Klippel-Feil syndrome (KFS) is a rare congenital disorder that is mainly characterized by abnormal fusion of two or more cervical vertebra of the spinal column. The abnormal fusion of these vertebra occurs as a result of a failure in the normal segmentation of cervical vertebra during the first weeks of fetal development. Usually, patients with KFS have an abnormally short neck, restricted movement of the head and neck, and/or a low hairline at the back of the head (posterior hairline); although less than 50% of patients demonstrate all these clinical features. In addition, some cases with KFS may present other physical abnormalities such as scoliosis (abnormal curvature of the spine), skeletal abnormalities like rib defects, hearing impairment, certain malformations of the head and facial (craniofacial) area, congenital heart defects, anomalies of the kidneys, respiratory problems, and abnormalities in the sex organs. Neurological complications may also appear in some cases due to associated spinal cord injury. Treatment methods for KFS are targeted toward associated symptoms and may include surgery to relieve cervical or craniocervical instability and constriction of the spinal cord, and to correct scoliosis. Also, physiotherapy practices show good results in KFS treatment. Early and proper treatment is the main factor of good prognosis for most cases with KFS.

Most KFS cases appear to occur sporadically. However, in other cases, KFS may be inherited as an autosomal dominant or autosomal recessive trait. Autosomal recessive KFS is mapped to the gene locus 17q21.31 and is caused by mutations in MEOX1 gene.