TTK is expressed at relatively high levels in testis, thymus tissues and various malignant tumor tissues (Kaistha et al. 2014; Miao et al. 2016; Choi et al. 2017; Szymiczek et al. 2017; Chen et al. 2018; King et al. 2018), but is not detected in most other benign tissues (Mills et al. 1992). The gene discussed is TTK; the disease is cancer.