLC)
is a condition that affects brain development and function. Individuals with this condition have an enlarged brain (megalencephaly
) and an abnormality of the white matter in the brain (leukoencephalopathy
). White matter consists of nerve fibers covered by a fatty substance called myelin
that promotes the rapid transmission of nerve impulses. In MLC, the myelin is swollen and contains numerous fluid-filled pockets (vacuoles). Over time, the swelling decreases and the myelin begins to waste away (atrophy).
Leukoencephalopathy can lead to abnormal muscle tensing (spasticity
), difficulty coordinating movements (ataxia
), cysts in the brain (subcortical cysts), abnormal muscle tone (dystonia
), swallowing difficulties, mild to moderate intellectual disabilities, speech difficulties, seizures, and difficulties walking.
There are three types of MLC, which are distinguished by their signs and symptoms and genetic cause. Type 1 is caused by mutations
in the MLC1
gene. Types 2A and 2B are caused by mutations in the HEPACAM
gene. MLC types 1 and 2A are inherited in an autosomal recessive
manner, while type 2B is inherited in an autosomal dominant
manner. In approximately 5% of individuals with MLC, the cause is unknown.
Although there is no specific treatment or cure for MLC, there are ways to manage the symptoms, such as use of antiepileptic drugs, physical therapy, and speech therapy. Management additionally includes avoiding injury to the head, which can temporarily worsen symptoms. A team of doctors or specialists is often needed to figure out the treatment options for each person. 
Last updated: 9/7/2016
The chance to have another child with MLC varies depending on the the underlying cause. We recommend that you speak with a genetics professional to learn more about the specific risks to your future offspring. These type of professionals are a source of information for individuals and families regarding genetic diagnosis, natural history, treatment, mode of inheritance, and genetic risks to other family members. They can talk with you further about your testing options and risks to future offspring.
Last updated: 9/7/2016
Last updated: 7/15/2016
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
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