Consistent with these differential expression patterns, germline Six2 deletion in mice leads to renal hypoplasia due to depletion of the nephron progenitors (Self et al., 2006), while Six1 knockout causes renal agenesis due to malformation of the MM (Li et al., 2003; Xu et al., 2003; Kobayashi et al., 2007; Nie et al., 2011; Xu and Xu 2015). Here, SIX1 is linked to renal agenesis.