MGI:98387Homozygotes for a spontaneous mutation exhibit a severe microcytic anemia with erythrocyte fragility, hepatomegaly and jaundice and die within a few days of birth. Homozygotes for a knock-out allele show complete embryonic lethality before implantation. In vitro, embryos fail to hatch from the zona pellucida and die after 3 days in culture, never forming outgrowths.