First of all, single nucleotide polymorphisms, often called SNPs or pronounced “snips,” are a DNA sequence variation that occurs when a single nucleotide such as A, T, C, or G in the genome differs between members of a biological species or paired chromosomes in a human. The least common basis must have a SNP frequency of at least 1% of the population. An example of a SNP is the replacement of a C with a G in the nucleotide sequence AACGAT, thus producing the sequence AACCAT. When SNPs occur within a gene they create different variants or alleles of those genes. One of the most striking features of this problem is that the SNP region is found in the non-coding genome and in genes, specifically in both exons and introns. According to research, SNPs are found on average once every 300 nucleotides, so in total there are around 10 million SNPs in the human genome. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay The second thing that needs to be mentioned is the origin of polymorphisms. SNPs are created by point mutations that normally correspond to any single nucleotide change anywhere in the genome. Some cases may occur such as the replacement of one nucleotide with another or the deletion or addition of a single nucleotide. Single nucleotide polymorphisms are variations of one nucleotide at a very specific locus and have mainly two alleles at each locus. SNP and genome-wide association studies used to determine gene functions. Single nucleotide polymorphisms are very useful in helping us find this out. These are SNPs that are used to mark specific genotypes. SNPs act as chromosomal tags on specific regions of DNA. Therefore, it can be used to identify the location of genes on chromosomes. The noncoding regions near the genome are often the parts that contain single nucleotide polymorphisms, but in reality it could also be found within a gene, within a coding region of a gene. In general, it is right that adjacent to a gene that interests us. It's not in the gene itself. Therefore, there are only two varieties of alleles. SNPs have some influence on central nervous system phenotypes that match susceptibility to neurological disorders. For example, in Alzheimer's disease there is the APOE gene which is an important genetic determinant in the disease, encoding apolipoprotein E (ApoE). When two SNPs in this gene will create three common variants: APOE ?2, ?3 and ?4, which produce the corresponding proteins ApoE2, E3 and E4 and each variant has a risk with a different level of susceptibility to Alzheimer's disease APOE special ?4. Please note: this is just an example. Get a custom paper from our expert writers now. Get a Custom Essay We live in a world where there are many hidden dangers such as cancer. For some reason, SNPs in disease-related genes are now increasingly being used as candidates in the search for causative variations. Most SNPs have no effect on health or development. Some of these genetic differences have proven to be very important in the study of human health. Researchers have discovered SNPs that can help predict an individual's response to certain medications, susceptibility to environmental factors such as toxins, and risk of developing particular diseases. SNPs can also be used to trace the inheritance of disease genes within families. Future studies will work to identify SNPs associated with complex diseases such as diseases.