( Sequence information from the...)SNPs Powerful Tools for Association Studies

Sequence information from the completed human genome projects vastly increased our understanding of the human genome. Empowered by the expanded availability of genomic information, genetic studies have become an increasingly effective tool for identifying factors that influence disease susceptibility.

Physical differences between individuals have a strong genetic component. The goal of genetic studies is to identify specific genetic profiles that are associated with a disease (or trait) of interest. Although accurate phenotyping is essential for successful genetic studies, the availability of biological tools for genetic analysis is also necessary. In this document, we will discuss the evolution of the markers used to profile genetic differences, as well as explore the multiple approaches used in modern-day genetic studies. This analysis will clarify why single nucleotide polymorphisms (SNPs) are powerful tools for studying complex diseases or traits.

1. The evolution of genetic markers in scientific research

Scientific advancements have resulted in a series of genetic markers with ever-increasing information content and resolution power. In the past 30 years, restriction fragment length polymorphisms (RFLPs), short tandem repeats (STRs), and SNPs have played significant roles in genetic research.

Restriction fragment length polymorphisms

RFLPs were the first genetic markers to be widely used in genetic mapping studies. To identify RFLPs, genomic DNA is digested into small pieces, averaging several kilobases (kb), by restriction enzymes that recognize specific sequences (i.e., restriction sites) in the genome. When genomic variation between individuals eliminates or adds a restriction site it causes a change in the length of the resulting restriction fragments that can be used as a genetic marker. Any change in the DNA has the potential to cause
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