How do polymorphisms help with dna identification

Called a single nucleotide polymorphism, or SNP pronounced snip , scientists are studying how SNPs in the human genome correlate with disease, drug response, and other phenotypes. Polymorphism, by strict definitions which hardly anybody pays attention to anymore, is a place in the DNA sequence where there is variation, and the less common variant is present in at least one percent of the people of who you test.

That is to distinguish, therefore, polymorphism from a rare variant that might occur in only one in 1, people. A polymorphism, it has to occur in at least one in people. Polymorphisms could be not just single-letter changes like a C instead of T. Most commonly, these variations are found in the DNA between genes. They can act as biological markers, helping scientists locate genes that are associated with disease.

Most SNPs have no effect on health or development. Some of these genetic differences, however, have proven to be very important in the study of human health. SNPs can also be used to track the inheritance of disease genes within families. Future studies will work to identify SNPs associated with complex diseases such as heart disease, diabetes, and cancer.

The influence of genetic factors on the response of a drug is a known fact. Polymorphic STRs, together with SNPs and CNVs, can explain variability in response to pharmacotherapy because of their prevalence in the human genome and their functional role as regulators of gene expression and its applications. Pharmacogenetics is the study of the influence of genetics factors on drug response and metabolism.

The science of pharmacogenetics when applied can be used to evade adverse drug reactions, predict toxicity and therapeutic failure, and refine therapeutic efficiency and improve clinical outcomes [ 53 ]. This uniqueness in each individual is the basis of human identification at the DNA level, forensic identification, determination of genetic variation, determination of family relationship, and one important instance is identifying good genetic matches for organ or marrow donation.

When first described in by British scientist Alec Jeffreys, the technique used was minisatellites; these sequences are unique to each individual, with the exception of identical twins.

Initially, forensic medicine used minisatellite testing; however, this method requires a large amount of material and yield low-quality results especially when only little amount of materials are available. Nowadays, in most forensic samples, the study of DNA is usually performed by microsatellite analysis. Among others, the microsatellite DNA marker has been the most widely used, due to its easy use by simple PCR, followed by a denaturing gel electrophoresis [ 40 ].

Each person has some STRs that were inherited from the father and some from mother, useful in paternity testing but however no person has STRs that are identical to those of either parent. Genomic and mitochondrial are two types of DNA which are used in forensic sciences.

The genomic DNA is found in the nucleus of each cell in the human body and represents a DNA source for most forensic applications. Mitochondrial DNA mt DNA is another source of material that can be used; various biological samples such as hair, bones, and teeth that lack nucleate cellular materials can be analyzed with mt DNA [ 43 , 55 ].

DNA typing becomes the method of choice for engraftment monitoring, donor cells are examined by following donor polymorphisms in the recipient blood and bone marrow. Although RFLP can efficiently differentiate donor and recipient cells, the detection of RFLP requires the use of southern blot methods, which is too labor intensive and has limited sensitivity for this application, in comparison with small minisatellites or microsatellites that are easily detected by PCR amplification, because of increased rapidity and the 0.

Sensitivity can be raised to 0. Single nucleotide polymorphisms SNPs have become an important application in the development and research of genetic diseases or other phenotypic traits. Haplotypes can have stronger correlations with diseases or other phenotypic effects compared with individual SNPs and may therefore provide increased diagnostic accuracy in some cases. Polymorphic tandem repeated sequences have emerged as important genetic markers and initially, variable number tandem repeats VNTRs were used in DNA fingerprinting; in recent years, evidence has been accumulated for the involvement of VNTR repeats in a wide spectrum of pathological states.

The new global CNV map will transform medical research in four main areas: detection for genes underlying common diseases, study of familial genetic conditions, exclude variation found in unaffected individuals, helping researchers to target the region that might be involved and the data generated will also contribute to a more accurate and complete human genome reference sequence used by all biomedical scientists.

About CNVs were detected in each genome tested with the average size being , bases an average gene is 60, bases. With advanced molecular technologies more CNVs will be discovered and more DNA samples from worldwide populations are examined. Recently, there has been substantial progress in understanding genome content which centered on protein-coding genes which considered a functional DNA sequence moving away for many discoveries, many repeat families, and various copy number variations that play an important role in genome structure, evolution, and diversity.

Additional efforts are being placed to develop strategies that would overcome the obstacles in alignment next-generation sequencing data. New long-read sequencing approaches are needed to meet this challenge. Other important applications of genetic polymorphism knowledge are improving health care through gene therapy, discovery of new drugs and drug targets, and upgradation of the discovery processes with advanced technologies.

Advances in molecular technologies, DNA sequencing technology, and microarray, coupled with novel, efficient computational analysis tools, have made it possible to analyze sequence-based experimental data, more discoveries, and development at a rapid rate. Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3.

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Downloaded: Keywords copy number variations genetic polymorphism microsatellite minisatellite molecular markers single nucleotide polymorphisms SNPs variable number tandem repeats VNTRs. Polymorphic repetitive sequences DNA repeats can be classified as interspersed repeats or tandem repeats. Structural and copy number variations Structural and copy number variations CNVs are another frequent source of genome variability [ 6 , 19 , 20 ].

Single nucleotide polymorphisms Single base pair change leads to single nucleotide variant, probably accounting for many genetic conditions caused by single gene or multiple genes. Microsatellites short tandem repeats Microsatellites are short tandem repeats STRs , repeat units, or motifs of less than 10 bp; because of high variability, microsatellite loci are often used in forensics, population genetics, and genetic genealogy.

Restriction fragment length polymorphism with southern blot DNA digestion with restriction enzyme endonuclease cuts DNA at a specific sequence pattern known as a restriction endonuclease recognition site.

Polymerase chain reaction In-vitro amplification of particular DNA sequences with the help of specifically chosen primers and DNA polymerase enzyme is done. Genomic array technology Genomic array technology is a type of hybridization analysis allowing simultaneous study of large numbers of targets or samples. Sequencing Since technologies for rapid DNA sequencing have become available they are now widely used. Mapping human diseases and risk prediction Genetic mapping and linkage: The mapping of the human genome has made possible to develop a haplotype map in order to better define human SNV variability.

Quantitative trait loci mapping, candidate genes, and complex traits The identification of genes affecting complex trait is a very difficult task. Pharmacogenetics Individual response to a drug is governed by many factors such as genetics, age, sex, environment, and disease.

DNA typing and engraftment monitoring DNA typing becomes the method of choice for engraftment monitoring, donor cells are examined by following donor polymorphisms in the recipient blood and bone marrow.

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