RTEL1 (regulator of telomere length 1) was identified as a cancer susceptibility gene (Shete et al. 2009; Wrensch et al. 2009; Vannier et al. 2014) and implicated in a number of telomere dysfunction syndromes (Ballew et al. 2013a,b; Deng et al. 2013; Le Guen et al. 2013; Walne et al. 2013). This evidence concerns the gene RTEL1 and cancer.