YAP1 and coloboma: <i>wwtr1</i> homozygotes do not have coloboma, while <i>yap1</i> homozygotes have coloboma and pigment defects which are exacerbated by absence of one copy of <i>wwtr1</i> (<i>yap1</i> <sup><i>-/-</i></sup> <i>; wwtr1</i> <sup>+<i>/-</i></sup> ).