Abrogation of LBX1 in skeletal muscle results in hypoplastic limbs and progressive kyphosis in mice.

LBX1 is a gene located near a single-nucleotide polymorphism, rs11190870, which is highly associated with susceptibility to adolescent idiopathic scoliosis. However, the potential involvement of LBX1 in the etiology of this spinal deformity has not been elucidated. In this study, we aimed to determine whether the lack of LBX1 in skeletal muscle results in spinal deformities in mice. We generated mutant mice in which the Lbx1 allele was conditionally excised under the control of a human muscle actin promoter. Mice lacking LBX1 from the skeletal muscle were fertile and available. The mutant mice had hypoplastic forelimbs and weighed less than control animals, but otherwise, there were no overt anomalies. The mice did not exhibit a scoliosis-like spinal deformity; however, they developed moderate kyphosis as they grew old. These observations indicated that LBX1 is involved in limb development and potentially in the maintenance of spinal curvature/alignment in mice.