Pitx2 mutations cause Axenfeld-Rieger syndrome type 1, a congenital malformation syndrome affecting the anterior eye [46,47] iridogoniodysgenesis type 2 (iris hypoplasia) [48], Peters' anomaly (defective cornea) [49] and ring dermoid of the cornea [50]. The gene discussed is PITX2; the disease is anterior segment dysgenesis 4.