What Is the Life Expectancy of Someone With Coffin-Siris Syndrome?

Medically Reviewed on 1/30/2023

Person holding a newborn baby's hand
Life expectancy for people with Coffin-Siris syndrome (CSS) varies, depending on the severity of the illness.

Most people with Coffin-Siris syndrome (CSS) live relatively long lives. The lifespan of affected individuals varies widely depending on the person’s level of physical and mental development and the severity of the illness. Medical care increases the quality of life and lifetime of people with CSS.

What is Coffin-Siris syndrome?

  • Coffin-Siris syndrome (CSS) is a rare hereditary condition noticeable from birth (congenital).
  • Women are more affected than men, and only 200 cases have been reported in the medical literature.
  • CSS has an impact on several systems of the body. Even though there are many signs and symptoms of developmental disability, abnormalities of the fifth (pinky) fingers or toes and distinctive facial features are trademarks of this disorder.

What are the causes of Coffin-Siris syndrome?

Coffin-Siris syndrome (CSS) is caused by variations (also known as mutations) in one or more genes. Variations in the ARID1B gene are the most prevalent known cause of the disease.

  • Mutations in the SOX11, SMARCB1, SMARCB2, or ARID1A genes may cause the condition.
  • A minimal number of instances have also been linked to variations in a few other genes (mentioned below). In some of these cases, it is unclear whether the disorder under consideration is CSS or a related but distinct disorder. The genetic cause of CSS is not always known.
  • The above-mentioned genes play a role in regulating the function (expression) of other genes. The genes ARID1A, ARID1B, SMARCA4, SMARCB1, and SMARCE1, as well as some of the genes involved in rare cases of CSS, offer instructions for constructing specific components (subunits) of numerous switch/sucrose nonfermentable (SWI/SNF) protein complexes. To regulate gene expression, SWI/SNF complexes employ chromatin remodeling.
  • SWI/SNF complexes are engaged in various functions, such as repairing damaged DNA, replicating (copying) DNA, and regulating the development, division, and maturation (differentiation) of cells. All these activities are performed through chromatin remodeling.
  • It is unknown how mutations in the genes for ARID1A, ARID1B, SMARCA4, SMARCB1, or SMARCE1 affect SWI/SNF complexes; however, it is thought that these mutations produce aberrant chromatin remodeling. The alteration of this mechanism, which affects the operation of numerous genes and interferes with several cellular processes, may cause various signs and symptoms of CSS.

What are the signs and symptoms of Coffin-Siris syndrome?

Infancy: Even though many congenital problems may not be clinically evident at birth, those who have Coffin-Siris syndrome (CSS) may exhibit the following congenital disorders:

  • Hypoplasia of the fifth toe's nails or digits: Most people have at least one hypoplastic nail and brachydactyly on the fifth digit. It should be emphasized that some people with a molecularly verified diagnosis of CSS have minimal or no involvement of the fifth digit.
  • Dysmorphic facial features: The distinctive facial features may not be visible until later in childhood because facial characteristics usually become coarser with age.
  • There are frequent reports of hirsutism.
  • Malformations affecting the central nervous system, heart and genitourinary system.
  • Other findings appearing in infancy that may be the first indication of CSS:


  • Developmental delays: The developmental/cognitive delay typically becomes evident when missed developmental milestones are observed and/or formal cognitive testing is carried out.
  • Brain/central nervous system issues
  • Facial features:
    • Coarse facies (coarse facial features)
    • Short nose
    • Anteverted nares
    • Thick eyebrows
    • Broad nasal tip
    • Wide mouth
    • Prominent eyelashes
    • Flat nasal bridge
    • Wide nasal base
    • Thin vermilion of the upper lip
    • Broad philtrum
    • Thick vermilion of the lower lip
  • Musculoskeletal features
    • Small nails on the fifth finger or toe
    • Scoliosis
    • Delayed bone age
    • Clinodactyly
    • Hernias
    • Joint laxity

What is the treatment for the Coffin-Siris syndrome?

Coffin-Siris syndrome is treated according to the unique characteristics of each person. To organize such a treatment, a group of medical professionals may need to collaborate, and they may need to carefully and deliberately prepare treatment protocols for the affected child. These specialists may include pediatricians, orthopedists (doctors who specialize in disorders of the skeleton, joints, muscles, and related tissues), cardiologists (doctors who diagnose and treat heart abnormalities), digestive abnormality specialists, physical therapists, geneticists, and/or other medical professionals.

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Medically Reviewed on 1/30/2023