Our discovery of epistasis between Pax6 genotype and the B6 and 129 bkgds, producing severe microphthalmy and suppressed blood glucose levels, respectively, is congruent with earlier reports that Wt C57BL/6 mice spontaneously develop microphthalmia [73], and that Wt 129 Sv mice have low blood glucose levels [74]. Here, PAX6 is linked to microphthalmia.