TGIF1 and otitis media: Although Tgif1 and Tgif2 single null mice are relatively normal on a mixed strain background, transferring a Tgif1 mutation to a relatively pure C57BL/6 strain results in approximately 50% perinatal lethality of the Tgif1 nulls, placental defects and otitis media in the weaned mice [31, 32].