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Antley-Bixler syndrome is an uncommon genetic illness characterised by skull, face, and limb bone deformities. It is caused by mutations in the FGFR2 gene, which codes for a protein known as fibroblast growth factor receptor 2. During foetal development, this protein is essential for the development of bones and other tissues.

Antley–Bixler Syndrome :‎ [MEDNOTES+MINDMAP]

Definition:

  • A rare genetic disorder characterized by abnormal development of the bones in the face and skull, and abnormalities in the endocrine system

Epidemiology:

  • Prevalence is unknown, but estimated to be 1 in 250,000 live births
  • Occurs more commonly in males

Natural history:

  • Symptoms may appear at birth or in early infancy
  • Symptoms can include craniofacial abnormalities, skeletal abnormalities, and endocrine abnormalities
  • Severity of symptoms can vary widely
  • May have developmental delays or intellectual disability
  • Can lead to complications such as respiratory problems, hearing loss, and vision loss

Classification/Types/Stages:

  • Types can vary widely, as the genetic mutations that cause Antley–Bixler Syndrome are diverse
  • Stages of the syndrome may be classified based on the severity of craniofacial abnormalities and other symptoms. For example:
    • Stage 1: Mild craniofacial abnormalities, mild endocrine abnormalities
    • Stage 2: Moderate craniofacial abnormalities, moderate endocrine abnormalities
    • Stage 3: Severe craniofacial abnormalities, severe endocrine abnormalities
  • Risk Factors

    • Genetic mutations
    • Unknown environmental factors
  • Etiology/Causes

    • Mutations in the following genes:
      • FGFR2
      • FGFR3
      • TWIST1
    • These mutations lead to abnormal development and function of the bones, particularly the skull and limbs.
  • Signs

    • Craniosynostosis (fused cranial sutures)
    • Midface hypoplasia (underdeveloped midface)
    • Choanal atresia (narrowed or blocked nasal passages)
    • Malformed or absent ears
    • Malformed or absent thumbs
    • Short stature
    • Joint contractures (limited movement in joints)
  • Symptoms

    • Breathing difficulties due to choanal atresia
    • Hearing loss due to malformed or absent ears
    • Developmental delays
    • Chronic pain due to joint contractures
  • Pathology/Pathogenesis

    • Abnormal development and function of the skull, face, and limbs due to mutations in FGFR2, FGFR3, and TWIST1 genes.
    • This leads to the characteristic physical features of Antley-Bixler Syndrome, as well as potential complications such as breathing difficulties and developmental delays.
  • Diagnosis
    • Antley–Bixler Syndrome is a rare genetic disorder that affects the development of the bones, head, and facial features.
    • It is diagnosed based on physical examination and imaging tests, such as X-rays, CT scans, and MRI scans.
    • Genetic testing can also be done to confirm the diagnosis.
  • Tests Required
    • X-rays: to assess the development and abnormalities of the bones
    • CT scans: to get a detailed view of the bones and other tissues
    • MRI scans: to get a detailed view of the brain and other organs
    • Genetic testing: to confirm the diagnosis and determine the specific genetic mutation causing the condition
  • Associated with
    • Antley–Bixler Syndrome is strongly associated with mutations in the FGFR2 gene, which plays a crucial role in the development of the bones and other tissues.
    • It is also associated with other genetic mutations that can cause similar features and symptoms.
  • Similar diseases/syndromes
    • Apert Syndrome: a genetic disorder that affects the development of the bones, head, and face
    • Crouzon Syndrome: a genetic disorder that affects the development of the bones in the skull
    • Pfeiffer Syndrome: a genetic disorder that affects the development of the bones in the skull and face
  • Treatment
    • Antley–Bixler Syndrome has no cure, and treatment is focused on managing the symptoms and complications.
    • Treatment may include surgeries to correct abnormalities in the bones, head, and face, as well as medications to manage pain and other symptoms.
    • Physical therapy and occupational therapy can also be helpful in improving mobility and function.
 

Dr. Arin Nandi

Passionate About Medical Science & Helping Future Doctors Achieve Top Ranks In Medical Exams. He is professionally a dentist as well as a public health expert from JIPMER working in govt.health department
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