Different Single Haplotype Block Is Defined In The Haplotype Block Structure Inferred And Htsnps Selection Effect

Common diseases such as cardiovascular disease, cancer, obesity, diabetes, psychiatric illnesses and inflammatory diseases, are caused by combinations of multiple genetic and environmental factors (King et al. 1992). Searches for causative variants in chromosome regions identified by linkage analysis have been highly successful for many rare single-gene disorders. However, linkage studies have been much less successful in locating genetic variants that affect common complex diseases, as each variant individually contributes only modestly to disease risk (Botstein and Risch, 2003; Risch 2000). A complementary approach to identifying these specific genetic risk factors is to search for an association between a specific variant and a disease, by comparing a group of affected individuals with a group of unaffected controls (Risch and Merikangas, 1996).There are two approaches to doing association studies. The "direct method" involves testing each putative causal variant for correlation with the disease (Risch 2000). At present, this approach is limited to sequencing the functional parts of candidate genes (selected on the basis of a previous functional or genetic hypothesis) for potential disease-associated candidate variants (Botstein and Risch 2003). Another one is "indirect method" (Collins et al 1997), which suggested that a set of sequence variants in the genome could serve as genetic markers to detect association between a particular genomic region and the disease, whether or not the markers themselves had functional effects. The search for the causative variants could then be limited to the regions showing association with the disease. Genetic epidemiology study tries to correlate the markers with phenotype to localize genetic factors susceptible to complex diseases (Weiss and Terwillger 2001), either by linkage or by linkage disequilibrium (LD).With recent advances in laboratory techniques and efforts to complex trait mapping, the amount of variation in the human genome, especially single nucleotide polymorphisms (SNPs), and the obsevered genotypic data have grown dramatically, which increase the...