Connection+of+DNA+Microarrays+to+HapMap+and+GWAS

HapMap (single nucleotide polymorphisms)

HapMap will describe the common patterns of human DNA sequence variation. -Most common diseases, such as diabetes, cancer, heart disease, stroke, depression and asthma, are affected by many genes and environmental factors.

Although any two unrelated people share about **99.9 percent** of their DNA sequences, the remaining **0.1 percent** is important because it contains the genetic variants that influence how people differ in their risk of disease or response to drugs.

Discovering the DNA sequence variants that contribute to disease risk offers one of the best opportunities for understanding the complex causes of many common diseases in humans.

Single Nucleotide Polymorphisms is when one base pair is mutated or changed into another base pair. This affects the whole sequence.

What is a haplotype?
About 10 million SNPs exist in human populations. A set of associated SNP alleles in a region of a chromosome is called a haplotype. Most chromosome regions have only a few common haplotypes, which account for most of the variation from person to person in a population. A chromosome region may contain many SNPs, but researchers can use only a few "tag" SNPs to obtain most of the information on the pattern of genetic variation in the region. The HapMap describes the common patterns of genetic variation in humans. It includes the chromosome regions with sets of strongly associated SNPs, the haplotypes in those regions and the SNPs that tag those haplotypes. It also notes the chromosome regions where associations among SNPs are weak.

Researchers trying to discover the genes that affect a disease, such as diabetes, will compare a group of people with the disease to a group without the disease. If the haplotypes differ in the SNP regions, then the person may have the disease.

One way to look at these regions is for researchers to genotype 10 million SNPs. This is too expensive, so they use the technology of MICROARRAYS!

GWAS (Genome wide association studies)

-A genome-wide association study is an approach that involves scanning markers across the **complete** sets of DNA, or genomes, of many people to find genetic variations associated with a particular disease.

After identifying genetic make-up researchers can use the information to develop better strategies to detect, treat and prevent the diseases.

This is useful in finding genetic variations that contribute to common, complex diseasessuch as asthma, cancer, diabetes, heart disease and mental illnesses.

Microarrays are used to determine the diseases by analysis.