MGI:1924261 Mice homozygous for an ENU-induced allele are mostly hairless, with only a light patch of hair around the face and tail. Mice homozygous for a knock-out allele show embryonic lethality before implantation. In vitro outgrowth assays show that embryos fail to hatch from the zona pellucida and die after 3 days in culture, never forming blastocysts.