Mutations of the GDF6, GDF3 and MEOX1 gene are associated with KFS. The cause of the condition is unknown in individuals with KFS who do not have mutations of these two genes. GDF6 and GDF3 provide the body with instructions for making proteins involved in regulating the growth and maturation of bone and cartilage. GDF6 specifically is involved in the formation of vertebral bones, among others, and establishing boundaries between bones in skeletal development. GDF3 is involved with bone and cartilage growth. Mutations of GDF6, GDF3 and MEOX1 cause a reduced number of functional proteins that are coded by these genes, but it is unclear exactly how a shortage in these proteins leads to incomplete separation of the vertebrae in people with KFS. However, when the GDF6 gene was removed in mice, the result was the fusion of bones. These mutations can be inherited in two ways: * Autosomal dominant inheritance, where one copy of the altered gene in each cell is sufficient to cause the disorder, is especially associated with C2-C3 fusion. * Autosomal recessive inheritance, where both copies of a gene contain mutations, is especially associated with C5-C6 fusion. * Another autosomal dominant form (mapped on locus 8q22.2), known as KFS with laryngeal malformation, has been identified. It is also known as segmentation<unk>  1.
Klippel–Feil syndrome
Srb's anomaly
Treacher Collins syndrome
Iniencephaly
Klippel–Trénaunay syndrome
Pelger–Huët anomaly
Laurence–Moon syndrome
Langer–Giedion syndrome