Null mutations of Tbx6, a key regulator of the Notch signaling pathway, cause congenital scoliosis in humans and rats.27, 52, 53, 54 However, the vertebral defects may occur in the cervical, thoracic, or lumber spine, in contrast to Hvf mice, in which the defects occurred only in L2 to L5 vertebrae. This evidence concerns the gene TBX6 and scoliosis.