Health Report Questions

What exactly is DNA, in a non-technical definition?

DNA, or deoxyribonucleic acid, is a very large chemical molecule that forms most of your genes and carries your hereditary information. DNA is formed from a series of building blocks, called nucleotides, into a long, coded chain that gives the instructions for development, from conception to adulthood. It also has instructions for the specialized functions of your body. For example, in your muscles, your DNA instructs the cells to form fibers and equips them to contract. In your eyes, your DNA tells cells to form photoreceptors to detect light. Each part of your body is formed and operates based on the instructions that are in your DNA.

What is the difference between genetics and genomics?

Genetics is the science of heredity, especially how characteristics are passed down through the generations by means of genes, and how inherited characteristics vary between individuals. Genomics is the study of the entire DNA sequence of an organism (the genome) and how the genome functions, including the regulation of gene expression in health and disease. The study of genetics and genomics will provide deeper understanding of living organisms and will allow the discovery of better diagnostics and treatments for certain disease conditions.

What are the markers and risk alleles you talk about?

Your DNA varies from other people's DNA, and that's what makes each of us unique. Variant positions in your DNA are known as genetic markers, and the variants are referred to as alleles. Each of us inherits two copies of genetic material, one set from each parent (except for the sex chromosomes---that's a different story). Most of your markers have two copies, which either are the same or are different variants. For example, let's say that the ability to freckle is encoded by a freckling marker, and that there are two alleles possible: A allele (freckles) or the B allele (no freckles). Your genotype for the freckling marker might be AA, AB or BB. So in this example, if your freckling marker reads BB, you probably do not have freckles. When we talk about disease markers, these are often described as having a risk allele (which gives you a higher predisposition for developing a disease compared to the general population), and/or a protective allele (which gives you a lower predisposition for developing a disease compared to the general population).

What does it mean to be a carrier? How will it affect me? How will it affect my children?

Some diseases are recessive. That means you must receive a copy of the disease-causing allele from each of your parents in order for you to exhibit the characteristics of that disease. If you are a carrier that means that your DNA contains only one copy of a disease-causing variant. Carriers do not typically have the disease themselves, but can pass the disease-causing variant on to their children. If both parents are carriers, then each child of the couple has a 25% chance of inheriting two copies of the disease-causing variant and developing the disease.

Why is genetic information important in my life?

Knowing your genetic information can lead you and your physician to make choices about your behavior and environment that could result in a better and healthier life for you. Genetics affects many things about your life: your susceptibility to disease, carrier status, sensitivity to drugs and much more. You can learn a lot about this information from genetic testing. For example, knowing that you have an increased genetic risk for obesity could lead you and your physician to make the choices about diet and exercise that could mitigate the on-set of obesity. Genetic factors that increase risk for common diseases such as Alzheimer's disease, cancer, diabetes and heart disease are found in more than 40% of the population. An analysis of your genetic makeup can reveal to your physician your risk for developing these and other diseases and potentially how you would respond to treatment.

Are my genes my destiny, or do things like diet and exercise really make a difference?

Your genetic profile may show increased risk for a particular health condition. However, being at risk does not mean you will contract it. Lifestyle factors such as a healthy diet and regular exercise are well documented to lower risk for many conditions such as high blood pressure. On the other hand, lifestyle factors such as tobacco smoking have been shown to increase one's risk of developing cancer and heart disease. In addition, early detection has been shown to increase the likelihood of successful treatment for many health conditions. If your genetic profile shows an increased predisposition for developing a condition, we recommend you discuss preventive and early detection options with your physician.

What are the next big breakthroughs in genetics likely to be?

New discoveries occur rapidly in the area of human genetics. The next breakthroughs will be in our understanding of how genetic and environmental mechanisms individually influence and combine to produce disease and much more. This knowledge has the potential to enable early prediction of health risk susceptibility, facilitate the prevention of some conditions through the discovery of new, targeted medications, and identify lifestyle changes that can help prevent or mitigate certain health conditions.