Single Nucleotide Polymorphisms

– Summary:

Single nucleotide polymorphisms (SNPs) are a type of polymorphism that produces a variation in a single base pair.
They are the places in the genome, where people are different in a specific place.

There are works about, how single nucleotide polymorphisms, or SNPs (pronounced «snips»), in the human genome correlate with disease, with drug response, and other phenotypes.

– Discussion:

The type of polymorphism of SNPs can be detected by various methods and given their great biological importance, they have been used successfully in several studies.

One of these locations is found in about one out of every 1,100 letters of the code, meaning that there are roughly 4 to 5 million SNPs in a person’s genome.

In one person there may be a C (cytokine) and another may have a T (thymine), this being the most common SNP (2/3).

One of these variations must occur in at least 1% of the population to be considered a SNP. If it does not reach 1%, it is not considered a SNP and a specific mutation.

This is what is called a SNP. Most SNPs do not have much meaning, because they are in a part of the genome that does not have a critical function.

However, some of them confer a risk for a disease such as diabetes or heart disease, obesity, hypertension and psychiatric disorders, for example.

These are of great interest, because they provide data about why such diseases occur.

SNPs can be isolated from cDNA, messenger RNA, and ESTs.
An expressed sequence marker or EST (acronym in English: Expressed Sequence Tag) is a small subsequence of a transcribed nucleotide sequence (encoding a protein or not).

They can be used to identify genes to be transcribed and in gene discovery, and for sequence determination.
Complementary DNA (cDNA) is a double-stranded DNA molecule, in which one of its strands constitutes a sequence totally complementary to the messenger RNA from which it has been synthesized.

Single nucleotide polymorphisms:

It is the most common type of change in DNA or molecules within cells that contain genetic information.

Single nucleotide polymorphisms occur when a single nucleotide (a building block of DNA) is replaced by another.

These changes can cause illness and affect the body’s response to bacteria, viruses, drugs, and other substances.

The diversity of the genome within the same species makes each individual unique and unrepeatable, as well as the differential characteristics between individuals of the same species.

In a diploid cell, each locus is occupied by two alleles, one of maternal origin and the other of paternal origin, located on homologous chromosomes.

When polymorphisms affect somatic cells, non-reproductive cells are not transmitted to offspring, that is, they are not inherited (this is the case in most cancers).

Polymorphisms can have different functional significance, depending on whether they affect a coding region of the genome, a regulatory region or a non-coding region.

– Conclusions:

An example of these markers is the single nucleotide polymorphism of the beta-globin gene, which allows prenatal diagnosis of sickle cell disease.

They are used for clinical purposes such as the possibility of transplants, the genetic instability of tumors, etc.

They can also be used medically for the detection of susceptibility to pathological processes, especially in the prevention of complex diseases.
SNP, or single nucleotide polymorphisms, are responsible for a large part of the diversity of the human genome.

Although most of them do not directly cause diseases.
Sometimes they are located very close to mutations or polymorphisms involved in pathogenic processes, which makes them useful as genetic markers.


-Methods Mol Biol. 2009; 578: 3-22. doi: 10.1007 / 978-1-60327-411-1_1. SNPs: impact on gene function and phenotype. Barkur S Shastry.
-M Wolpin, Brian; Rizzato, Cosmeri (2014). «Genome-wide association study identifies multiple susceptibility loci for pancreatic cancer». Nature genetics 46: 994–1000. PMID 25086665.


SNP and diseases, SNP and tumors, SNP and diabetes, SNP and obesity, SNP and mental disorders, polymorphisms and SNP, SNP and cytokine, SNP and thymine, SNP and coding region, SNP and introns. SNP and y transplants.

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