DMD-associated Dystrophinopathies

What is UNITY Fetal Risk™ Screen for DMD-associated dystrophinopathies?

UNITY Fetal Risk Screen is a carrier screening and fetal risk assessment for your pregnancy all in one convenient blood test. The first step is identifying if you are a carrier for DMD-associated dystrophinopathies. If you are not a carrier for DMD-associated dystrophinopathies, your baby’s risk of having DMD-associated dystrophinopathies is reduced.

If you are a carrier and currently pregnant, UNITY Fetal Risk Screen will automatically determine the sex of your baby, since this condition can affect males more severely than females. The fetal sex, along with your DMD carrier screening results, will help determine your baby’s risk of having a DMD-associated dystrophinopathy is. 

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What are DMD-associated dystrophinopathies?

DMD-associated dystrophinopathies are a group of inherited conditions, including, Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and DMD-associated dilated cardiomyopathy. These are conditions that occur most often in males and affect the muscles, causing muscle wasting and muscle weakness that gets worse over time. The symptoms, severity, age of onset, and rate of progression can vary. Common symptoms include difficulty running, climbing, and getting up from the floor. Learning disabilities and problems with memory can also be present. Progressive enlargement of the heart (cardiomyopathy) can also occur and lead to heart failure.

In more severe cases, like Duchenne muscular dystrophy (DMD), individuals usually experience symptoms in early childhood and often lose the ability to walk, needing a wheelchair during their teenage years. Becker muscular dystrophy (BMD) is a milder form and progresses more slowly, allowing some to continue walking into adulthood. DMD-associated dilated cardiomyopathy, the mildest form of DMD-associated dystrophinopathies, primarily affects the heart muscle, leading to heart problems and congestive heart failure, without skeletal muscle weakness.

Life expectancy varies, with many individuals with DMD living into their 20s or 30s. Treatments, including physical therapy and medications, help manage symptoms and improve quality of life. Gene therapy may also be available for some individuals. Genetic testing can sometimes predict which condition is more likely, however, it cannot always provide definitive answers.

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How are DMD-associated dystrophinopathies inherited?

The gene associated with DMD-associated dystrophinopathy is called DMD. It is located on the X chromosome. Typically, females (XX) have two copies of the DMD gene and males (XY) have one copy. Males that inherit a non-working DMD gene are expected to be affected with a DMD-associated dystrophinopathy. Up to 24% of females inheriting a non-working DMD gene will have varying symptoms of DMD-associated dystrophinopathies, which may include heart problems, muscle weakness, and muscle cramping.

Usually, carriers of genetic conditions do not have any symptoms themselves. However, in the case of DMD-associated dystrophinopathies, female carriers have an increased risk of developing heart problems, like cardiomyopathy. Carriers may also experience symptoms like muscle weakness and cramping. For those who are identified as a carrier of a DMD-associated dystrophinopathy, a cardiology evaluation is recommended. 

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Who should consider screening for DMD-associated dystrophinopathies?

Carrier screening for DMD-associated dystrophinopathies is recommended for pregnant individuals or those considering pregnancy who have a family history of a DMD-associated dystrophinopathy.

With UNITY Fetal Risk Screen, one test can tell you if you are a carrier for a DMD-associated dystrophinopathy and help determine your baby’s risk by providing fetal sex, as this condition typically affects males more severely than females. Depending on your results, your provider may discuss additional confirmatory testing that can be done either before or after delivery.

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UNITY Fetal Risk Screen Workflow for DMD-associated dystrophinopathies

Test as early as 9 weeks‍

Your blood sample can be collected in the doctor’s office, at a local lab, or through our mobile services. Your blood sample is shipped to our CAP/CLIA certified laboratory in northern California.

UNITY Aneuploidy™  Screen + UNITY Fetal RhD™  and Fetal Antigen™  results as early as 10 weeks‍

Within about one week from lab receipt, your doctor will receive the baby’s risk score for aneuploidies (chromosome conditions) and fetal RhD and fetal antigens (if added). You will receive a text or email indicating your results are available on our portal, or your healthcare provider may call you with the results.

Carrier status + fetal risk assessment results as early as week 11‍

Within about two weeks from lab receipt, your doctor will receive the results of your maternal carrier status testing. If you were found to be a carrier for any X-linked condition tested, UNITY Fetal Risk Screen will automatically determine the sex of your baby to provide further clarity in their chances of being affected with that condition. You will receive a text or email indicating your results are available on our portal, or your healthcare provider may call you with the results.

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What do DMD-associated dystrophinopathies carrier screening results mean?

Your UNITY Fetal Risk Screen results will tell you if you are a carrier for  DMD-associated dystrophinopathies or other conditions. Then, if you are currently pregnant and a carrier for DMD-associated dystrophinopathy, UNITY Fetal Risk Screen will provide the sex of your baby to help determine your baby’s risk of having a DMD-associated dystrophinopathy. The fetal risk will be reported out as a “High Risk” or “Increased Risk.” Your report will have specific information about your results, further testing available, and recommendations for you as a carrier.  

Although UNITY Fetal Risk Screen is a highly accurate screening test, diagnostic testing is strongly recommended to determine whether your baby is affected with DMD-associated dystrophinopathy. Confirmatory genetic testing during pregnancy or after birth can determine whether or not your baby is actually affected. 

• Before Birth:
  Testing for DMD-associated dystrophinopathy during pregnancy can be performed by obtaining a sample of placenta (chorionic villus sampling or CVS) or fluid around your baby (amniocentesis) which both contain DNA that is representative of your baby. A CVS is ideally performed between 10 to 13 weeks pregnancy while an amniocentesis is performed between 15 to 24 weeks pregnancy. Both procedures are safe, but have a small risk for pregnancy complications, including miscarriage.
• After Birth:
  ‍Testing for your baby can be performed after birth through a blood test as a newborn or with your baby’s pediatrician. 

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Frequently Asked Questions

‍Is there a cure for DMD-associated dystrophinopathies?

‍Currently, there is no cure for Duchenne muscular dystrophy (DMD) or other DMD-associated dystrophinopathies. However, various treatments can help manage symptoms, slow disease progression, and improve quality of life. These may include corticosteroids, physical therapy, assistive devices, and cardiac and respiratory support. Additionally, emerging therapies such as gene therapy and exon-skipping drugs are being researched and may offer new treatment options in the future. 

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What is the difference between the various DMD-associated dystrophinopathies?  

DMD-associated dystrophinopathies are a group of inherited conditions, including, Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and DMD-associated dilated cardiomyopathy. 

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Duchenne muscular dystrophy (DMD) is typically the most severe form of these conditions with progressive muscle wasting and weakness that begins in early childhood. Those affected with DMD often lose the ability to walk, needing a wheelchair during their teenage years. Progressive enlargement of the heart (cardiomyopathy) can also occur and lead to heart failure.

Becker muscular dystrophy (BMD) is typically a milder form of the DMD-associated dystrophinopathies. The symptoms progress more slowly, allowing some affected individuals to continue walking into adulthood.

DMD-associated dilated cardiomyopathy is the mildest form of DMD-associated dystrophinopathies. This condition primarily affects the heart muscle, leading to heart problems and congestive heart failure, without skeletal muscle weakness. 

Females who are carriers of DMD-associated dystrophinopathy have an increased risk of developing heart problems, including cardiomyopathy, in adulthood. Carrier females may also experience symptoms like muscle weakness and cramping. Due to these risks, a cardiology evaluation is recommended to monitor and manage any potential heart-related issues.

Genetic testing can sometimes predict which condition is more likely, however, it cannot always provide definitive answers.  

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How can DMD-associated dystrophinopathies affect pregnancy and childbirth?‍

DMD-associated dystrophinopathies can affect pregnancy and childbirth in several ways, particularly for individuals who are manifesting carriers or have a milder form of the condition. Potential concerns include muscle weakness, respiratory or cardiac complications, and an increased risk of pregnancy-related complications such as preterm labor or difficulty with pushing during delivery.

It is important for carriers of DMD-associated dystrophinopathies to consult with a healthcare team, including a maternal-fetal medicine specialist and a cardiologist, before and during pregnancy. 

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Treatment & Resources  

• CureDuchenne
• Muscular Dystrophy Association
• Parent Project Muscular Dystrophy
• Medline Plus