ARX and developmental and epileptic encephalopathy: Pathogenic variants in ARX have a striking genotype–phenotype correlation, with loss‐of‐function alleles leading to neurodevelopmental phenotypes, for example, X‐linked lissencephaly with abnormal genitalia (XLAG), whereas missense variants outside of the homeodomain and polyalanine tract expansions generally lead to a broad range of DEE/epilepsy‐dyskinesia phenotypes with grossly normal cortical brain structure, such as early‐infantile developmental and epileptic encephalopathy, infantile spasms, or myoclonic epilepsy.6