Monarch Disease Ontology term MONDO_0011391 (megalencephalic leukoencephalopathy with subcortical cysts) (MLC) is 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. Also known as: MLC, Vacuolating megalencephalic leukoencephalopathy with subcortical cysts, Van der Knaap syndrome, megalencephalic leukodystrophy, megalencephalic leukoencephalopathy with subcortical cysts type 1, megalencephaly-cystic leukodystrophy syndrome.