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Multiple epiphyseal dysplasia
MED causes changes in how joints form, leading to joint pain and early-onset osteoarthritis. It typically affects children and adults, impacting mobility and quality of life. The condition can be inherited in different ways.
Overview
Multiple epiphyseal dysplasia (MED) refers to a collection of genetic disorders that predominantly affect the cartilage and the ends of long bones, known as epiphyses [PMID:20301712]. These are crucial areas for bone growth and joint formation. The condition can lead to abnormalities in joint development, which may result in pain and stiffness, often becoming noticeable during childhood or adolescence. It is a relatively rare condition, estimated to affect approximately 1 in 10,000 individuals.
Over time, these joint changes can increase the risk of developing osteoarthritis at a younger age than typically expected. While MED primarily affects the skeletal system, its severity and specific symptoms can vary significantly among individuals, even within the same family.
Symptoms & clinical features
The symptoms of multiple epiphyseal dysplasia often become apparent during early childhood, typically between the ages of 2 and 10 years, but can sometimes emerge later [PMID:20301712]. Common signs include joint pain, especially in the hips and knees, which may worsen after physical activity. Affected individuals might also experience stiffness, particularly in the morning or after periods of rest.
Other symptoms can include a waddling gait, limited range of motion in the affected joints, and sometimes short stature, though this is usually mild. Some individuals may have mild bowing of the legs or other subtle skeletal changes. The specific joints affected and the severity of symptoms can differ widely, making diagnosis challenging in some cases.
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Affected organs
Multiple epiphyseal dysplasia primarily affects the skeletal system, specifically the joints and the epiphyses (ends of long bones). The cartilage that covers the ends of bones within joints is also commonly affected. The hips, knees, ankles, and shoulders are among the most frequently involved joints. In some forms of MED, the spine can also be affected, potentially leading to mild scoliosis or back pain.
Risks & severity
The severity of multiple epiphyseal dysplasia varies considerably, ranging from mild forms with minimal symptoms to more severe cases causing significant joint pain and mobility issues [PMID:20301712]. A common long-term risk associated with MED is the early development of osteoarthritis, particularly in the weight-bearing joints like the hips and knees. This can begin in early adulthood, potentially requiring joint replacement surgery at a younger age than is typical for age-related osteoarthritis.
While MED is a progressive condition, its progression rate differs between individuals. Age of onset for symptoms is typically in childhood, but the impact on daily life can increase with age as joint degeneration advances. The condition does not generally affect life expectancy.
Genetic causes
Multiple epiphyseal dysplasia is caused by genetic changes (pathogenic variants) in specific genes involved in the development and maintenance of cartilage and bone. The genes currently known to be associated with MED in our reference dataset include COL9A2, COMP, and MATN3.
The COMP gene provides instructions for making cartilage oligomeric matrix protein, which is essential for the structure and function of cartilage [PMID:27878893]. Pathogenic variants in COMP can disrupt this protein, leading to weakened cartilage. Similarly, COL9A2 produces a component of type IX collagen, a protein crucial for cartilage structure. MATN3 encodes matrilin 3, another protein vital for cartilage integrity and joint formation. When these genes do not function correctly due to a pathogenic variant, it can impair normal cartilage development, contributing to the symptoms of MED.
- COL9A2 collagen type IX alpha 2 chain
- COMP cartilage oligomeric matrix protein
- MATN3 matrilin 3
Inheritance pattern
Multiple epiphyseal dysplasia can be inherited in different ways. Some forms follow an autosomal dominant inheritance pattern, meaning only one copy of the altered gene in each cell is sufficient to cause the condition. In such cases, an affected individual has a 50% chance of passing the condition on to each child. Other forms follow an autosomal recessive inheritance pattern, where both copies of the gene must have a pathogenic variant for the condition to manifest. Individuals with one copy of the altered gene are known as carriers and typically do not show symptoms.
Understanding the specific inheritance pattern for a family is important for assessing risks for other family members. Genetic counselling can provide detailed information about the inheritance and implications for future generations.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
Diagnosis & testing
Diagnosing multiple epiphyseal dysplasia typically involves a combination of clinical evaluation, imaging studies, and genetic testing. X-rays of the joints, particularly the hips and knees, are often the first step, revealing characteristic changes in the epiphyses [PMID:20301712]. These changes can include flattened or irregular epiphyses.
If MED is suspected, referral to a clinical genetics service is often recommended. Genetic testing can confirm the diagnosis by identifying pathogenic variants in genes like COL9A2, COMP, or MATN3. This testing is often performed through the NHS Genomic Medicine Service, typically following an R-code pathway for skeletal dysplasias. A genetic counsellor can explain the testing process, potential results, and implications for the individual and their family.
Management & lifestyle
Management of multiple epiphyseal dysplasia focuses on symptom relief, preserving joint function, and preventing or delaying the onset of severe osteoarthritis. Treatment strategies are individualised based on the severity of symptoms and the specific joints affected. Non-surgical approaches often include physiotherapy to maintain joint mobility and strength, pain management with suitable medications, and lifestyle adjustments to reduce stress on joints.
For severe joint damage, particularly in the hips, surgical interventions like osteotomies (bone cutting and re-alignment) or joint replacement surgery may be considered. These decisions are made in consultation with orthopaedic specialists. Regular follow-up with healthcare professionals, including orthopaedic surgeons and physiotherapists, is an important part of ongoing care within the NHS framework.
UK care pathway
In the UK, individuals suspected of having a rare genetic condition like multiple epiphyseal dysplasia are typically referred to a clinical genetics service. This pathway often begins with a referral from a GP or specialist. The NHS Genomic Medicine Service provides access to advanced genomic testing, guided by specific R-codes for skeletal dysplasias, to help confirm a diagnosis. Genetic counsellors play a vital role, offering support and information about the condition, inheritance patterns, and implications for family planning.
Frequently asked questions
Will my children inherit Multiple Epiphyseal Dysplasia?
The chance of your children inheriting MED depends on its specific inheritance pattern in your family. If it's autosomal dominant, there's a 50% chance for each child. If it's autosomal recessive, both parents must be carriers for a 25% chance per child. Genetic counselling can provide personalised risk assessments.
Can diet or exercise help with MED symptoms?
While diet cannot cure MED, maintaining a healthy weight can reduce stress on your joints. Low-impact exercises, like swimming or cycling, are often recommended by physiotherapists to maintain joint mobility and muscle strength without aggravating pain. Always discuss exercise plans with your doctor or physiotherapist.
What is the long-term outlook for someone with MED?
The long-term outlook varies greatly depending on the severity of the condition. Many individuals lead full lives, though they may experience chronic joint pain and develop osteoarthritis earlier than others. Regular medical care and management can help minimise symptoms and maintain quality of life.
Is there a cure for Multiple Epiphyseal Dysplasia?
Currently, there is no cure for multiple epiphyseal dysplasia. Treatment focuses on managing symptoms, such as pain and stiffness, and preventing further joint damage. This often involves a combination of physiotherapy, medication, and sometimes surgery, as guided by your healthcare team.
How is genetic testing for MED done?
Genetic testing for MED typically involves providing a blood or saliva sample. DNA is extracted from this sample and analysed to look for pathogenic variants in genes known to cause MED, such as COL9A2, COMP, or MATN3. This process is usually arranged through a clinical genetics service.
References
- Anthony S, Munk R, Skakun W. Multiple epiphyseal dysplasia. The Journal of the American Academy of Orthopaedic Surgeons. 2015. PMID: 25667404
- Adam MP, Bick S, Mirzaa GM. Multiple Epiphyseal Dysplasia, Autosomal Dominant. 1993. PMID: 20301302
- Dawson PA, Elliott A, Bowling FG. Sulphate in pregnancy. Nutrients. 2015. PMID: 25746011
- Adam MP, Bick S, Mirzaa GM. SLC26A2-Related Multiple Epiphyseal Dysplasia. 1993. PMID: 20301483
- Olsen BR. Collagen IX. The international journal of biochemistry & cell biology. 1997. PMID: 9363632
- Wordsworth P. Genes and arthritis. British medical bulletin. 1995. PMID: 7552062
- Unger S, Hecht JT. Pseudoachondroplasia and multiple epiphyseal dysplasia: New etiologic developments. American journal of medical genetics. 2001. PMID: 11891674
- Unger S, Bonafé L, Superti-Furga A. Multiple epiphyseal dysplasia: clinical and radiographic features, differential diagnosis and molecular basis. Best practice & research. Clinical rheumatology. 2008. PMID: 18328978