ZIC antibodies in paraneoplastic cerebellar degeneration and small cell lung cancer

Patients with isolated ZIC4 antibodies usually have paraneoplastic cerebellar degeneration (PCD) and small cell lung cancer (SCLC) but the frequency is unknown. We analyzed the presence of ZIC1, ZIC2 and ZIC4 antibodies in 27 patients with PCD and SCLC negative for other onconeural antibodies. ZIC antibodies were detected in nitrocellulose filters with phage plaques. Four (15%) PCD sera recognized ZIC2. Three of these positive sera also reacted with ZIC1 and two with ZIC4. Our study suggests that 1) the incidence of isolated ZIC antibodies is low in PCD patients and SCLC and 2) ZIC antibodies are probably directed to epitopes shared by the three ZIC proteins.