First, several of the approximately 1000 genes located on the X have been implicated in cancer, including the cancer/testis (C/T) genes (Grigoriadis et al. 2009); tumor suppressors such as AMER1 (also known as WTX), FOXP3 (Bennett et al. 2001; Rivera et al. 2007); chromatin remodelers related to disease, e.g., ATRX; or chromatin modifying factors, e.g., KDM6A (also known as UTX), PHF8, HDAC8 (Nakagawa et al. 2007; for reviews, see Agrelo and Wutz 2010; Portela and Esteller 2010). Here, ATRX is linked to cancer.