Which are the causes of Multiple epiphyseal dysplasia?

Multiple epiphyseal dysplasia (MED) is a rare genetic skeletal disorder primarily caused by mutations in genes responsible for the development of cartilage and bone. These genetic changes disrupt the normal maturation of the epiphyses—the rounded ends of long bones—leading to joint pain, stiffness, and early-onset osteoarthritis.

What causes Multiple epiphyseal dysplasia at the genetic level?

Multiple epiphyseal dysplasia is fundamentally a disorder of the skeletal system’s connective tissue. In the majority of cases, the condition is caused by pathogenic variants (mutations) in specific genes that provide instructions for making proteins essential to cartilage structure. Think of cartilage as the "scaffolding" of your growing bones; when the genetic blueprint for this scaffolding is flawed, the bones cannot grow or align correctly, leading to the characteristic findings of Multiple epiphyseal dysplasia.

Which specific genes are involved in Multiple epiphyseal dysplasia?

Research has identified several genes associated with the development of Multiple epiphyseal dysplasia. The pattern of inheritance varies depending on the specific gene involved, which is why genetic counseling is a critical component of care for families affected by this condition. The following genes are known to be linked to the disorder:

• COMP (Cartilage Oligomeric Matrix Protein): Mutations in this gene are the most common cause of the autosomal dominant form of Multiple epiphyseal dysplasia.


• COL9A1, COL9A2, and COL9A3: These genes provide instructions for making components of type IX collagen, which is vital for cartilage integrity.


• MATN3 (Matrilin-3): Mutations here also typically follow an autosomal dominant inheritance pattern.


• DTDST (SLC26A2): Mutations in this gene are associated with the recessive form of Multiple epiphyseal dysplasia, which is generally more severe.

Are there environmental or lifestyle triggers for Multiple epiphyseal dysplasia?

There are no known environmental, dietary, or infectious triggers that cause Multiple epiphyseal dysplasia. Because the condition is strictly genetic, it is present from the moment of conception. It is important for patients and caregivers to understand that nothing done during pregnancy or early childhood causes this condition to occur. While physical activity levels may influence the severity of joint symptoms (the "risk factors" for pain), they do not alter the underlying genetic cause of the disease.

Is the cause of Multiple epiphyseal dysplasia fully understood?

While we have identified the primary genetic drivers for many cases, the etiology of Multiple epiphyseal dysplasia is still an active area of research. Approximately 20% to 30% of individuals clinically diagnosed with Multiple epiphyseal dysplasia do not have a mutation in any of the currently known associated genes. This suggests that there are additional, as-yet-undiscovered genes that contribute to the development of the condition. Ongoing clinical research is focused on identifying these missing genetic links to improve diagnostic accuracy for the 89 members of the DiseaseMaps.org community and others worldwide.

Next steps

• Consult with a clinical geneticist to discuss genetic testing options and to determine the inheritance pattern within your family.


• Schedule an evaluation with a pediatric orthopedist or a rheumatologist to manage joint health and monitor for early-onset osteoarthritis.


• Join the DiseaseMaps.org community to connect with others who have Multiple epiphyseal dysplasia and share experiences regarding management strategies.


• Request a referral to a physical therapist who specializes in skeletal dysplasias to develop a low-impact exercise plan that supports joint mobility.

Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Multiple epiphyseal dysplasia.


• Orphanet: Multiple epiphyseal dysplasia, autosomal dominant.


• Online Mendelian Inheritance in Man (OMIM): Entry #132400 (Multiple Epiphyseal Dysplasia).


• Skeletal Dysplasia Management Consortium clinical guidelines.