Monarch Disease Ontology term MONDO_0010397 (severe neonatal-onset encephalopathy with microcephaly) is an X-linked recessive condition caused by mutation(s) in the MECP2 gene, encoding methyl-CpG-binding protein 2. It is characterized by severe neonatal encephalopathy. Also known as: encephalopathy, neonatal severe, X-linked recessive, severe congenital encephalopathy due to MECP2 mutation, severe neonatal encephalopathy due to MECP2 mutations.