Why is genomic information helpful?

Each gene provides the blueprint for the production of a certain protein in the body. A particular protein may have an important role in drug treatment for one of several reasons, including the following:

• The protein plays a role in breaking down the drug.
• It helps with the absorption or transport of the drug.
• The protein is the target of the drug.
• It has some role in a series of molecular events triggered by the drug.

When researchers compare the genomes of people taking the same drug, they may discover that a set of people who share a certain genetic variation also share a common treatment response, such as:

• A greater risk of side effects
• The need for a higher dose to achieve a therapeutic effect
• No benefit from the treatment
• A greater or more likely benefit from the treatment
• The optimal duration of treatment

This kind of treatment information is currently used to improve the selection and dosage of drugs to treat a wide range of conditions, including cardiovascular disease, lung disease, HIV infection, cancer, arthritis, high cholesterol and depression.

In cancer treatments, there are two genomes that may influence prescribing decisions — the genome of the person with cancer (the germline genome) and the genome of the cancerous (malignant) tumor (the somatic genome).

There are many causes of cancer, but most cancers are associated with damaged DNA that allows cells to grow unchecked. The "incorrect" genetic material of the unchecked growth — the malignant tumor — is really a separate genome that may provide clues for treatment.