PAX1 and Klippel-Feil syndrome 1, autosomal dominant: PAX1 mutations were also detected in 8 out of 63 patients with Klippel-Feil syndrome (KFS), which is a human congenital condition, characterized by failed segmentation of the cervical vertebrae with the clinical sequelae of a short, immobile neck and a low posterior hairline (McGaughran et al., 2003).