MECP2-related severe neonatal encephalopathy is a rare disorder of males characterized by a static encephalopathy, severe developmental delays, hypotonia, seizures, and respiratory abnormalities that often leads to death at an early age. Mutations in the MECP2 gene cause this disease, and females with these same mutations typically have a disorder called Rett syndrome. Most boys with this disorder have been identified because they have female siblings with Rett syndrome.
