PHARMACOGENOMICS: MEDICINES TAILORED JUST FOR YOU
When patients with that gene variant are treated with azathioprine, its blood levels built up to toxic levels, leading to acute bone marrow failure. This happened to a boy who was started on the drug and had to be rushed to the Mayo Clinic for a marrow transplant, which saved his life. A pharmacogenomic genetic test has been developed to identify patients with this deficiency, which permits the use of an alternative therapy. The benefit of this test cannot be overemphasized these patients.
b.- SNPs have been identified that: 1.- prevent their carriers from metabolizing the cholesterol-lowering drug pravastatin, 2.- prevent clozapine, a drug for schizophrenia from helping patients with this disorder, and 3.- inhibit the metabolism of procainamide, a medicine for heart arrhythmias, leading to sometimes-fatal liver disease.
c.- It has been found that drugs used to treat asthma known as beta-two agonists react with a lung protein that act as its receptor. The gene coding for this receptor has two variants that differ in one SNP. The protein coded for one of the variants does not recognize the drug rendering it useless. Thus, people with this mutation are not benefited by those drugs.
d.- Finally, it has been shown that the drug tacrine is of little use to Alzheimer´s patients who carry a gene polymorphism called ApoE4.
You can see then, that things are advancing rapidly in this new science. In the coming years we will see more important advances that will save lives and make life easier for all of us. To finish, I would like to emphasize that the second approach is very expensive because finding the genes, identifying the proteins they code for, and designing the drugs to treat the disease are lengthy and costly processes. Just to give you an idea, the development of a successful drug, that is, one that gets to the market cost around 500 million dollars. To make it worthwhile the drug companies will target those genes that cause common diseases. And even though the drugs will be more expensive, the treatment itself will cost less because it will be guaranteed that the drugs will always do their job without side effects.
If you want to see pharmacogenomics in action please visit the excellent educational site of
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