Spotlights on Pharmacogenetics of Schizophrenia and Depressed Mood

There is an important issue in pharmacogentics which is “polymorphism”: it is a variation in the DNA sequence that is present at an allele frequency of 1% or greater in a population. It is most commonly in the form of Single base pair substitutions named Single Nucleotide Polymorphisms (SNPs), the location or the number of repeats, deletions, or critical splice sites. The interfaces between genetics and drug metabolism have recently been the subjects of intense research activity. Pharmacogenomics uses molecular biological techniques to study genes in relation to drug therapy for specific diseases in order to identify new treatments. Pharmacogenetics investigates the genetic basis for differences in individual responses to drugs with regard to their metabolism and transport in the body. It involves the role of many drugs, acting on different body systems, in the development of genetic polymorphism especially that responsible for metabolising enzyme as cytochrome p450 isozymes that affect their abilities in either induction or inhibition of drug metabolism and elimination. Genes of these drugmetabolizing enzymes possess Single Nucleotide Polymorphisms (SNP) with an allelic site that may also have more than one SNP. Genotype is the detailed gene structure of an individual whereas the more commonly measured phenotype is the outcome of metabolism of a drug in an individual. Since phenotype is the result of interactions between genetic make-up and the environment it is not always concordant with genotype [1-4].