The heterogeneity of KFS has made it difficult to outline the diagnosis as well as the prognosis for this disease. Classification In 1912, Maurice Klippel and Andre<unk>  independently provided the first descriptions of KFS. They described patients who had a short, webbed neck; decreased range of motion (ROM) in the cervical spine; and a low hairline.<unk>  subsequently classified the syndrome into 3 categories: * Type I — Fusion of C2 and C3 with occipitalization of the atlas. In 1953, further complications were later reported by McRae; flexion and extension is concentrated within the C1 and C2 vertebrae. As with aging, the odontoid process can become hypermobile, narrowing the space where the spinal cord and brain stem travel (spinal stenosis). * Type II — Long fusion below C2 with an abnormal occipital-cervical junction. Similar to the C2-C3 fusion of McRae and could be viewed as a more elaborate variation. Flexion, extension, and rotation are all concentrated in the area of an abnormal odontoid process or poorly developed ring of C1 which cannot withstand the effects of aging. * Type III — A single open interspace between two fused segments. Cervical spine motion is concentrated at single open articulation. This hypermobility may lead to instability or degenerative osteoarthritis. This pattern can be recognized as the cervical spine is often seen to be at an angle or hinge at this open segment. A classification scheme for KFS was proposed in 1919 by Andre<unk> , which accounted for cervical, thoracic, and lumbar spine malformations. However, in 2006, Dino Samartzis and colleagues proposed three classification-types that specifically addressed the cervical spine anomalies and their associated cervical spine-related symptoms, with additional elaboration on various time-dependent factors regarding this syndrome.
Klippel–Feil syndrome
Srb's anomaly
Treacher Collins syndrome
Iniencephaly
Klippel–Trénaunay syndrome
Pelger–Huët anomaly
Laurence–Moon syndrome
Langer–Giedion syndrome