From the Genetics Laboratory to the Clinic
Personalized medicine involves analyzing a person's unique DNA to help determine who may be more likely to develop certain diseases so that preventive measures can be taken and, for those who develop a disease, to help create a customized treatment plan. To help understand the benefits of this new approach to medicine, refer to the following example patient profiles.
Example Case 1
In 2000, Jane Doe is diagnosed with depression, one of 20 million such individuals per year in the United States. She’s placed on a standard dose of a tricyclic antidepressant but still shows signs of confusion and difficulty concentrating. The physician interprets this as further signs of depression and increases the dose of the medication. In response, Jane develops agitation, nausea, and vomiting. She’s switched by her physician to an alternative tricyclic antidepressant.
In 2010, Jane can be genotyped for 30 pharmacogenetically relevant variants in 2 genes in the gene family cytochrome P450. Jane is found to be deficient in CYP2D6 and is placed on a selective serotonin reuptake inhibitor. This genotype also explains how she will respond to other drugs, such as codeine. The information is placed in her electronic medical record. As a result, other physicians of Jane’s who consult the medical record will be alerted to potential problems when attempting to prescribe drugs that may be contraindicated based on Jane’s predetermined genotype.
Example Case 2
In 2002, John Doe is diagnosed with hypertension and placed on his first beta blocker. He experiences shortness of breath and wheezing, with the hypertension remaining unresolved. He’s switched to another beta blocker by his physician. His hypertension is eased, but he experiences dizziness at the effective dose. John speaks to a friend and sees his friend’s physician as a new patient and receives a third beta blocker. The hypertension is controlled without significant side effects.
In 2009, the same patient is diagnosed with hypertension. The physician orders a cytochrome P450 genotype test. The test identifies him as a poor metabolizer for a class of drugs requiring the enzyme CYP2D6. The physician selects a beta blocker not metabolized by CYP2D6. The hypertension is controlled without significant side effects, in one visit, with one drug.
