Genomics—A New Era For Medicine - The Future of Medicine

DNA Double Helix

We have entered into a new era in medical care, the era of genomic medicine. In coming years, we will see an improved ability to diagnose a disease and even to predict diseases to come later in life. A much more accurate prognostication of what will happen as the disease progresses and how it responds to medications will be offered, and treatment will improve. Drug therapy will change so that new drugs will be more effective and much safer. Physicians will be able to select a drug based upon an individual patient’s personal way of responding to that drug, both in terms of greater effectiveness and in terms of reduced side effects.

Even the foods we eat will be understood in terms of how they affect a specific individual. Vaccines will be “designed” for an individual patient who has, for example, a particular type of cancer that has been reduced but not totally eliminated. Finally, actual gene therapy—the introduction of a new gene to correct one that is diseased or will cause disease—will become commonplace, such as a true cure for sickle cell anemia or perhaps cystic fibrosis. Genomics will permeate across all branches of medicine.

Medical practice changed dramatically in the middle of the last century. Earlier, the physician attempted to understand what disease was present so that he could tell the patient and family its likely outcome. Specific therapies were few and far between. Then medicine became a true science with an increasing understanding of the cellular and molecular mechanisms that underlie each illness. With that developing knowledge, doctors could begin to treat disease with greatly improved medicines, such as penicillin for infections, tPA for breaking up blood clots in a stroke or heart attack, and drugs like phenothiazides for serious mental illnesses like schizophrenia.

Human Chormosomes

Doctors and patients both saw penicillin as a miracle drug when it first was used to treat serious pneumonias. I am still in wondrous amazement when I see a person with a stroke come to the emergency room unable to move his left side, only to watch him stand up and walk an hour later after receiving tPA. And the state mental hospitals—long used to “warehouse” individuals with chronic mental illnesses—have been eclipsed by the use of potent drug therapies that get people back home and enjoying life again.

But now we are entering a whole new era. The genomic era will allow for a change in your physician’s basic approach, from one focused on detecting a disease and treating it, to one where she is focused on predicting a disease later in life and prescribing a preventive approach.

The Emergence of Genomics

Concept
  • Sequence of 30,000 human genes
  • Determine the function of each gene over time
  • Allow:

    —Prediction
    —Prevention
    —Specific Therapy
    —Create drugs to block/induce an action
Goals
  • Replace defective genes
  • Understand cellular receptors
  • Develop designer Vaccines

Consider Anna Blumenthal, a thirty-four-year-old single woman employed as a financial consultant with a major accounting firm in the mid-Atlantic area. She began to have intermittent episodes of breathing difficulty and her doctor diagnosed asthma, a condition in which the smooth muscles around the airways deep inside the lungs begin to constrict, making it difficult to move air in and out and creating the characteristic wheeze during exhalation. Her doctor reviewed a variety of things she could do at home to reduce her chance of developing asthma attacks and gave her some preventive medications as well. He also gave her a prescription for an albuterol inhaler and told her to keep it handy for use in case of an asthma attack.

She followed her doctor’s instructions, making some changes in her environment and taking the preventive medications regularly. However, at about two o’clock one morning, she woke up, struggling to breathe. Alone at night, it was scary. But she remembered the albuterol that was in her medicine closet. She had read the instructions before but now read them again.

Albuterol comes in a spray canister; you put your lips around a mouthpiece, press down on the canister, and out comes a measured amount of very fine spray. The idea is to press the canister while taking a deep breath in, so that the medicine will get deep into the lungs. Albuterol works because it interacts with a receptor on the lining of the airways of the lung, a receptor that can relax the smooth muscles that are causing the constriction. When albuterol finds that receptor, it breaks the action of the smooth muscle constriction. It doesn’t cure the underlying cause that created the constriction in the first place, but it can turn the attack around in the short term. This receptor is the product of a specific gene that is part of our DNA. So we can say that our DNA directs the production of this receptor along our airways that will respond to albuterol.

Anna knew that after breathing in the albuterol she should begin to feel relief within a few minutes. She put the mouthpiece in, depressed the canister, breathed in the spray, and repeated it about a minute later, as directed. Then she waited, but nothing happened. Indeed, it was getting more difficult to breathe not less difficult. Now she really was scared because the promised relief had not arrived. Why? Because Anna is one of those rare people who are born with a gene that directs the production of a slightly different receptor on the lining of her airways, and this slightly different receptor does not respond to albuterol.

The middle of the night during an acute asthma attack is hardly the time to discover that you are among the unfortunate few. But for years physicians have been unable to predict which patients would not respond to albuterol. As a result of genomics, soon it will be possible to know who will not respond, so that an alternative medication can be prescribed and a long night of distress—and fright—can be avoided.

Pharmacogenomics

Using Genomic Information
  • Drug companies can create drugs with:
    Specificity
    Safety
  • Physicians can select prescription based upon:
    Individual genomic testing


    —Drug that is active in that person
    —Drug that is safe in that person

 

 

Last Modified: June 11, 2010


Copyright (c) Stephen C. Schimpff, MD