Future of Forensics
What are SNPs?
Single nucleotide polymorphisms, commonly known as SNPs, are genetic variation amongst the billions of people in the world. Of the 3.2 billion nucleotides in our genome, approximately 10 million are SNPs. These genetic variations are usually found between genes. SNPs substitute one nucleotide for another and each SNP location can have one version per nucleotide: adenine, thymine, guanine, and cytosine. Not all single-nucleotide changes are SNPs; in order to be classified as a SNP, at least two versions must occur in at least 1% of the SNP population.(Sources: What are Single Nucleotide Polymorphisms?, The Human Genome, and Making SNPs Make Sense)
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Locating SNPs
Scientists identify, catalog, and characterize SNPs using genomic and functional approaches.
Genomic Approaches
Several large genomic projects have been combined to identify and catalog all the SNPs from the entire human genome. In each project, scientists compare genomes of many individuals to find the genomic differences between each individual. (Source: Making SNPs Make Sense)
Functional Approaches
This approach is used more commonly amongst scientists because is mostly used to research a certain disease or drug response. The genes involved in diseases and drug response are controlled by a combination of genes. Scientists select genes known to cause the disease or drug response and examine them in people who have and don't have the disease or drug response. By studying DNA from various people, scientists can easily identify SNPs causing the disease or drug response. (Source: Making SNPs Make Sense)
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Are SNPs Point-Mutations?
Although point-mutations and SNPs sound like the same thing, they are actually quite different. A point-mutation is a change in DNA caused by a single nucleotide change, insertion, or deletion. SNPs are not point-mutations because the changed sequence must occur in at least 1% of the SNP population; the same point-mutation rarely
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occur more than once. Additionally, mutations are located within genes and can affect the function of the amino acid produced by the gene. However, SNPs are usually not found inside genes and do not affect the function of the amino acid that is produced by the gene. (Sources: Making SNPs Make Sense and Point Mutation)