Klippel-Feil syndrome is an autosomal dominant disorder characterised by congenital fusion of two or more cervical vertebra. The classic clinical triad of short neck, low hair line, and restricted neck motion is present in less than 50% of patients with this syndrome. This disorder results from failure of normal segmentation of the somites during the 3rd to 8th week of gestation. Three types of Klippel-Feil syndrome have been described: type 1, cervical spine fusion in which elements of many vertebra are incorporated into a single block; type 2, cervical spine fusion in which there is failure of complete segmentation at only one or two cervical levels and may include an occipito-atlantal fusion; and type 3, both cervical fusion and lower thoracic or lumbar fusion with co-existing segmentation errors in the lower dorsal or lumbar spine. Deafness is a common associated feature and may be of sensorineural, conductive, or mixed type, and with a slight excess of females (M:F ratio 1:1.5).
Mutations in GDF6 gene is associated with Klippel-Feil syndrome.