Did you know there are about 20,500 human genes? In recent years, we’ve learned so much about how genes work and why some diseases run in families. While we can’t change our genes, knowing we have a higher-than-average chance of developing certain diseases can help us take steps to lower our risks.

Genetics 101

We each inherit two copies of our genes, one from each parent. They are our personal instruction manual. Proteins do the work of building and maintaining our body. When genes that instruct the making of proteins develop mutations, it can cause disease. Although a mutation in a single gene can cause a disease (for example, sickle cell anemia), most diseases are the result of a combination of mutations along with lifestyle choices (such as smoking) and our environment.

Genes and Disease

Certain known mutations raise our risk for specific diseases. Inherited mutations in the BRCA1 and BRCA2 genes, for example, raise a woman’s risk of developing breast and ovarian cancer. Having these mutations does not mean that a woman will definitely develop one of these cancers. It just means she’s at a higher risk of doing so.

How much more? According to the National Cancer Institute, about 12 percent of women who don’t have these mutations will develop breast cancer at some point in their lives. In contrast, about 75 percent of women with the BRCA1 mutation and 69 percent of those with BRCA2 mutations will develop breast cancer by age 80.

Here are a few more examples. If you have a family history of high blood pressure, you are at risk for developing high blood pressure at a young age. If a man has a father or brother with prostate cancer, it more than doubles the risk he will also have prostate cancer. And, the most reliable indicator of a person’s risk for alcohol or drug abuse is actually his or her family history.

Family Health History

Several common illnesses, including heart disease, high blood pressure, asthma, diabetes and some types of cancer run in families. Knowing your family’s health history can help you determine if you have an increased risk, since inherited diseases tend to show up in distinct patterns. For example, if one or more close relatives have a disease, or they developed it at an earlier-than-average age, you may be at increased risk.

Should You Undergo Genetic Testing?

Ask your doctor if genetic testing makes sense for you. While it can be helpful for those at high risk, you’ll want to work with a qualified genetic counselor or go to a clinical human genomic program at a hospital where trained professionals can help you make sense of the results.

Facts About Genes

• We each have about 20,500 genes
• 99% of our genes are the same
• The remaining 1% account for our differences (such as hair color, height and predisposition to disease)
• Genes are why some diseases run in families

Common Inherited Conditions

• Heart disease
• Diabetes
• High blood pressure
• Asthma
• Certain types of cancer (such as breast or colon)

ACTION ITEMS

Share your family health history with your healthcare provider. In addition to making life­style changes (such as quitting smoking or losing weight), he or she may recommend additional ways to lower your risk, including medical treatments, such as screenings, preventive medicines, or even surgery to catch disease early so you can begin treatment right away.

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