5 Ways Medicine Is Getting Personal Why Personal Genomics Matters to You Genomics is the study of the human genome, genetic mapping and DNA sequencing. Sounds like the stuff of science fiction, or maybe a really boring party conversation, but either way, genomics is something you should care about. It's a science that's rapidly revolutionizing medical care. Here are five ways genomics is changing the future of medicine and why it should be important to you. Medicine Gets Personal Tweet Chat Today at 1 p.m., ET Your Genome Is Unique The human genome is stunning for its sheer complexity. Each of us has 23 chromosomes for a total of about 3 billion DNA base pairs. You inherit a chromosome from each of your parents, so double that to 6 billion. Between 3 million and 5 million of your base pairs differ from those of the person sitting next to you, said Dr. Eric Green, the director of the National Human Genome Research Institute. These genetic variations represent only a small corner of the human genome but reveal a lot of information about your health, both now and in the future, he said. Technology has made genetic sequencing a relatively cheap and speedy process. The Human Genome Project, which was the first successful attempt to sequence the full human genome, cost more than a billion dollars and took more than a decade to complete. Now for less than $5,000, a full gene sequence can be decoded in five days or less, Green said. By the end of the year, he expects advances in technology will allow scientists to sequence an entire gene in less than 24 hours. Genomes Help Diagnose Disease Genomics is already used in clinical settings to help diagnose and treat diseases from cradle to grave. In children, it helps diagnose developmental delays, intellectual disabilities, autism spectrum disorder and birth defects, to name a few. Early and accurate diagnosis allows physicians to target medical care and provide families with important information about genetic risks for siblings. In adults, genomics help fight cancer. Angelina Jolie highlighted this fact when she tested positive for a BRCA gene mutation that is strongly associated with a risk of developing breast cancer. After factoring this information in with a strong family history of breast cancer, the actress chose to undergo a pre-emptive double mastectomy. For those who already have cancer, Green said that it was now possible to sequence the genome of a tumor, identify the genetic variants that are the likely cause of the disease and personalize treatment. The Right Treatment at the Right Time We all respond differently to medications. Sometimes they work well, sometimes they don't work at all and sometimes they make one sicker. Green said that how a person metabolizes a drug is determined by genetic factors. Physicians can use this information to design highly individual drug regimens. For example, abacavir, a drug commonly used to treat HIV, causes a severe reaction in about 5 percent of patients, which often leads to life-threatening complications. Doctors suspected that these patients had a hypersensitivity to the drug because of an overreaction by their immune systems. Clinical trials found this to be the case. Patients now commonly undergo gene sequencing to test for possible reactions to the drug, Green said. Mystery Diseases Get Solved The crotchety hero of the TV show "House" took an entire episode and untold resources to figure out which mystery disease plagued his patient of the week. Green said a simple genome sequence could now crack the case with far less fuss up to 50 percent of the time. Green hopes this puts an end to patients forced to wander from doctor to doctor and clinic to clinic in search of a cure for strange and uncommon ailments. He said that genetic testing would revolutionize the treatment of diseases too rare to attract funding for studies or subjects for clinical trials. Such conditions are all too often misdiagnosed or underdiagnosed and go too long without treatment, he said. Genetic testing can't yield an answer in every unsolved mystery, Green said. Doctors can't always tell which variation is causing the problem, or they're still interpreting the genetic data. Green hopes that will change as genetic testing becomes the norm for conditions that defy conventional diagnostics. Genomics Informs Lifestyle Choices Genomics yields some answers about health that are crystal clear, Green said. In Jolie's case, for example, there was a definite link between a BRCA gene mutation and an increased risk of breast cancer. The same was true of Lynch syndrome, an inherited condition, and a heightened risk of colon cancer. But for many other illnesses with a genetic component, there are shades of gray. With Alzheimer's, diabetes and obesity, for example, we don't yet have enough evidence to know how big a role genetics plays or how lifestyle and genetics interact, said Green. While there is some preliminary evidence to suggest there is a powerful genetic component to these diseases, science can't say for certain which genetic variations render a person susceptible, and to what degree. Green also pointed out that until more answers became available, it's difficult to tell people to change their ways because of what their gene profile reveals. And it's not certain people will be quick to change their health habits even as the evidence for a genetic basis for certain diseases grows stronger. Interested in knowing more about the genomics revolution in medicine and what it means for you, now and in the future? Join ABC Health for a tweet chat today about personalized medicine. The chat is led by Dr. Richard Besser, ABC News' chief health and medical correspondent, and will be attended by top genomics experts from all over the world who have gathered to attend the Individualizing Medicine 2013: From Promise to Practice conference at the Mayo Clinic in Rochester, Minn., this week. Do you have a burning question about how genomics is being used in health care? Post it in the comments section, and we'll try to address it. You can find out more about how to join the chat here. And be sure to check out the live blog during and after the chat for expert commentary, fast facts, photos, video and more. Mobile users, follow this link for the live blog.