DND1 and teratoma: In the 129 strain, the Dnd1-Δ allele significantly increased teratoma occurrence in male mice from a baseline of 4.2% to 28.8% in Dnd1+/Δ heterozygotes and 92.6% in Dnd1Δ/Δ homozygotes, which are ratios similar to those for Ter mutant mice [4, 5, 16, 21].