What is a SNP?
SNP stands for single nucleotide polymorphism. Our genetic code, or DNA, is made up of long strings of nucleotides represented by A, T, C, G. These letters are arranged in a very specific order. At some places in the genetic code people have different letters (one person may have a T, while another person may have a G). A particular variation, when known to be common throughout the population, is called a SNP (pronounced “snip”). We now know that having one letter in place of another can increase an individual’s risk for certain diseases.
The acronym SNP stands for Single Nucleotide Polymorphism. This refers to a particular nucleotide (or “base”) in a DNA sequence that is variable within a species (or between related species). For example, at a certain position in a DNA sequence there may be a C (cytosine) present in some individuals but a T (thymine) present in others. SNPs represent the most basic form of genetic polymorphism. There are tens of millions of SNPs present in the genome of a typical organism. However, usually only a very small subset of these will be developed into genetic markers (SNP markers). Although it is somewhat confusing, the term “SNP” can refer both to a particular polymorphism in the genome (for which a genetic marker may or may not have been developed) or to a marker that has been developed to evaluate (or “genotype”) a particular SNP polymorphism.
A Single Nucleotide Polymorphism (SNP) is the variation of a single base pair in the DNA sequence between either the members of a species or between the paired chromosomes of an individual. These polymorphisms may affect how organisms develop diseases and respond to chemicals and drugs. SNPs are, therefore, of great value in biomedical research and drug development. SNP detection and genotyping can be used to explain and diagnose many diseases, to study the variation in drug responses, to establish the origin of biological material and to study the relatedness between individuals. Sequencing is a popular method for SNP genotyping but this method is more expensive and time consuming as compared to the microarray based methods. DNA microarrays represent a technological platform that enables SNP genotyping. Microarrays allow simultaneous testing of up to hundreds of SNPs.
SNP is usually the abbreviation for single nucleotide polymorphism. Of the 3 billion base pairs that the human genome contains, two people picked at random will differ once about every 1000th base. This forms the basis of the genetic variability that is the focus of our work. While most of the millions of SNPs found in the human genome have no known functional effect, some do and we are studying several of these so-called functional polymorphisms in the domain of psychiatry and cognition to understand how they affect brain function. Ironically (?), one of our current methodological projects is to go beyond SNPs and develop methods to image the effect of haplotypes, which are combinations of SNPs inherited together that may contain more information about the underlying genetic structure.
A SNP, or Single Nucleotide Polymorphism, is a change in your Y-DNA sequence at a location other than those in the 12, 25, 37, and 67 marker tests. SNPS are unique to specific haplogroups so SNP tests such as the Backbone and Deep SNP tests are used to identify haplogroups and their subclades respectively. Haplogroups, defined by SNP’s are the branches of the tree of mankind.
