TBCD and Perlman syndrome: Closest homologues of Sts5 include S. cerevisiae Ssd1 (Jansen et al., 2009), S. pombe Dis3L2, and the human exonuclease Dis3L2, which has been associated with diseases such as Perlman syndrome and Wilm’s tumor, as well as Rrp44/Dis3 (Figure 1C) (Malecki et al., 2013; Robinson et al., 2015; Lv et al., 2015; Astuti et al., 2012).