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Genetic and Rare Diseases Information Center (GARD)

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Megalencephalic leukoencephalopathy with subcortical cysts


Other Names for this Disease

  • Leukoencephalopathy with swelling and cysts
  • LVM
  • Megalencephaly-cystic leukodystrophy
  • MLC
  • Vacuolating megalencephalic leukoencephalopathy with subcortical cysts
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

I have a daughter with megalencephalic leukoencephalopathy with subcortical cysts. Can I expect to have a healthy baby in the next pregnancy? Who can I talk to about this?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is megalencephalic leukoencephalopathy with subcortical cysts (MLC)?

Megalencephalic leukoencephalopathy with subcortical cysts is a condition that affects brain development and function. Children with this condition have an enlarged brain (megalencephaly) that is evident at birth or within the first year of life. They also have an abnormality of the brain's white matter (leukoencephalopathy). The leukoencephalopathy may ultimately result in abnormal muscle tensing (spasticity), difficulty coordinating movements (ataxia), cysts in the brain (subcortical cysts), abnormal muscle tone (dystonia), swallowing difficulties, speech difficulties, and seizures. Despite the brain abnormalities people with this condition tend to have only mild to moderate learning impairment. This condition may affect a child’s ability to walk, however some children are able to walk well into adulthood. It is important to protect people with MLC from even mild head trauma, because head trauma can cause further impairments and may lead to coma. This condition is genetic and is passed through families in an autosomal recessive pattern. It is most often caused by changes in the MLC1 gene.[1]
Last updated: 6/4/2009

What causes megalencephalic leukoencephalopathy with subcortical cysts (MLC)?

In most cases MLC is caused by mutations in the MLC1 gene and is passed through families in an autosomal recessive pattern. 

Some people with MLC do not have detectable mutations in this gene. In these cases (about 25%) the cause of their condition is unknown. It is possible that there are genes other than MCL1 involved in causing MLC that have yet to be identified.[1]
Last updated: 6/4/2009

What is autosomal recessive inheritance?

Autosomal recessive inheritance refers to the inheritance pattern in which two mutated copies of the gene that causes a disorder are present in each cell. An affected person usually has unaffected parents who each carry a single copy of the mutated gene (and are referred to as carriers). Autosomal recessive disorders are typically not seen in every generation of an affected family. When two people who are carriers of an autosomal recessive condition have a child, there is a 25% (1 in 4) chance that the child will be affected.[2]

Last updated: 2/18/2009

I have one child with megalencephalic leukoencephalopathy with subcortical cysts. Can I expect to have a healthy baby in my next pregnancy?

With autosomal recessive inheritance there is a 1 in 4 or 25% chance with each pregnancy that the child will be affected and a 75% or 3 in 4 chance that the child will not be affected. 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 regarding your testing options and risks to future offspring. To find a genetics clinic, we recommend that you contact your primary doctor for a referral. Click here to learn more about genetic consultations.

The following online resources can also help you find genetics professionals in your community:

  • GeneTests - A searchable directory of US and international genetics and prenatal diagnosis clinics. Go to the following link and click on 'Clinic Directory' to find a genetic service close to you.
  • American Society of Medical Genetics – A membership directory of genetics specialists around the world.
Last updated: 6/4/2009

References
Other Names for this Disease
  • Leukoencephalopathy with swelling and cysts
  • LVM
  • Megalencephaly-cystic leukodystrophy
  • MLC
  • Vacuolating megalencephalic leukoencephalopathy with subcortical cysts
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.