Researches on human subjects vs. those on mice

To identify the etiologic genes and their polymorphisms, correlation between genotype and phenotype is the essential step.  For this purpose, it is essential to have a whole set of single nucleotide polymorphisms (SNPs).  Because of the difference between different ethnic groups in the kind and frequency of SNPs, it is first essential to have a whole set of SNPs in Japanese to find the disease susceptibility genes of common diseaes in Japanese.  ]those responsible genes and their polymorphisms may or may not be the same with those in other ethnic groups.  

Thus, the struggle to find the disease susceptibility genes and their polymorphisms is a long-lasting effort for many researchers tackling with the genome diversity.  

In contrast to the enormous diversity in human subjects, experimental mice have been genetically purified.  Their genetic background is homogeneous in one strain, thus being called as a clone.  By crossing the two different cloned strains of mice, it is possible to analyze in detail the contribution of the genetic background on the phenotype.  

The genome sequence of mice has been completed.  In addition the information on SNPs of mice of different strains are now available.  The production of transgenic mice which has the overexpression of target gene or knockout mice which has the dissapearance of target genes is now routinely possible for mice.  

Based on these consideration, the function of genes in vivo can be studied by the case-control association study on human subjects, and crossing mice strains with the quantitative measurement of the phenotype.  We are thus conducting both human study in parallel with mice study.