What Is Freeman Sheldon Syndrome?

Freeman-Sheldon Syndrome (FSS) is a rare genetic condition that mainly affects the muscles of the face and skull (craniofacial muscles) and the joints of the hands and feet.2

FSS was named and verified by Prof. Frederick Burian in 1962 after findings of a similar disorder known as Sheldon-Hall syndrome were published by Mr Ernest Arthur Freeman and Dr John Howard Sheldon in 1938.2 There are three subtypes of FSS based on the symptoms and the extensiveness of the condition.2 Treatment is available utilising a multi-disciplinary approach to manage the condition as well as the psychological impact.1

Other names of FSS: 

  • Freeman-Burian Syndrome 
  • FBS
  • Craniocarpotarsal dysplasia
  • Craniocarpotarsal dysplasia
  • DA2
  • Distal arthrogryposis 2A
  • FSS
  • Whistling face syndrome 
  • Whistling face-windmill vane hand syndrome.2


  • Classic: Freeman-Sheldon syndrome type 1 
  • Craniofacial: Freeman-Sheldon type 2
  • Mixed: Freeman-Sheldon syndrome type 3 (upper or lower extremities) 

Causes of FSS: 

Genetic mutation:

A mutation in the embryonic myosin heavy chain (MYH3) gene, which is responsible for muscle development in the embryo. 2

Myosin helps to convert the cell’s chemical energy, adenosine triphosphate (ATP), to mechanical energy for muscles to contract and generate movement.

In FSS, the altered genetic make-up of the MYH3 gene results in impaired muscle development in the embryo as the ATP needed for muscles to contract (tense) cannot attach to the myosin and be converted to the mechanical energy needed. Further studies are required to establish a link between environmental and parenteral factors such as exposure to illnesses, toxins, drugs or harsh substances. 2

The pattern of inheritance:

FSS is a genetic disorder that is inherited. Following an autosomal dominant pattern of inheritance, a copy of the mutated gene has to be present in each cell for the child to be born with FSS.

A phenomenon known as ‘germline mosaicism’ occurs when the parent has the mutated gene variant in most, if not all, of their sperm or egg cells and is extremely rare in FSS. 

Symptoms and clinical features

There are very distinct features that are characteristic of FSS: 

Facial features

  • Microstomia (smallmouth) 
  • H or V-shaped dimpling of the chin 
  • Nasal abnormalities leading to breathing difficulties

Muscular and skeletal issues

  • Joint contractures 
  • Clubfoot 
  • Muscle weakness 

Speech and swallowing difficulties 

Other associated features (varies from person to person)


There are no specific diagnostic tests for FSS as it has distinct facial features.

Clinical evaluation

A clinician would look for specific facial features such as a small mouth (microstomia), whistling face appearance (pursed lips), “H” or “V” shaped chin and a defined crease from the nostril to the corners of the mouth.2

Genetic testing

This is possible as it is caused by mutations in the MYH3 gene. This gene is responsible for making myosin-3, a protein which, amongst other proteins, is used to make up muscle fibres. 3

Differential diagnosis (distinguishing FSS from other conditions)

There are other disorders with similar symptoms. Other disorders such as distal arthrogryposis (DA) and arthrogryposis multiplex congenital (AMC) also present with hand, foot, mouth and facial defects. 2

Treatment and management

Due to the nature of the condition, a multi-disciplinary approach is taken since many parts of the body are affected. The team could consist of craniofacial surgeons, neurosurgeons, ophthalmologists, ear, nose and throat (ENT) surgeons, audiologists, dentists and orthodontists, geneticists, psychologists and speech and language therapists (SALT).1

Craniofacial surgeons may carry out surgery to either reshape the frontal bone or increase eyelid opening. Plastic surgery is performed to increase the size of the mouth.

Other interventions:

  1. Orthopaedic surgery to correct hand and foot malformations
  2. Physical therapy alongside surgery to improve hand function and walking ability
  3. Speech therapy
  4. Adaptive Devices and Assistive Technology
    1. Oral device used for a few hours each day 
    2. Additional assistive devices to support those with lower extremity contractures i.e. foot malformation. 4

Supportive care and counselling

In addition to physical symptoms, the psychological well-being of an individual with FSS will be impacted, as well as family and friends.

A person diagnosed with FSS may struggle with:

  • Self-image
  • Feelings of inadequacy
  • Anger and rage
  • Post-traumatic stress disorder (PTSD)
  • Depression
  • Social anxiety
  • Substance abuse
  • Maladaptive sexual behaviours

Some groups and organisations help families and children of those affected by craniofacial disorders, limb malformations and mental wellbeing.1

Headlines - A craniofacial support group in the UK for families of children and young people affected by craniofacial disorders.1

Changing Faces - Offers help and support to anyone living with a condition that affects their appearance.1

You can visit their website at http://www.changingfaces.org.uk/ or call their helpline on 0845 4500 275

STEPS - A UK-based charity that supports people with lower limb abnormalities.1

MIND - Mental Health Charity.1

FSS has varying levels of severity, and not all people will have limb malformations however, features such as the H or V-shaped chin defects are typical features. Quality of life is improved with craniofacial surgery in the early stages and comprehensive physiotherapy.

If people with spinal curvatures develop abnormalities, this can significantly impact their pulmonary and gastrointestinal function as well as life-long psychological implications.


  • FSS is a rare genetic disorder caused by a genetic mutation in the MYH3 gene. Treatment is available in the form of surgery, physiotherapy, and additional care and support from various charities
  • Clinical features include a small mouth, H or V-shaped chin and joint contractures.
  • Craniofacial surgery and physiotherapy are the main treatment methods with a multi-disciplinary approach.
  • To prevent complications, early interventions are key to improving the person’s functional and occupational status. 
  • With limited study data, research and discourse on the frequency of FSS, there is little information on other therapeutic approaches besides surgery and assistive devices. 


What is the life expectancy of a person living with FSS? 

  • In most cases, people who survive live to have an average life expectancy. 7

What is FSS malignant hyperthermia? 

  • People with FSS are predisposed to experiencing malignant hyperthermia due to the abnormal proteins in their muscle cells.6
  • The anaesthesia used in surgical procedures such as dental extractions, spinal contractions and corrections of skeletal deformities can cause malignant hyperthermia, arrhythmias and difficulties with airway intubation.6
  • Signs of malignant hyperthermia include:
    • Unexplained increase in heart rate 
    • Increase in carbon dioxide production in the body 
    • Rapid breathing 
    • Muscle rigidity 
    • A rapid increase in body temperature 6


  1. GOSH Hospital site [Internet]. [cited 2023 Sep 3]. Freeman-Sheldon syndrome. Available from: https://www.gosh.nhs.uk/conditions-and-treatments/conditions-we-treat/freeman-sheldon-syndrome/ 
  2. Freeman sheldon syndrome - symptoms, causes, treatment | nord [Internet]. [cited 2023 Sep 3]. Available from: https://rarediseases.org/rare-diseases/freeman-sheldon-syndrome/ 
  3. Freeman-sheldon syndrome: medlineplus genetics [Internet]. [cited 2023 Sep 3]. Available from: https://medlineplus.gov/genetics/condition/freeman-sheldon-syndrome/ 
  4. Dell Children’s Craniofacial Team of Texas [Internet]. [cited 2023 Sep 3]. Freeman–sheldon syndrome(Fss). Available from: https://www.craniofacialteamtexas.com/craniofacial-conditions-we-treat/syndromes-craniofacial-deformities/freeman-sheldon-syndrome-fss/
  5. Poling MI, Dufresne CR, Chamberlain RL. Freeman-Burian syndrome. Orphanet J Rare Dis [Internet]. 2019 Jan 10 [cited 2023 Sep 3];14:14. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6327538/
  6. Cleveland Clinic [Internet]. [cited 2023 Sep 6]. Malignant hyperthermia: what it is, symptoms & treatment. Available from: https://my.clevelandclinic.org/health/diseases/17945-malignant-hyperthermia
  7. Salati SA, Hussain M. Freeman-sheldon syndrome. APSP J Case Rep [Internet]. 2013 Jan 1 [cited 2023 Sep 6];4(1):7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3525289/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Tinetariro Rejoice Chimedza

Master's degree, Pharmacy, University of Bath

Rejoice is a newly qualified Pharmacist working in the hospital sector. Completed her foundation trainee year working for the second biggest healthcare provider in the UK. She writes weekly articles on a variety of health topics and is passionate about making information accessible and promote understanding.

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