September 20, 2000 – In what appears to be the demonstration that genetic information opens a new era in the practice of medicine, a team from the American company Genaissance Pharmaceuticals Inc., of New Haven, Connecticut, claims to have discovered the differences personal genetics that predict the response of asthma patients to a certain drug.
The researchers analyzed the DNA of 121 people with asthma and found four different DNA sequences on a gene involved in relaxing muscles in the lungs. Albuterol, a drug designed to stimulate this gene and decrease wheezing in asthma, worked very well in patients with a particular sequence, not at all for people with a second sequence, and moderately in the other two.
Applying this finding to all diseases and drugs could identify differences in why one patient responds well to one drug and another not at all. At present, clinical tests supporting the use of a drug are based only on statistical data showing average results for all people studied and do not take individual differences into account at all.
Pharmacogenomics, that is, the study of drugs in relation to genetic differences, is based on the fact that the chromosomes that make up the genetic code of every human being vary by about 1 in 1000 “letters”. human genome (the entire genetic code) is estimated to be around 2.3 billion “letters”. These small differences in everyone’s genetic code are called single nucleotide polymorphisms (PSNs) or single nucleotide polymorphisms. Some of these NHPs are like typographical errors and cause anomalies in the DNA while other NHPs do not seem to have consequences.
The team from the company Genaissance had previously discovered that Albuterol acted on a gene identified as the B2 adrenergic receptor and that this gene had 13 sequences in which the NHPs were located. By analyzing these NHPs, the researchers identified four common differences, or haplotypes. It is these haplotypes, a kind of genetic marker, that can predict a person’s specific reaction to asthma medication. All that remains is to create a test to quickly identify the haplotypes so that the doctor can know whether or not it is useful to prescribe Albuterol.
The Genaissance company plans to apply its technology to create tests that predict the response of patients to drugs for heart disease, schizophrenia, high cholesterol and more.
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According to The Boston Globe and Associated Press
Connie M. Drysdale, Dennis W. McGraw, Catharine B. Stack, J. Claiborne Stephens, Richard S. Judson, Krishnan Nandabalan, Kevin Arnold, Gualberto Ruano, and Stephen B. Liggett Complex promoter and coding region 2-adrenergic receptor haplotypes alter receptor expression and predict in vivo responsiveness Proc Nat Aca Sc 97: 10483-10488.