CDR2 and paraneoplastic neurologic syndrome: These antibodies can be divided into three subgroups: Ia, containing the classical onconeuronal antibodies, such as anti-Hu, anti-Yo and anti-Ri; Ib, cancer-associated antibodies (SOX and ZIC) lacking an association with an immune response causing a paraneoplastic syndrome (PNS); and Ic, non-PNS antibodies, including glutamate decarboxylase, associated with cerebellar ataxia.