In our analysis, 11 patients (Annus et al., 2018; Baik et al., 2018; Beauchemin et al., 2018; Bernard‐Valnet et al., 2019; Figueroa et al., 2014; Jin et al., 2019; Kon et al., 2017; Nakayama‐Ichiyama et al., 2011; Verschuur et al., 2015) performed AQP4 test in tumor tissue and seven of them are positive (7/11, 63.6%; Baik et al., 2018; Beauchemin et al., 2018; Bernard‐Valnet et al., 2019; Figueroa et al., 2014; Jin et al., 2019), four of them are negative (4/11, 36.3%; Annus et al., 2018; Kon et al., 2017; Nakayama‐Ichiyama et al., 2011; Verschuur et al., 2015). The gene discussed is AQP4; the disease is neoplasm.