What is Genetics? : Frequent Questions & Answers

Can a person’s ethnic background affect how likely they are to get a disease?

The vast majority of our DNA code is identical to each other. In fact, only about 0.1% of our DNA differs from person to person! It is this 0.1% that makes each of us different and unique. These differences are what make us look different (i.e. height, hair color, and eye color), and also are what may put people at risk for certain disease. Because of this, some genetic conditions are found more often in people of a specific group. Most of these conditions are recessive conditions. This means that both parents, mom and dad, must be carriers of a mutation in the same gene for them to have a child with the condition. Carriers typically don’t have symptoms of the disease. In fact, most people don’t know they are carriers for one of these conditions until they have a child with the condition or they have carrier testing.

For example, people of Northern European background (Caucasians) have a higher chance than people of other ethnicities of having a child with a disease called cystic fibrosis (CF), a severe disease that affects the lungs, pancreas and digestive system. This is because about 1 out of 29 people of Northern European descent is a carrier for CF. Another example is sickle cell anemia, which is a blood disease most common in people of African descent. About 1 out of 10 African-Americans are carriers of sickle cell anemia and often are said to have sickle cell trait. There are many other conditions that are more common in specific ethnic groups including Tay Sachs disease in the Ashkenazi Jewish population and thalassemias in people of Mediterranean descent. Genetic counseling and carrier testing are routinely offered for families who are planning a pregnancy or for women who are pregnant to see if their child is at risk for these types of genetic conditions. If you would like to find a genetic counselor in your area, please go to the National Society of Genetic Counselors, or NSGC website.