Congenital scoliosis (CS) is a common spinal anomaly and spondylo-costal dysostosis (SCDO) is a rare skeletal dysplasia affecting spine and rib. They have been considered to belong to different disease entities. We examined TBX6 in CS and SCDO and found loss-of-function (LOF) mutations in both. There were two LOF mechanisms: decreased transcriptional activity and mis-localization of the protein. The latter was the main pathogenicity and was confirmed by in vitro model of somitegenesis using iPS cells from a SCDO patient. Bi-allelic LOF of TBX6 causes a spectrum of malformations including CS and SCDO, depending on the severity of LOF. (Drs. Shiro Ikegawa and Nao Otomo, https://jmg.bmj.com/content/early/2019/04/17/jmedgenet-2018-105920)