The spectrum of new autoantibodies keeps expanding. Last year, Mandel-Brehm and colleagues discovered Kelch-like protein 11 (KLHL11) as a novel antigen for paraneoplastic cerebellar ataxias using T7 phage display, a relatively new method. 1 Bacteriophage (phage) display was first described by George Smith, for which he was awarded the 2018 Nobel Prize in Chemistry. 2 In 2011, a modified human programmable T7 display system engineered to screen for novel antigens was described, 2 an approach now used by Mandel-Brehm and colleagues. 1,2 Since the original description of anti-KLHL11 disease, based on an index case and 12 additional male patients, 72 additional patients (16 women, 22%) have been reported. [3][4][5] It appears that, with an estimated prevalence of 1.4 per 100,000 people, 1 anti-KLHL11 disease is one of the most common paraneoplastic syndromes. For comparison, the prevalence of Ri autoantibodies is~0.6 per 100,000 people. 6 The core phenotype is rhombencephalitis, most frequently presenting with cerebellar signs, often with additional brainstem findings (eg vertigo, tinnitus, hearing loss, diplopia); with subsequently identified cases, there is a widening spectrum including also opsoclonus-myoclonus, encephalopathy, myeloneuropathy, and cervical amyotrophy. 3,5 The clinical onset is usually in early-middle adulthood (range 9-76 years). There is a strong tumor association, mostly with germ cell tumors, especially (extra-)testicular seminomas. Much more rarely, lung cancer and chronic lymphocytic leukemia are found. 3,5 MRI findings are diverse, ranging from normal to cerebellar atrophy, cerebellar nuclei T2-hyperintensities, leptomeningeal enhancement, or mesiotemporal abnormalities. When reported, CSF is abnormal with intrathecal IgG synthesis, hyperproteinorrachia or pleocytosis. Often, there are >8 unmatched oligoclonal bands, suggesting intrathecal antibody production. This may be a diagnostic clue and is in line with the presence of concomitant autoantibodies, seen in 44% of the patients, mainly against Ma2 and NMMDAR, as expected in patients with seminomas and teratomas. 3