What is Freeman Sheldon Syndrome

Freeman Sheldon Syndrome, also known as distal arthrogryposis type 2A, is a rare genetic disorder characterized primarily by distinctive facial features and joint contractures present at birth. This condition affects the development of the musculoskeletal system and is typically caused by mutations in the MYH3 gene.

What are the primary characteristics of Freeman Sheldon Syndrome?

Freeman Sheldon Syndrome is a type of distal arthrogryposis, meaning it primarily affects the hands and feet. The most recognizable features include a small mouth (microstomia), a high-arched palate, and a "whistling" appearance of the lips. Individuals with Freeman Sheldon Syndrome often experience joint contractures, where joints are fixed in a bent or extended position, which can impact mobility and daily activities.

What causes Freeman Sheldon Syndrome?

The underlying mechanism involves mutations in the MYH3 gene, which provides instructions for making a protein essential for muscle contraction. In most cases, Freeman Sheldon Syndrome is inherited in an autosomal dominant pattern, meaning a single copy of the mutated gene from one parent is sufficient to cause the condition. However, it can also occur as a *de novo* (new) mutation in individuals with no family history of the disorder.

How is Freeman Sheldon Syndrome classified and how common is it?

Freeman Sheldon Syndrome is considered an extremely rare condition, with fewer than 100 cases reported in medical literature worldwide, though it is likely underdiagnosed. It belongs to the broader category of distal arthrogryposis, specifically classified as type 2A. Key clinical features that differentiate Freeman Sheldon Syndrome from other similar disorders include:

• Profound microstomia (small mouth opening).


• Characteristic "H-shaped" dimpling of the chin.


• Ulnar deviation of the fingers (fingers angled toward the pinky).


• Clubfoot (talipes equinovarus) present at birth.

Who is affected by this condition?

Freeman Sheldon Syndrome affects both males and females equally, with symptoms present at birth (congenital). Because there are 32 individuals with Freeman Sheldon Syndrome within the DiseaseMaps community, we know that patients and their families often benefit greatly from shared experiences regarding surgical interventions and physical therapy management.

Next steps

• Consult with a clinical geneticist to confirm the diagnosis through MYH3 gene testing.


• Coordinate care with an orthopedic specialist and a craniofacial team.


• Join the DiseaseMaps community to connect with other families navigating Freeman Sheldon Syndrome.

Medical disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Freeman-Sheldon syndrome.


• Orphanet: Distal arthrogryposis type 2A.


• OMIM (Online Mendelian Inheritance in Man): #193700.


• Freeman-Sheldon Parent Support Group resources.