Epitranscriptomic regulation in major brain disorders. Epitranscriptomic RNA modifications are involved in multiple types of brain disorders. Human genetic analysis and animal model studies revealed that various RNA modifications and their regulatory machineries have critical roles in etiology of neurogenerative disorders, intellectual disability, mental disorders, and brain cancers. ADHD, attention deficit hyperactivity disorder; MLASA, mitochondrial myopathy, lactic acidosis, and sideroblastic anemia; XLMR, X-linked mental retardation; m6A, N6-methyladenosine; ψ, pseudouridine; m5C, 5-methylcytosine; Nm, 2’-O-methylation.