Currently, the clinical application of SNP geno-typing is limited for several reasons. Only approximately 5% of human DNA has a known function; thus, 95% of DNA remains to be deciphered. Knowing that pharmacogenomics attempts to explain the complexity of multiple genetic changes and its influence in drug response, we can ascertain that SNP descriptions of unknown regions are of minimal clinical utility. As molecular biology continues to unravel the transcript-structure-function relationship of the human genome, SNP genotyping may help to enhance the therapeutic decision-making process. Although pharmacogenomics is in its infancy, it equips health care providers with the power to use genetic information in an effort to improve patient care. It is not just a scientific application for the future; pharmacogenomics is a tool that can be used now to improve patient outcomes.

In late December 2004, for example, the U.S. Food and Drug Administration (FDA) approved the first pharmaco-genomic assay for identifying SNPs related to drug metabolism. The AmpliChip™ CYP450 (Roche Molecular Systems) is about the size of a credit card, with thousands of DNA molecules representing small variations in selected isoforms of the cytochrome P-450 (CYP450 2D6 and 2C19) enzyme system. Used in conjunction with current clinical evaluation tools, this chip provides genetic information about how a person metabolizes various medications, including anti-depressants, antipsychotics, beta blockers, some chemo-therapeutics, analgesics, and so on. The chip is based on 30 years of genetic research, but it represents an initial step into the realm of pharmacogenomic medicine. cheap cialis canadian pharmacy

It is worth noting that CYP450 2D6 and 2C19 have a strong genetic correlation and a minimal environmental correlation to polymorphic states, thereby representing the exception, as opposed to the norm, for polymorphisms. Future pharma-cogenomic assays must consider stronger environmental influences for clinical utility to materialize.