About Genetic Testing
Gene Polymorphism Analysis and Pharmacogenomics
What is a SNP
Although 99.9% of human genes have the same sequence, as a result of various studies, it has been discovered that there are differences in the genome sequence amongst individuals. The differences are called genetic polymorphisms and there are several types. One drawing particular attention is the type in which only a single nucleotide in the genome sequence differs between an individual and members of a specific population. These are called SNPs (Single Nucleotide Polymorphisms).
The Difference Between a SNP and a Mutation:
Usually when a single nucleotide in the genome sequence differs from others, it is called mutation. However there is a slight difference between a SNP and a mutation; the frequency in which they occur. Technically, a polymorphism is a DNA variation in which each possible sequence is present in at least one percent of a population, if it is present in less than one percent of the population, it is considered a mutation. So for example, if one percent or more of the population in Japan had certain DNA variation, it would considered a polymorphism. And if a limited number of population had a certain DNA variation (less than one percent) if would considered a mutation. Still SNPs originate from one’s ancestor’s mutated genes. Mutations which occurred a long time ago and have been passed down through generations until a certain percentage of the population have them, are now considered to be polymorphisms.
Significance of SNP Analysis:
SNP analysis is a method of research to scientifically discover which genes relate to individual differences in constitution, susceptibility, or predisposition to disease by analyzing an individual’s SNPs. Specifically, correlation of clinical data and SNP data of patients with certain a disease and ones who don’t have any health issues are statistically analyzed. This research method is particularly effective in understanding the causes of lifestyle-related diseases. Moreover, after considering lifestyle and other factors, research for genetic predisposition to a disease can be focused on. If genes related to a disease and candidate drugs effective towards those genes are discovered, since a correlation of the genes and the disease are known, it would be easier to choose a drug with high efficacy and fewer side effect. It is possible to have even greater results with SNP analysis if we devise ways to combine groups for comparison. For example, if there could be a study comparing gene polymorphisms of responders and non-responders being treated with a certain drug, the result could greatly contribute to predicting efficacy of the drug before its actual use. This type of research related to drug use is called “pharmacogenomics”. Using genome information to improve treatment is a promising part of modern medical science. In the near future, based on scientific evidence, each patient could be provided with most suitable treatment, the proper drug and dosage, which would hopefully develop into “tailor-made medicine“.