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
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
- High blood pressure
- Certain types of cancer (such as breast or colon)
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.