IMCAs are a rare spectrum of diseases, and several specific neuronal antibodies were identified in IMCAs, such as the onconeural antibodies (Yo-Ab, Hu-Ab, CV2-Ab, Ri-Ab, and Ma-2-Ab) for PCDs, GAD65-Ab for anti-GAD65 Ab-associated CA, and Ri-Ab for OMS (15–20). The gene discussed is GAD2; the disease is opsoclonus-myoclonus syndrome.