Megalencephalic Leukoencephalopathy with Subcortical Cysts (LVM)

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MedlinePlus Genetics: ⁴² Megalencephalic leukoencephalopathy with subcortical cysts is a progressive condition that affects brain development and function. Individuals with this condition typically have an enlarged brain (megalencephaly) that is evident at birth or within the first year of life. Megalencephaly leads to an increase in the size of the head (macrocephaly). Affected people also have leukoencephalopathy, an abnormality of the brain's white matter. White matter consists of nerve fibers covered by a fatty substance called myelin. Myelin insulates nerve cells (neurons) and promotes the rapid transmission of nerve impulses. In megalencephalic leukoencephalopathy with subcortical cysts, the myelin is swollen and contains numerous fluid-filled pockets (vacuoles). Over time, the swelling decreases and the myelin begins to waste away (atrophy). Individuals affected with this condition may develop cysts in the brain; because these cysts form below an area of the brain called the cerebral cortex, they are called subcortical cysts. These cysts can grow in size and number.The brain abnormalities in people with megalencephalic leukoencephalopathy with subcortical cysts affect the use of muscles and lead to movement problems. Affected individuals typically experience muscle stiffness (spasticity) and difficulty coordinating movements (ataxia). Walking ability varies greatly among those affected. Some people lose the ability to walk early in life and need wheelchair assistance, while others are able to walk unassisted well into adulthood. Minor head trauma can further impair movements and may lead to coma. Affected individuals may also develop uncontrolled muscle tensing (dystonia), involuntary writhing movements of the limbs (athetosis), difficulty swallowing (dysphagia), and impaired speech (dysarthria). More than half of all people with this condition have recurrent seizures (epilepsy). Despite the widespread brain abnormalities, people with this condition typically have only mild to moderate intellectual disability.There are three types of megalencephalic leukoencephalopathy with subcortical cysts, which are distinguished by their signs and symptoms and genetic cause. Types 1 and 2A have different genetic causes but are nearly identical in signs and symptoms. Types 2A and 2B have the same genetic cause but the signs and symptoms of type 2B often begin to improve after one year. After improvement, individuals with type 2B usually have macrocephaly and may have intellectual disability.

MalaCards based summary: Megalencephalic Leukoencephalopathy with Subcortical Cysts, also known as vacuolating megalencephalic leukoencephalopathy with subcortical cysts, is related to megalencephalic leukoencephalopathy with subcortical cysts 2a and megalencephalic leukoencephalopathy with subcortical cysts 1, and has symptoms including ataxia, seizures and muscle spasticity. An important gene associated with Megalencephalic Leukoencephalopathy with Subcortical Cysts is MLC1 (Modulator Of VRAC Current 1), and among its related pathways/superpathways are Sudden infant death syndrome (SIDS) susceptibility pathways and Miscellaneous transport and binding events. Affiliated tissues include brain, cortex and temporal lobe, and related phenotypes are homeostasis/metabolism and nervous system

GARD: ¹⁹ 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 genetic changes in the MLC1 gene. Types 2A and 2B are caused by genetic changes 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 some cases of MLC, the cause is unknown.

Orphanet: ⁵⁸ A form of leukodystrophy that is characterized by infantile-onset macrocephaly, often with mild neurologic signs at presentation (such as mild motor delay), which worsen with time, leading to poor ambulation, falls, ataxia, spasticity, increasing seizures and cognitive decline. Brain magnetic resonance imaging reveals diffusely abnormal and mildly swollen white matter as well as subcortical cysts in the anterior temporal and frontoparietal regions.

Disease Ontology: ¹¹ A leukodystorphy characterized by infantile-onset macrocephaly, often with mild neurologic signs at presentation (such as mild motor delay), which worse with time, leading to poor ambulation, falls, ataxia, spasticity, increasing seizures and cognitive decline.

Wikipedia: ⁷⁵ Megalencephalic leukoencephalopathy with subcortical cysts (MLC, or Van der Knaap disease) is a form of... more...

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