The first step in trying to determine if heart disease runs in your family is to draw a pedigree. A pedigree is a family tree that shows who has and who doesn’t have the condition of interest. It is drawn to organize information about the medical history of family members, illustrate who is affected, identify the pattern of inheritance, and identify who is at risk for disease. In drawing the pedigree, it is important to know whether your relatives have been diagnosed with any heart problems, died suddenly or unexpectedly, or have other major medical problems. Sometimes people may not be aware that they have a heart condition because their findings are so mild, they haven’t seen a doctor recently, or they haven’t had the appropriate tests performed. Knowing as many details as possible is important because sudden death can be mistakenly labeled as heart attacks, drowning, or car accidents. The sudden death of a previously healthy young person should be closely examined.

Because immediate, or first-degree, family members of a person with an autosomal dominant condition each have a 50% risk of inheriting the gene mutation that causes the family’s condition, they should be evaluated by an experienced cardiologist to see if they are affected. If a person is diagnosed with the condition, the first-degree relatives of that person should then be evaluated—a process called cascade screening.

How does inheritance work?

Genes are the basic units of inheritance and are made up of chemicals called DNA. Genes provide instructions for cells to make proteins that carry out all body functions and form our physical characteristics. We each have more than 20,000 genes, and each gene is present in two copies. One copy is inherited from your mother and one copy is inherited from your father. Genetic conditions are caused by a change (or mutation) in one or more genes passed from generation to generation.

Are genetic heart conditions passed down by dominant or recessive genes?

Most genetic heart conditions are inherited in an autosomal dominant pattern. Autosomal means that both men and women are equally affected. Dominant means that although there are two copies of each gene, a mutation in just one copy is enough to cause disease. Therefore, a person with an autosomal dominant condition has one normal copy of the gene and one copy with a mutation. The chance of passing the abnormal copy of the gene to a child is 1 out of 2, or 50%. By the same token, each child has a 50% chance of inheriting the normal copy of the gene and has no risk of developing the condition. On average, half of the members of a family with an autosomal dominant heart condition will develop the disease.



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Dr. Drew Sutton