Single nucleotide polymorphisms

Single nucleotide polymorphisms (SNPs, pronounced "snips") are the most common type of genetic variation among people. Each SNP represents a difference in a single DNA base, nucleotide, among individuals. SNPs occur normally throughout a person’s DNA. They occur once in every 300 nucleotides on average, which means there are roughly 10 million SNPs in the human genome. These variations occur in the DNA sequence and are found in the genes that make up the genome. They can act as biological markers, helping scientists locate genes that are associated with disease.

Characteristics

SNPs are typically classified into different types based on their effect on the proteins they encode. There are synonymous SNPs, which do not change the amino acid sequence of the protein, and non-synonymous SNPs, which do change the amino acid sequence of a protein. Non-synonymous SNPs are further divided into missense SNPs, which change one amino acid to another, and nonsense SNPs, which change an amino acid to a stop codon, potentially truncating the protein.

Importance in Research and Medicine

In medical genetics, SNPs have been linked to various genetic disorders and are also crucial in pharmacogenomics, the study of how genes affect a person's response to drugs. This is because certain SNPs are capable of influencing drug efficacy and toxicity, thereby guiding personalized medicine.

Role in Genetic Diversity

SNPs contribute to the genetic diversity among humans, influencing a variety of traits such as appearance, metabolism, and susceptibility to diseases. They are also used in forensic science to assist in identity verification and in anthropology to understand human evolutionary history.

Detection and Analysis

The identification of SNPs is performed through various genotyping techniques, including DNA sequencing and DNA microarrays, which allow for the analysis of thousands of SNPs at once. The data obtained from SNP genotyping can be used in genome-wide association studies (GWAS), which examine SNP variations across many individuals to find associations with diseases and other traits.

Ethical and Social Considerations

The study of SNPs raises ethical and social issues, particularly concerning privacy, discrimination, and the implications of genetic testing. It is important to address these issues with clear policies and informed consent.

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