About Coffin-Siris Syndrome

BAF complex figure, showing that the genetic variants on genes related to the BAF pathway can cause Coffin-Siris syndrome.
Coffin-Siris syndrome is a rare genetic disorder characterized by developmental delays and underdeveloped fifth toenails or fingernails.

Genetic variants that occur in a group of genes related to the BAF pathway cause the syndrome by disturbing the regulation of gene expression during development.

Prevalence / Onset

Map background with the silhouette of a baby and words saying "There are more than 200 confirmed cases of Coffin-Siris syndrome worldwide."


Coffin-Siris syndrome is very rare; there are ~200 confirmed cases of Coffin-Siris syndrome worldwide.


Infants with Coffin-Siris syndrome are usually born with several signs, such as coarse facial features and underdeveloped fifth fingers or toes. Their developmental delays become increasingly apparent after birth.


Six symptoms of Coffin-Siris syndrome: Mild to severe intellectual disability, Abnormalities of the fifth fingers or toes, Delayed development of speech and motor skills, Coarse facial features, Excess hair on face and body, Sparse scalp hair

Inheritance Pattern

A family tree showing the autosomal dominant inheritance pattern of Coffin-Siris syndrome
Coffin-Siris syndrome inheritance is in an autosomal dominant pattern.
However, many cases are reported as related to new (de novo) genetic variants.


The diagnosis of Coffin-Siris syndrome is mostly based on a thorough clinical evaluation and characteristic physical findings.

Characteristic physical findings include:

  • Underdeveloped fifth finger or toe
  • Developmental and/or cognitive delays
  • Facial features such as a wide mouth and broad nose

However, recent studies have shown that an underdeveloped fifth finger or toe is not a mandatory finding. Genetic testing may be used to find related genetic variants and to confirm the diagnosis.

To learn more about detailed diagnosis story of a girl with Coffin-Siris syndrome, read Diagnosis story of a girl diagnosed with Coffin-Siris syndrome.


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  2. Therapy
  • Occupational, physical, and speech therapy may help people with Coffin-Siris syndrome.
  • A team of medical professionals who can plan tailored treatment for each individual is needed.
    The team can include developmental pediatricians, orthopedists, cardiologists, geneticists, and physical therapists.

    Upon severity, surgical repair of craniofacial, skeletal, cardiac, or other abnormalities may be required.


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  2. Avoid Intense Activities
    Intense activities such as weightlifting or contact sports can increase blood pressure, imposing extra burden to the aorta. Consult with your doctor to see if certain exercises are right for you.

Provide Support
For adolescents, appearance has a significant psychological impact. Contact lenses, orthosis for scoliosis, and dental work for teeth can help.

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