Familial Dilated Cardiomyopathy
Dilated cardiomyopathy (DCM) is a heart disorder characterized by a heart that is enlarged in diameter and weak in pumping function. Although there are many causes that can lead to a dilated heart, in some subset of patients the DCM appears to be inherited. We suspect that this familial form of DCM affects approximately 1 in 2500 people in the United States, although it may be more common.
People with DCM may experience palpitations, have difficulty breathing when walking or exercising, and can have difficulty with excess fluid in their body, particularly in the legs. DCM can progress to severe heart failure and can sometimes trigger life-threatening arrhythmias resulting in sudden death.
DCM is diagnosed by echocardiogram. Because multiple conditions can cause DCM (such as blockages in the coronary arteries, a past heart attack, or a viral infection) a cardiologist typically screens for these conditions to make sure they are not responsible. At the same time, a family history of DCM should be obtained, as it can be very helpful in pointing to a genetic basis.
Treatment for DCM is similar to that of heart failure, and involves taking a set of common medications (e.g. beta-blockers, ACE-inhibitors, diuretics). Because DCM patients may be at higher risk of sudden death from an unstable heart rhythm, they are sometimes given an implantable defibrillator.
Over 20 different genes have been associated with DCM but these genes are responsible for only about one fifth of cases. We expect to identify more genes responsible for DCM as our knowledge in cardiac genetics improves over time.
DCM can be inherited in an autosomal or recessive dominant manner. In the autosomal dominant case, this means that each child of a parent with DCM has a 50% chance of inheriting the genetic mutation associated with the condition. The genetic mutation does not skip generations. However the condition may appear to skip generations because some people carry the genetic mutation for DCM but have a normal EKG and no symptoms. Even if a person with the genetic mutation does not have symptoms or an abnormal EKG, they can still pass on the gene mutation to their children and their children could develop symptoms. The chance of inheriting the gene mutation is the same for men and women. Many people who inherit the genetic mutation will never have any health problems related to DCM syndrome. In the recessive case, a person needs to inherit a mutation from each of their parents to develop the disease.
Genetic testing can be done to try to identify the genetic mutation causing DCM so other family members can have genetic testing to determine their risk for abnormal heart rhythms associated with the condition. The results of genetic testing can sometimes be useful in medical management for individuals with DCM, although genetic test results typically do not affect medical treatment.
Since familial DCM is a genetic condition, the family members of someone who has the condition may be at risk of developing the abnormal heart rhythms, fainting or sudden death. Close relatives (parents, siblings, and children) of someone with DCM should be evaluated for the condition by consulting a cardiologist familiar with DCM or through genetic testing if the gene mutation associated with the condition in the family has been found.
There are no specific behaviors for people with DCM to avoid, though liquid and salt intake are sometimes watched carefully if there are problems with fluid buildup. Individual recommendations should be made with the help of a cardiologist.