Is megalencephalic leukoencephalopathy with subcortical cysts inherited ?
All cases of megalencephalic leukoencephalopathy with subcortical cysts caused by mutations in the MLC1 gene (type 1) and some cases caused by mutations in the HEPACAM gene (type 2A) are inherited in an autosomal recessive pattern. Autosomal recessive inheritance means both copies of a gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.  Megalencephalic leukoencephalopathy with subcortical cysts type 2B is inherited in an autosomal dominant pattern, which means one copy of the altered HEPACAM gene in each cell is sufficient to cause the disorder. Most cases of type 2B result from new (de novo) mutations in the HEPACAM gene that occur during the formation of reproductive cells (eggs or sperm) or in early embryonic development. These cases occur in people with no history of the disorder in their family.