• Lrp6;
  • canonical Wnt/β-catenin signaling pathway;
  • conditional gene-targeting;
  • loxP-Cre;
  • birth defects;
  • congenital diseases;
  • neural tube defects;
  • spina bifida;
  • limb defects;
  • oligodactyly;
  • microphthalmia;
  • ocular coloboma;
  • cleft lip;
  • external genitalia


Lrp6 is a key coreceptor in the canonical Wnt pathway that is widely involved in tissue/organ morphogenesis. We generated a loxP-floxed Lrp6 mouse line. Crossing with a general Cre deleter, we obtained the Lrp6-floxdel mice, in which the loxP-floxed exon 2 of Lrp6 gene has been deleted ubiquitously. The homozygotes of Lrp6-floxdel mice reproduced typical defects as seen in the conventional Lrp6-deficient mice, such as defects in eye, limb, and neural tube, and die around birth. We also found new phenotypes including cleft palate and agenesis of external genitalia in the Lrp6-floxdel mice. In addition, the Lrp6-deficient embryos are known to be defective in other systems and internal organs including the heart and brain. Thus, by selectively crossing with a lineage-specific or inducible Cre mouse line, the Lrp6 conditional gene-targeting mice will allow us to model specific types of birth defects for mechanism and prevention studies. Developmental Dynamics 239:318–326, 2010. © 2009 Wiley-Liss, Inc.