In a previous study published by some of the authors (Titulaer et al., 2009), there was a similar level of SOX2 positivity of about 70% found in both LEMS-SCLC and a small group of patients with SCLC, ataxia and VGCC antibodies, without LEMS, indicating that perhaps it was the presence of pathogenic VGCC antibodies that was co-segregating with SOX antibodies. Here, SOX2 is linked to cerebellar ataxia.