Eleven published cases of patients presenting with epilepsy and secondary CSF neurotransmitter abnormalities underwent dopamine and serotonin replacement therapies; five had pathogenic variants in known disease-causing genes (SCN2A, KIAA2022, MECP2, FOLR2, and FGF13), and six had unknown aetiologies [6,13]. The gene discussed is MECP2; the disease is epilepsy.