The mouse rib-vertebrae mutation is a hypomorphic Tbx6 allele.

Rib-vertebrae (rv) is an autosomal recessive mutation in mouse that affects somite formation, morphology, and patterning. Expression of Notch pathway components is affected in the paraxial mesoderm of rv mutant embryos, and rv and a null allele of the Notch ligand delta1 show non-allelic non-complementation. By fine genetic mapping and complementation testing we have identified Tbx6, a gene essential for paraxial mesoderm formation, as the gene mutated in rv.