PAX6 and Hypoplasia of the iris: Haploinsufficiency in the mouse Pax6 gene results in a clinical model of aniridia with iris hypoplasia being prevalent; while modulation of Pitx2 and Foxc1 gene dose results in pupil and drainage structure abnormalities and thus represent experimental models of ARS (Baulmann et al., 2002; Gage et al., 1999; Hill et al., 1991; Hogan et al., 1988; Holmberg et al., 2004; Lines et al., 2002; Ramaesh et al., 2003; Smith et al., 2000).