Your genome holds the secrets to who you are and plays a big part determining your health – of course, so does eating right, exercising, getting enough sleep, whether your smoke or not, etc.
Just as you might inherit your father’s nose or your mother’s smile, diseases can be passed from one generation to the next. You might hear someone say “that illness runs in my family.” Doctors also want to know about the diseases that run in your family – known as your family health history. In some cases your doctor may order genetic tests to find out what you might have inherited from your parents.
When scientists finished mapping the first human genome in 2003, they discovered that health is not always related to a single gene. Some diseases are hidden within a person’s genome.
Your Genome & Your Health
Think for a minute about that pocketwatch (see Genetics vs. Genomics). What if a gear was missing – or an extra gear was thrown in – or all the right parts were there, but they were put together in the wrong order? The watch wouldn’t work well, if at all.
The same thing can happen in someone’s body. They might have changes in their genome – something missing or something extra or something out of order – that affects their health. That is called a variant (see box, at right).
Letters are the building blocks of the genome. So, sometimes when there is an important difference in the way the letters appear, it can signify a health issue.
The letters could be in the wrong order. Think of a spelling error.
Letters being out of order can certainly cause problems.
What if the letters should read CAT, but instead, they are out of order and read ACT:
Missing letters can affect your health, too.
Sometimes, letters are missing…AT instead of CAT, for instance.
Duplicated letters also can cause trouble.
And sometimes letters in the genome can repeat when there shouldn’t be extra copies:
In the same way that a spelling error changes the meaning of a word, a DNA variant changes the protein, and the protein may not work the way it should. When a protein doesn't do its job, it can result in a disease.
Such variants can be passed from one generation to the next. Or, they can happen spontaneously. Scientists are just beginning to understand what different types of variants mean and how they may interact with each other to increase your chances of getting an illness or to affect how severe your sickness might be if you do get the disease.