The prevalence of FDC is, most likely underestimated as many affected individuals may not exhibit any symptoms. However, it is estimated that approximately 375,000 individuals in the United States have FDC. FDC affects males and females equally.

Familial isolated dilated cardiomyopathy is inherited as an isolated condition as opposed to other types of cardiomyopathy that could be a part of a more general syndrome. Thirty mutations have been found to cause FDC. A mutation in each of those genes can cause FDC. All these genes are responsible for encoding different components of the heart muscle. Most of the responsible genes code for proteins that are involved in contraction of the heart. Others encode for structural components of the heart, and some encode for proteins that ensure the heart functions properly.

One of the most common mutations that lead to FDC is a mutation in the gene TTN that encodes a protein called titin. Titin plays a key role in flexibility, stability and chemical signaling of heart muscle cells. Titin proteins produced by the mutated gene are abnormally short which lead researchers to believe that it disrupts chemical signaling of the heart.

When the heart is unable to pump blood efficiently due to genetic reasons, its muscles stretch to take in more blood. However, as the heart enlarges, it becomes thinner and weaker. Consequently, it becomes less and less efficient in pumping blood which leads to symptoms of the disorder.  

Most cases of FDC are autosomal dominant, meaning that one copy of the mutated genes puts the individual at risk of developing the disorder. However, in rare cases, autosomal recessive and X- linked inheritance have been observed.

FDC can remain asymptomatic for a long time and the symptoms are usually exhibited during the third and fourth decades of life. FDC leads to reduced ability of the heart to pump blood to the rest of the body. Consequentially, fluids may accumulate in the heart and lungs. Common symptoms are shortness of breath after physical activities or during sleep, cough, tiredness, swelling of the abdomen (belly) and/or lower leg, nausea, chest pressure and pain, and Irregular or rapid pulse. Paleness of the skin, wheezing, and excessive sweating are among other symptoms of FDC. Affected individuals may find it uncomfortable to sleep in flat beds. They may also experience changes in appetite, or more severe symptoms after eating. Symptoms of FDC usually develop over time. In some cases, the condition may never exhibit any symptoms.

FDC is characterized by enlargement of one or more chambers of the heart and a reduction of the contracting force of the heart muscle (systolic dysfunction). Diagnosis of FDC may be established through a detailed clinical evaluation, observation of symptoms and physical characteristics, a complete family and patient history, and performance of a variety of tests.

It is also very important for close family members of a patient with FDC to undergo genetic screening even if they do not exhibit the symptoms, because as mentioned before, symptoms may not develop until later in life, but early diagnosis of FDC and applying the right lifestyle can significantly increase the quality of life of affected individuals.

There are various specialized tests that help the physicians study and analyze the function of the heart. An electrocardiography (EKG) shows the electrical activities of the heart and helps reveal symptoms such as irregular heartbeat. In addition to EKG, an echocardiogram can study the motion and the function of the heart by analyzing the echo of sound waves that are sent towards the heart.  If the onset of symptoms is during infancy or early childhood, additional tests may be required to ensure that the symptoms are not the result of other potential disorders associated with dilated cardiomyopathy.

In another test, radionuclide ventriculography, radioactive material are injected into the blood in very small amounts. As a result, as the blood flows, the radioactive material leave a trace that can be studied using specialized cameras. This method allows physicians to study the shape of the heart.

Other tests that can be used to diagnose dilated cardiomyopathy include chest X-rays, MRI of the heart, heart biopsy, and CT scan of the heart. Once the diagnosis of dilated cardiomyopathy is established, genetic screening is required to determine if the condition is inherited or acquired.

Familial dilated cardiomyopathy is treated the same as dilated cardiomyopathy. The treatment for FDC varies from case to case and is dependent on symptoms and clinical findings. There are different drugs that can be helpful for affected individuals. Asymptomatic individuals can take drugs known as beta blockers and/or ACE inhibitors that prevent specific structures from binding to the heart muscle and decrease the workload of the heart muscle to prevent the progression of the condition. Diuretics are a type od medication that increases the urine production to prevent accumulation of fluids in body organs. Other medications include vasodilators that decrease blood pressure by relaxing blood vessels. As a result, the heart requires less energy to pump blood around the body. In addition, digitalis medications make the heart muscle more efficient and regulate the heartbeat.

There are devices such as defibrillators and pacemakers that can be implanted and use electrical simulation to help produce a regular heartbeat which can be useful for more severe cases. In most severe cases, the affected individual may require a heart transplant.

The prognosis of FDC varies significantly from case to case. Some individuals never exhibit the symptoms. However, FDC is usually a chronic condition and may worsen over time. It is very important to remember that early treatment can have a tremendous effect on improving the quality of life of the affected individual. That is why it is very important for people at risk to undergo genetic screening.

Lifestyle changes can improve the quality of life for affected individuals. Drinking alcohol and salt intake must be controlled. Excessive sodium in the blood increases the blood pressure, forcing the heart to pump more rigorously to pump blood around the body. Furthermore, body weight should be controlled and it is better to exercise at a moderate level to ensure that the heart is not under too much pressure.

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