The prevalence of Klippel–Feil syndrome is unknown due to the fact that there was no study done to determine the true prevalence.

Although the actual occurrence for the KFS syndrome is unknown, it is estimated to occur 1 in 40,000 to 42,000 newborns worldwide. In addition, females seem to be affected slightly more often than males.

Genetic genealogy has identified a specific location of a gene on a chromosome for Klippel-Feil Syndrome. Mutations in the GDF6 and GDF3 genes have also been identified to cause the disease, although some people with Klippel–Feil syndrome do not have identified mutations in the GDF6 or GDF3 genes. In this case, the cause of the condition in these individuals is unknown. GDF6 and GDF3 genes provide the body with instructions for making proteins involved in regulating the growth and maturation of bone and cartilage. These proteins actively regulate cell growth in embryonic and adult tissue. GDF6 specifically is involved in the formation of vertebral bones, among others, and establishing boundaries between bones in skeletal development while GDF3 is involved with bone and cartilage growth. Mutations cause reductions in these functional proteins but, it is unclear exactly how a shortage in these proteins leads to incomplete separation of the vertebrae in people with Klippel–Feil syndrome. However, when the GDF6 gene was knocked out in mice, the result was the fusion of bones. Only by identifying the link between the genetic cause and the phenotypic pathoanatomy of Klippel–Feil syndrome will we be able to rationalize the heterogeneity of the syndrome.

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 Klippel–Feil syndrome with laryngeal malformation has been identified. It is also known as Segmentation syndrome 1.

The incidence of VACTERL association is estimated to be approximately 1 in 10,000 to 1 in 40,000 live-born infants. It is seen more frequently in infants born to diabetic mothers. While most cases are sporadic, there are clearly families who present with multiple involved members.

Patients with abnormal cardiac and kidney function may be more at risk for hemolytic uremic syndrome

Studies have shown that obesity of the mother increases the risk of neural tube disorders such as iniencephaly by 1.7 fold while severe obesity increases the risk by over 3 fold.

Once a mother has given birth to a child with iniencephaly, risk of reoccurrence increases to 1-5%.

Vertebral anomalies is associated with an increased incidence of some other specific anomalies as well, together being called the VACTERL association:

- V - "Vertebral anomalies"

- A - Anal atresia

- C - Cardiovascular anomalies

- T - Tracheoesophageal fistula

- E - Esophageal atresia

- R - Renal (Kidney) and/or radial anomalies

- L - Limb defects

Midline cervical clefts are a rare congenital anomaly resulting from incomplete fusion during embryogenesis of the first and second branchial arches in the ventral midline of the neck. The condition presents as a midline cutaneous defect of the anterior neck with a skin projection or sinus, or as a subcutaneous erythematous fibrous cord. Surgical excision is the preferred treatment.

Diastematomyelia (occasionally diastomyelia) is a congenital disorder in which a part of the spinal cord is split, usually at the level of the upper lumbar vertebra.

Diastematomyelia is a rare congenital anomaly that results in the "splitting" of the spinal cord in a longitudinal (sagittal) direction. Females are affected much more commonly than males. This condition occurs in the presence of an osseous (bone), cartilaginous or fibrous septum in the central portion of the spinal canal which then produces a complete or incomplete sagittal division of the spinal cord into two hemicords. When the split does not reunite distally to the spur, the condition is referred to as a diplomyelia, or true duplication of the spinal cord.

Till date about 18 cases of Spondylocostal dysostosis have been reported in literature.

Congenital vertebral anomalies are a collection of malformations of the spine. Most around 85% are not clinically significant, but they can cause compression of the spinal cord by deforming the vertebral canal or causing instability. This condition occurs in the womb. Congenital vertebral anomalies include alterations of the shape and number of vertebrae.

Spondylocostal dysostosis is a rare, heritable axial skeleton growth disorder. It is characterized by widespread and sometimes severe malformations of the vertebral column and ribs, shortened thorax, and moderate to severe scoliosis and kyphosis. Individuals with Jarcho-Levin typically appear to have a short trunk and neck, with arms appearing relatively long in comparison, and a slightly protuberant abdomen. Severely affected individuals may have life-threatening pulmonary complications due to deformities of the thorax. The syndrome was first described by Saul Jarcho and Paul M. Levin at Johns Hopkins University in 1938.

Medical conditions include frequent ear infection, hearing loss, hypotonia, developmental problems, respiratory problems, eating difficulties, light sensitivity, and esophageal reflux.

Data on fertility and the development of secondary sex characteristics is relatively sparse. It has been reported that both male and female patients have had children. Males who have reproduced have all had the autosomal dominant form of the disorder; the fertility of those with the recessive variant is unknown.

Researchers have also reported abnormalities in the renal tract of affected patients. Hydronephrosis is a relatively common condition, and researchers have theorized that this may lead to urinary tract infections. In addition, a number of patients have suffered from cystic dysplasia of the kidney.

A number of other conditions are often associated with Robinow syndrome. About 15% of reported patients suffer from congenital heart defects. Though there is no clear pattern, the most common conditions include pulmonary stenosis and atresia. In addition, though intelligence is generally normal, around 15% of patients show developmental delays.

Robinow syndrome is an extremely rare genetic disorder characterized by short-limbed dwarfism, abnormalities in the head, face, and external genitalia, as well as vertebral segmentation. The disorder was first described in 1969 by human geneticist Meinhard Robinow, along with physicians Frederic N. Silverman and Hugo D. Smith, in the "American Journal of Diseases of Children". By 2002, over 100 cases had been documented and introduced into medical literature.

Two forms of the disorder exist, dominant and recessive, of which the former is more common. Patients with the dominant version often suffer moderately from the aforementioned symptoms. Recessive cases, on the other hand, are usually more physically marked, and individuals may exhibit more skeletal abnormalities. The recessive form is particularly frequent in Turkey. However, this can likely be explained by a common ancestor, as these patients' families can be traced to a single town in Eastern Turkey. Clusters of the autosomal recessive form have also been documented in Oman and Czechoslovakia.

The syndrome is also known as Robinow-Silverman-Smith syndrome, Robinow dwarfism, fetal face, fetal face syndrome, fetal facies syndrome, acral dysostosis with facial and genital abnormalities, or mesomelic dwarfism-small genitalia syndrome. The recessive form was previously known as Covesdem syndrome.

Splenogonadal fusion is a rare congenital malformation that results from an abnormal connection between the primitive spleen and gonad during gestation. A portion of the splenic tissue then descends with the gonad. Splenogonadal fusion has been classified into two types: continuous, where there remains a connection between the main spleen and gonad; and discontinuous, where ectopic splenic tissue is attached to the gonad, but there is no connection to the orthotopic spleen. Patients with continuous splenogonadal fusion frequently have additional congenital abnormalities, most commonly cryptorchidism.

The anomaly was first described in 1883 by Bostroem. Since then more than 150 cases of splenogonadal fusion have been documented. The condition is considered benign. A few cases of testicular neoplasm have been reported in association with splenogonadal fusion. The reported cases have occurred in patients with a history of cryptorchidism, which is associated with an elevated risk of neoplasm.

Splenogonadal fusion occurs with a male-to-female ratio of 16:1, and is seen nearly exclusively on the left side. The condition remains a diagnostic challenge, but preoperative consideration of the diagnosis may help avoid unnecessary orchiectomy. On scrotal ultrasound, ectopic splenic tissue may appear as an encapsulated homogeneous extratesticular mass, isoechoic with the normal testis. Subtle hypoechoic nodules may be present in the mass. The presence of splenic tissue may be confirmed with a technetium-99m sulfur colloid scan.

Surgery

Surgical intervention is warranted in patients who present with new onset neurological signs and symptoms or have a history of progressive neurological manifestations which can be related to this abnormality. The surgical procedure required for the effective treatment of diastematomyelia includes decompression (surgery) of neural elements and removal of bony spur. This may be accomplished with or without resection and repair of the duplicated dural sacs. Resection and repair of the duplicated dural sacs is preferred since the dural abnormality may partly contribute to the "tethering" process responsible for the symptoms of this condition.

Post-myelographic CT scanning provides individualized detailed maps that enable surgical treatment of cervical diastematomyelia, first performed in 1983.

Observation

Asymptomatic patients do not require surgical treatment. These patients should have regular neurological examinations since it is known that the condition can deteriorate. If any progression is identified, then a resection should be performed.

Tethered spinal cord can be caused by various conditions but the main cause is when tissue attachments limit the movement of the spinal cord in the spinal column which causes abnormal stretching of the cord. The tethered spinal cord syndrome is correlated with having the causes:

- Spina bifida

- Occulta

- Mylomeningocele

- Meningocele

- History of spinal trauma

- History of spinal surgery

- Tumor(s) in the spinal column

- Thickened and/or tight filum terminale

- Lipoma(s) in the spinal column

- Dermal Sinus Tract (congenital deformity)

- Diastematomyelia (split spinal cord)

Tethered spinal cord is a disorder and not a mechanism so it does not spread to other people and there are no measures that can be done to prevent it beforehand. The only preventative measure that is successful is to surgically untether the spinal cord though there might already be irreversible damage.

The occurrence of ectopia cordis is 8 per million births. It is typically classified according to location of the ectopic heart, which includes:

- Cervical

- Thoracic

- Thoracoabdominal

- Abdominal

Thoracic and thoraco-abdominal ectopia cordis constitute the vast majority of known cases.

Many vertebrates, especially reptiles, have cervical ribs as a normal part of their anatomy rather than a pathological condition. Some sauropods had exceptionally long cervical ribs; those of "Mamenchisaurus hochuanensis" were nearly 4 meters long.

In birds, the cervical ribs are small and completely fused to the vertebrae.

In mammals the ventral parts of the transverse processes of the cervical vertebrae are the fused-on cervical ribs.

Recent studies have also found a high percent of cervical ribs in woolly mammoths. It is believed that the decline in mammoth numbers may have forced inbreeding within the species which in turn has increased the number of mammoths being born with cervical ribs. Cervical ribs have been connected with leukaemia in human children, so it has given scientists new evidence to believe that the mammoth's extinction was attributed to the condition.

TBS is an autosomal dominant involving the a mutation of the gene SALL1, which encodes a transcriptional repressor which interacts with TRF1/PIN2 and localizes to pericentromeric heterochromatin. The clinical features of TBS overlap with VATER and VACTERL associations, oculo-auriculo-vertebral (OAV) spectrum, branchio-oto-renal (BOR) syndrome, and Fanconi anemia and other 'anus-hand-ear' syndromes.

Although some symptoms can be life-threatening, many people diagnosed with Townes-Brocks Syndrome live a normal lifespan.

In tethered spinal cord cases Spina bifida can be accompanied by tethering of the spinal cord but in rare cases with Spina bifida Occulta. Tethering of the spinal cord tends to occur in the cases of Spina bifida with mylomeningocele. In a normal person the spine grows faster than the spinal cord during development which causes the end of the spinal cord to appear to rise relative to the bony spine next to it. By the time of birth the spinal cord is located between L1 and L2. In a baby with Spina bifida the spinal cord is still attached to the skin around it preventing it from rising properly. This occurs because the spinal cord in a child with Spina bifida is low lying and tethered at the bottom. At the time of birth the mylomeningocele is separated from the skin but the spinal cord is still stuck in the same place. As the child begins to grow the spinal cord remains in the same place becoming stretched out causing the tight cord and the tethering at the end. With this type of tethering there is an interference with the blood supply to the nerves and body which can then cause the deterioration of the body causing orthopedic, neurological, and urological problems. With milder forms of Spina bifida such as Occulta, may be related to the degree of strain on the cord which can become worse with physical activity, injury, pregnancy, bone spurs, or spinal stenosis. The tethered cord in this case might not be diagnosed until adulthood when it worsens and can still cause neurological, orthopedic, and urological dysfunctions.

Radioulnar synostosis is one of the more common failures of separation of parts of the upper limb. There are two general types: one is characterized by fusion of the radius and ulna at their proximal borders and the other is fused distal to the proximal radial epiphysis. Most cases are sporadic, congenital (due to a defect in longitudinal segmentation at the 7th week of development) and less often post-traumatic, bilateral in 60%, and more common in males. Familial cases in association with autosomal dominant transmission appear to be concentrated in certain geographic regions, such as Sicily.

The condition frequently is not noted until late childhood, as function may be normal, especially in unilateral cases. Increased wrist motion may compensate for the absent forearm motion. It has been suggested that individuals whose forearms are fixed in greater amounts of pronation (over 60 degrees) face more problems with function than those with around 20 degrees of fixation. Pain is generally not a problem, unless radial head dislocation should occur.

Most examples of radioulnar synostosis are isolated (non-syndromic). Syndromes that may be accompanied by radioulnar synostosis include X chromosome polyploidy (e.g., XXXY) and other chromosome disorders (e.g., 4p- syndrome, Williams syndrome), acrofacial dysostosis, Antley–Bixler syndrome, genitopatellar syndrome, Greig cephalopolysyndactyly syndrome, hereditary multiple osteochondromas (hereditary multiple exostoses), limb-body wall complex, and Nievergelt syndrome.

Craniosynostosis (from cranio, cranium; + syn, together; + ostosis relating to bone) is a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses by turning into bone (ossification). Craniosynostosis has following kinds: scaphocephaly, trigonocephaly, plagiocephaly, anterior plagiocephaly, posterior plagiocephaly, brachycephaly, oxycephaly, pansynostosis.

Cervical spinal stenosis is a bone disease involving the narrowing of the spinal canal at the level of the neck. It is frequently due to chronic degeneration, but may also be congenital. Treatment is frequently surgical.

Cervical spinal stenosis is one of the most common forms of spinal stenosis, along with lumbar spinal stenosis (which occurs at the level of the lower back instead of in the neck). Thoracic spinal stenosis, at the level of the mid-back, is much less common. Cervical spinal stenosis can be far more dangerous by compressing the spinal cord. Cervical canal stenosis may lead to serious symptoms such as major body weakness and paralysis. Such severe spinal stenosis symptoms are virtually absent in lumbar stenosis, however, as the spinal cord terminates at the top end of the adult lumbar spine, with only nerve roots (cauda equina) continuing further down. Cervical spinal stenosis is a condition involving narrowing of the spinal canal at the level of the neck. It is frequently due to chronic degeneration, but may also be congenital or traumatic. Treatment frequently is surgical.

A cervical rib in humans is an extra rib which arises from the seventh cervical vertebra. Sometimes known as "neck ribs", their presence is a congenital abnormality located above the normal first rib. A cervical rib is estimated to occur in 0.2% (1 in 500 people) to 0.5% of the population. People may have a cervical rib on the right, left or both sides.

Most cases of cervical ribs are not clinically relevant and do not have symptoms; cervical ribs are generally discovered incidentally. However, they vary widely in size and shape, and in rare cases, they may cause problems such as contributing to thoracic outlet syndrome, because of pressure on the nerves that may be caused by the presence of the rib.

A cervical rib represents a persistent ossification of the C7 lateral costal element. During early development, this ossified costal element typically becomes re-absorbed. Failure of this process results in a variably elongated transverse process or complete rib that can be anteriorly fused with the T1 first rib below.

On imaging, cervical ribs can be distinguished because their transverse processes are directed inferolaterally, whereas those of the adjacent thoracic spine are directed anterolaterally.

Anterolisthesis location includes which vertebrae are involved, and may also specify which parts of the vertebrae are affected.

"Isthmic" anterolisthesis is where there is a defect in the pars interarticularis. It is the most common form of spondylolisthesis; also called spondylolytic spondylolisthesis, it occurs with a reported prevalence of 5–7 percent in the US population. A slip or fracture of the intravertebral joint is usually acquired between the ages of 6 and 16 years, but remains unnoticed until adulthood. Roughly 90 percent of these isthmic slips are low-grade (less than 50 percent slip) and 10 percent are high-grade (greater than 50 percent slip). It is divided into three subtypes:

- A: pars fatigue fracture

- B: pars elongation due to multiple healed stress effects

- C: pars acute fracture