Klippel-Feil Syndrome (KFS)

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Klippel-Feil syndrome (KFS) is a rare musculo-skeletal genetic disorder primarily characterised by the failure of spinal bones (vertebrae) in the neck (cervical) region of the spine to divide as they usually would during early fetal development (within the first 12 weeks of pregnancy). This results in any 2 or more of the 7 neck (cervical) vertebrae being fused together from birth (congenital).

Additional fusions or anomalies of vertebrae in the chest (thoracic) region of the spine or lower (lumber) spine may also be seen in KFS.

Types of KFS

KFS Type I is characterised by one large fusion of the bones in the neck (cervical vertebrae) and can include fusion into the bones of the upper back (thoracic vertebrae). Type II is characterised by multiple fusions of the vertebrae in the neck (rather than one large fusion) and can also include upper thoracic vertebrae. Type III on the other hand is characterised by fusion of vertebrae in the neck as well as the lower part of the spine (lower thoracic or lumbar vertebrae).

Signs and Symptoms

The most common signs of the condition are a short neck, low hairline at the back of the head and limited movement of the head and neck. Most people with the condition have one or two of these characteristic features.

While the problem with the spine is present from birth, the symptoms can become apparent at any age and vary widely. How mildly or severely someone is affected by the condition varies considerably, and as such mild cases may go undiagnosed until later in life when symptoms either worsen or first become apparent.

In addition to anomalies of the vertebrae, the condition can be associated with a wide range of other health problems affecting many different parts of the body. About 30% of people with KFS have other differences with their skeleton, such as unusual curvature of the spine (scoliosis), a mild birth defect of the spine (spina bifida occulta), one shoulder blade higher than the other (Sprengel deformity of the shoulder) and/or rib defects.

Approximately 25-50% of people have hearing loss. The condition can also be found with eye problems, head and face differences including facial asymmetry, an opening in the roof of the mouth (cleft palate), congenital heart defects, kidney and urinary tract problems, involuntary muscle movements including when one side of the body is moved, the other side wanting to do exactly the same (known as mirror movements), and sometimes the voice box (larynx) can be involved causing problems with speech. In some cases, neurological complications may result due to associated spinal cord injury.

Klippel-Feil anomaly can occur as part of other syndromes, including MURCS Association, Wildervanck syndrome and Goldenhar syndrome, as well as others.


KFS is thought to affect around 1 in 42,000 people and to occur in females more often than in males.

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KFS can be diagnosed by thorough clinical examination, medical history and medical imaging. Diagnostic imaging is most commonly done by X-rays but magnetic resonance imaging (MRI) and computed tomography (CT) may also be done to better visualise the vertebrae and determine exactly which vertebrae are fused and how.

As the condition can include other health issues, additional tests may also be carried out, such as hearing tests and ultrasound scans of the heart and kidneys.


Treatment for individuals with KFS aims to provide relief from any symptoms and supportive care. Treatment can range from modification of activities to extensive spinal surgery.  A variety of conservative measures can be helpful including cervical (neck) collars, traction, back braces, physiotherapy and various pain medications.

Genetics and inheritance

KFS can occur as an isolated anomaly or as part of another syndrome. In many cases there is no known family history of KFS and it is uncertain exactly how the condition has been inherited. However, it is known that KFS can be inherited as a dominant or recessive trait, and the condition has been associated with genetic alterations (mutations) in several genes.

There are 3 main genes known to be associated with KFS at the present time (2016). These are called GDF6, GDF3 and MEOX1. These genes are important for bone formation, particularly the vertebrae.

When KFS is caused by genetic alterations (mutations) in the GDF6 or GDF3 genes, it is inherited in an autosomal dominant pattern. This means that an alteration in just one copy of either the GDF6 or GDF3 genes is sufficient to cause the condition. Each child of an individual with dominant KFS has a 50% or 1 in 2 chance of inheriting the condition. This chance is the same whether the child is a girl or a boy.

When KFS is caused by genetic alterations (mutations) in the MEOX-1 gene, it is inherited in an autosomal recessive pattern. This means that alterations in both copies of the MEOX-1 gene are needed to cause the condition. Someone who has one altered copy and one working copy of the gene is an unaffected carrier of the condition. When both parents are carriers there is a 25% or 1 in 4 chance, for each child, of them inheriting KFS.

When Klippel-Feil anomaly is a feature of another condition, it is caused by genetic alterations in the genes involved in the other disorder.

Genetic services and testing

The availability of genetic testing, for different conditions and different genes, changes over time. Genetic Counselling may be of benefit to individuals with KFS and their families. This can be accessed through NHS genetic clinics http://www.geneticdisordersuk.org/parentsofaffectedchildren/managinghealthcare/specialistgeneticcentres

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