Care Considerations for Carriers
Females carriers are usually not affected with Duchenne or Becker because they make enough of the dystrophin protein. However, they can have some symptoms of Duchenne, such as changes to heart function, mild muscle weakness, fatigue (a tired feeling), or cramping in their muscles. Rarely, a carrier has symptoms that are as severe as those of a male with muscular dystrophy. The term “manifesting carrier” is often used to describe a woman who has some of the symptoms seen in males who have Duchenne.
In addition, symptoms can be seen in young girls who are carriers of Duchenne. Although rare, it is important to be aware of this risk, and bring any concerns about muscle weakness, impaired balance or frequent falls, muscle fatigue, and cognitive or behavioral issues to your doctor. This is especially important if there is a known family history of Duchenne. Learn more about young female carriers of Duchenne.
All carriers should be evaluated by a healthcare provider familiar with Duchenne.
Most carrier females (about 80-90%) have no problems with their skeletal muscles. Some have mild muscle weakness, fatigue (a tired feeling), pain or cramping in their muscles. Rarely, a carrier has symptoms that are as severe as those of a male with muscular dystrophy. These issues should be addressed by specialists in these areas (ie, neuromuscular specialists (neurology or physical medicine and rehabilitation (PM&R), physical therapy, etc.) and followed regularly. They may suggest stretches, exercises, and/or medication for pain that may be helpful.
Carrier females have an increased chance of changes to heart function. It is not yet known how common heart changes are, but some studies have estimated that 10-50% of carriers have heart changes. The large majority of carriers will never need heart treatment or have health effects.
Because a small percentage of carriers may have serious heart concerns, however, it is important for all women who are carriers and women who are at risk to be carriers (for example, women with a son or brother with Duchenne) to have regular heart evaluations, beginning in their late teens/early adult years and, if normal, repeated every 3-5 years.
Women who know that they are carriers, or women who suspect that they might be carriers, should discuss heart screening with their doctors. The best screening plan is not yet known, so different healthcare providers might make different recommendations. Findings from a recent study suggest that beginning cardiac MRI in the third decade of life to evaluate for the presence of underlying cardiac disease should be considered. If there are any problems or potential problems found, the carrier may be referred to a cardiologist. If cardiac issues are found, they should be treated by a cardiologist who is familiar with heart failure and, if possible, knowledgeable about Duchenne.
It is important for carriers and potential carriers to have the best and most accurate information in order to make informed decisions about future pregnancies. Women have several reproductive choices to consider including pre-implantation genetic testing or prenatal genetic testing during pregnancy. These decisions are very complicated and personal and there is no “right answer.” Please speak with a genetic counselor if you are a carrier or if you have a child with Duchenne or Becker. A genetic counselor can review the benefits and risks for each of these procedures and discuss all of your options so you can make the best decision for you and your family. Learn more about reproductive options.
Learning that one is a carrier can cause strong emotions. It is not uncommon for women to feel sad, worried, or guilty after learning that they are carriers. Although no one is in charge of which genes they pass on to their children, many women wish that they could control their genes or take back the illness.
Carriers considering having children (or more children) may be afraid of the possibility of having an affected son (or another affected son). Sometimes the fears change their plans about having children. Some women choose to have prenatal genetic testing during pregnancy. Other women choose to have children no matter what. These decisions are very complicated and personal, and there is no “right” answer.
Manifesting carriers may have additional feelings related to the uncertainty around their own health. It is difficult to predict if the symptoms in a woman who is a manifesting carrier may get worse, and if so, at what rate. It can be especially challenging for manifesting carriers who are trying to take care of an affected son while dealing with their own symptoms.
Strong feelings related to being a carrier do not happen only in families with Duchenne or Becker; they may be found along with any genetic condition. Speaking to a healthcare provider, especially a genetic counselor or psychological counselor, or other mothers in similar situations about these feelings may be helpful.
Symptoms in Carriers
When thinking about symptoms in carriers, there are three different groups to consider:
Carriers with no symptoms
Most carriers fall into this category. About 80-90% of carriers have no muscle symptoms. Such carriers usually do not know that they are carriers unless a family member is diagnosed with Duchenne and they have genetic carrier testing.
Manifesting carriers have skeletal muscle, joint, or heart symptoms caused by the mutation in the dystrophin gene.
Germline mosaic carriers
Women with germline mosaicism most likely have no increased chance for skeletal muscle symptoms or heart changes related to Duchenne. Learn more about what it means to have germline mosaicism.
Learn More About Being a Carrier
In the past, there has not been a great deal of research focused on female carriers, but this is changing. The Duchenne Registry, started by PPMD in 2007, has always collected data on female carriers. In fact, we encourage all carriers to consider joining The Duchenne Registry.
If you have a child with Duchenne and they already have a registry account, you can add yourself to their account in the Family Member box and you both would share the same username and password. Carriers can also register themselves separately by creating a new account with a unique username and password. Either way, the data you share will help us advance research by providing a better understanding of the impact of being a carrier and the significance of different types of genetic changes.