Homozygous Null Knockout Mouse Embryos Are Lethally Stopped in Their Early Development.

Although the conditional gene knockout (KO) is a better choice for observing its phenotype in a specific cell, tissue, and/or organ, the simple null gene KO could nevertheless be attempted initially to scan its overall phenotypes at the level of the whole-body system, especially for a new gene such as . Therefore, with a hope to glean phenotypic clues for at the whole-body system, we attempted to generate its null KO mice. Contrary to our original desire, homozygous null KO mice were not born. However, in the chasing of their homozygous KO embryos, they were found to be lethally impaired from early development, remaining in a state of small globular mass without ever leading to a body shape, indicating the critical role of as a Wnt target gene for the proliferation and/or differentiation of cells during early mouse embryonic development.