PITX3 and congenital primary aphakia: The so called aphakia mice lack the expression of Pitx3 due to a homozygote mutation in the Pitx3-gene resulting in a selective degeneration of mesencephalic dopaminergic neurons during embryonic development (Hwang et al., 2003; van den Munckhof et al., 2003; Smidt et al., 2004).