The Noggin Null Mouse Phenotype Is Strain Dependent and Haploinsufficiency Leads to Skeletal Defects

The study found that the effects of Noggin gene inactivation in mice were dependent on the genetic background, with Noggin null mice showing varied skeletal and muscular defects across different strains. In the CD1 strain, these mice had less severe limb bud phenotypes. The absence of Noggin led to inconsistent bone mineralization, with some bones showing accelerated ossification and others delayed or unaffected. Noggin haploinsufficiency caused carpal and tarsal fusions, similar to human phenotypes, and impaired terminal muscle differentiation. The study underscored the importance of genetic background in the phenotypic manifestation of Noggin inactivation and suggested potential genetic modifiers influencing these phenotypes.