FGF18 and omphalocele: To analyze the role of Fgf17 further we considered double mutants in which Fgf17 was inactivated along with either Fgf8 or Fgf18. In such mutants (TCre;Fgf8f/Δ;Fgf17Δ/Δ;Fgf18+/+ and TCre;Fgf8+/+;Fgf17Δ/Δ;Fgf18f/Δ) the incidence of omphalocele was 4% and 7%, respectively (Fig. 2G).