As the price of genetic sequencing of an individual's DNA drops, personalized medical genomics will become increasingly integral to prescribing drugs and treating illnesses, leading genome researcher Craig Venter wrote in a commentary for the journal Clinical Pharmacology & Therapeutics. He predicts that genome-based healthcare will help to prevent adverse drug reactions by pinpointing those who respond differently to drugs due to differences in drug metabolism genes. Understanding an individual's genetic makeup will also help tailor drug treatments to individual patients.
Currently drugs are tested on different ethnic groups to identify those populations most prone to adverse reactions or ineffective drug metabolism. But as personalized genetic medicine becomes more affordable, the practice of predicting an individual's response to a drug based on their race will become obsolete, says Venter. Differences between ethnic populations can often be attributed to a higher incidence of genetic mutations in drug metabolism genes among certain populations. However, there is also a high degree of genetic diversity within an ethnic population, leading Venter to argue that race is 'insufficient' to predict whether a person carries a variant of a gene.
To illustrate this point, Venter and his colleagues, at the Craig Venter Institute in Rockville Maryland, compared the DNA of the only two individuals who have to date had their entire genome sequenced: himself and James Watson, who discovered the structure of DNA with Francis Crick in 1953. Venter, in a parallel effort with the publicly funded Human Genome Project, was the first to sequence an entire human genome - his own - in 2000.
The two men are both 'self-identified Caucasians', yet when Venter and his colleagues examined six genes known to be involved in drug metabolism, three of the six genes varied between Watson and Venter. Watson's genome showed a mutation in the drug metabolism gene CYP2D6, which is rare in Caucasian but common in East Asian populations. This mutation would make some painkillers ineffective, as well as some drugs prescribed for cancer, heart arrhythmia, and depression. 'It is unlikely that a doctor would guess that optimal drug dosages might differ for Drs Watson and Venter without knowledge of their genetic data or extensive medical histories,' the Venter wrote in his commentary.
In an interview with New Scientist magazine, Venter said 'race-based medicine doesn't have any real basis in science. You can look at somebody's skin colour, but it doesn't necessarily tell you much about the rest of their genome, or how they'll respond to drugs, or which drugs they'll respond to.' He argues that drug treatments tailored to an individual's genome, by using an individual's genetic information rather than their ethnic background, will help prevent the thousands of cases of adverse drug reactions occurring each year.