Short answer · Medically reviewed summary · Last updated: 2026-05-08
Freeman Sheldon Syndrome (FSS), also known as distal arthrogryposis type 2A, is a rare genetic disorder primarily caused by mutations in the MYH3 gene. This condition follows an autosomal dominant inheritance pattern, meaning a single altered copy of the gene is sufficient to cause the syndrome, though it can also occur as a spontaneous (de novo) mutation. What causes Freeman Sheldon Syndrome? The primary cause of Freeman Sheldon Syndrome is a mutation in the MYH3 gene, which provides instructions for making a protein called embryonic myosin heavy chain.
1 people with Freeman Sheldon Syndrome have shared their first-person experience on this question at DiseaseMaps.
Which are the causes of Freeman Sheldon Syndrome?
Causes of Freeman Sheldon Syndrome explained: genetic and environmental factors, reviewed against medical sources, plus patient perspectives.
Freeman Sheldon Syndrome (FSS), also known as distal arthrogryposis type 2A, is a rare genetic disorder primarily caused by mutations in the MYH3 gene. This condition follows an autosomal dominant inheritance pattern, meaning a single altered copy of the gene is sufficient to cause the syndrome, though it can also occur as a spontaneous (de novo) mutation.
What causes Freeman Sheldon Syndrome?
The primary cause of Freeman Sheldon Syndrome is a mutation in the MYH3 gene, which provides instructions for making a protein called embryonic myosin heavy chain. This protein is essential for the proper development and contraction of muscles before birth. When this gene is mutated, it interferes with normal muscle fiber formation, leading to the characteristic joint contractures and facial features associated with Freeman Sheldon Syndrome.
Is Freeman Sheldon Syndrome hereditary?
Yes, Freeman Sheldon Syndrome is typically inherited in an autosomal dominant manner. However, it is important to distinguish between inherited and spontaneous cases:
- Familial inheritance: The mutation is passed from an affected parent to their child.
- De novo mutations: In many documented cases, the mutation occurs spontaneously in the egg or sperm cell, meaning neither parent carries the genetic change.
Are there environmental or external triggers?
There are no known environmental triggers, infectious causes, or autoimmune mechanisms linked to the development of Freeman Sheldon Syndrome. Because it is a primary genetic condition, it cannot be caused by maternal diet, medications, or exposures during pregnancy. The etiology of Freeman Sheldon Syndrome is strictly rooted in the molecular dysfunction of the MYH3 protein.
What does current research suggest?
Researchers are actively studying how different variants of the MYH3 gene lead to the varying severity of Freeman Sheldon Syndrome. While the core genetic cause is well-established, ongoing studies focus on how these specific protein changes impact long-term muscle function and bone development. With 32 individuals currently sharing their experiences on DiseaseMaps.org, community-driven data continues to help clinicians better understand the lived experience of those affected by this condition.
Next steps
- Consult with a clinical geneticist to discuss genetic testing and family planning options.
- Connect with the 32 members of the Freeman Sheldon Syndrome community on DiseaseMaps.org to share experiences.
- Speak with a pediatric orthopedist or a specialist in congenital muscle disorders for personalized care planning.
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 Syndrome.
Posted Oct 5, 2017 by Jrdtmk 1500
