In this study, we found only two patients (one LEMS-SCLC patient and one non-tumour LEMS patient) had positive SOX2 antibodies but negative SOX1 antibodies, and all positive LEMS samples were confirmed by Western blotting to purified recombinant SOX antigen as previously described (Titulaer et al., 2009). This evidence concerns the gene SOX1 and Lambert-Eaton myasthenic syndrome.