Key Difference – SNP vs Mutation
DNA variations are prominent among individuals. Single nucleotide polymorphism (SNP) and mutation are two such variations that result in the nucleotide sequence differences in organisms. The key difference between SNP and mutation is that SNP represents a single nucleotide difference in DNA while mutation represents any change of DNA including single to many nucleotide differences. SNP is one kind of a mutation.
CONTENTS
1. Overview and Key Difference
2. What is SNP
3. What is Mutation
4. Side by Side Comparison – SNP vs Mutation
5. Summary
What is an SNP?
Single Nucleotide Polymorphism (SNP) is defined as a difference in a single nucleotide of a DNA at a particular location in the genome. In most individuals, the same base sequence can be present while some individuals may have a single nucleotide difference in the same location of the DNA. These are the SNPs which contribute to the phenotypic variations, variation in anthropometric characteristics, disease probability characteristics and responses to the environments. This is the most common genetic variation found among the people. It is assumed that in every 300 nucleotides, one SNP can be seen. This reveals that there are more than 10 million SNPs in the human genome. SNPs in human genome offer a resource for mapping complex genetic traits.
SNP is one type of a mutation known as point mutation. When SNP occurs within a gene or in the regulatory region of a gene, it affects the function of the gene by playing a greater influence on the disease. Most SNPs have no effect on health or development. Nevertheless, some of these genetic differences have proven to be very important in the study of human health. Researchers have found SNPs that may help to predict an individual’s response to certain drugs, susceptibility to environmental factors such as toxins, and risk of developing particular diseases.
Some well-known diseases such as sickle cell anaemia, β thalassemia and cystic fibrosis occur mainly due to SNPs. People show different susceptibility levels for a wide range of human diseases. It is primarily due to SNPs in the human genome. The severity of illness and how the body responds to treatments are also decided by the SNPs found in the human genome. For example, individuals with one base mutation in the APOE gene (apolipoprotein gene) show a higher risk of getting Alzheimer’s disease.
DNA sequencing will aid the identification of SNPs. Pyrosequencing is a high throughput sequencing technique which allows detecting allelic variations (SNPs) among multiple parallel sequences by creating unique sequences. The detection of single nucleotide polymorphisms by PCR is necessary for many types of genetic analysis, from mapping genomes to tracking specific mutations. SNPs which are located between genes are used as biological markers to identify and locate disease-causing genes.
Figure 1: SNP mutation where cytosine is replaced by thymine
What is a Mutation?
Mutation refers to any change in the DNA sequence. Mutations are caused by insertion of nucleotides, deletion of nucleotides, inversion of nucleotides, duplication of nucleotides and the rearrangement of nucleotides in DNA. These changes result in negative or positive effects on phenotypes, and some mutations are inherited by subsequent generations. Mutations are originated during the DNA replication or due to different environmental factors such as UV light, cigarette smokes, radiation, etc.
Small scale and large scale mutations are visible in DNA. Small-scale mutations occur due to deletions, insertions, duplications, single nucleotide differences, inversions, etc. Large-scale mutations occur due to deletions of larger areas, reproduction of number variations, deletion of genes, loss of gene copies, and movement of larger sections of DNA from the original position, etc. Mutations will result in the alteration of the gene structure that expresses wrong proteins. Sometimes mutations result in positive characteristics and good proteins. Mutations are important for evolution. Otherwise, the population might not be able to adapt to the changing and challenging environments. Therefore, mutations are considered as the driving force behind evolution. However, most mutations are neutral.
Figure 2: DNA Mutation
What is the difference between SNP and Mutation?
SNP vs Mutation |
|
| SNP is DNA variation due to single nucleotide difference in the DNA. | Mutation is a DNA variation due to any change occurred in the DNA sequence. |
| Changes | |
| This involves a single change in the DNA. | This includes single to many nucleotide changes. |
| Occurrence | |
| SNP is very common and present at a frequency of more than 1% in a population. | Mutations are very rare and are present at a frequency less than 1% of a population. |
Summary – SNP vs Mutation
A mutation is defined as any change occurred in a DNA sequence comparatively to the normal DNA sequence. These are the changes caused due to mistakes of DNA replication or the influence of the different environmental factors. Mutations happen via insertions, deletions, inversions, duplications and rearrangements of nucleotides. Gene mutations cause structural and functional changes in the genes, resulting in significant differences in the next generations. However, inherited diseases are rarely caused by mutations since inherited disease are often recessive. SNP is the single nucleotide variation in a particular DNA sequence among the individuals. In SNPs, only one nucleotide difference can be observed at a particular location of the sequence. SNP is also a kind of a mutation known as point mutation as it changes DNA by changing one nucleotide from the considering sequence.
Reference:
1. “What is a gene mutation and how do mutations occur? – Genetics Home Reference.” U.S. National Library of Medicine. National Institutes of Health, n.d. Web. 24 Feb. 2017
2. González, Pelayo, Antonio Díez-Juan, Eliecer Coto, Victoria Álvarez, Julian R. Reguero, Alberto Batalla, and Vicente Andrés. “A single-nucleotide polymorphism in the human p27 kip1 gene (-838C>A) affects basal promoter activity and the risk of myocardial infarction.” BMC Biology. BioMed Central, 02 Apr. 2004. Web. 24 Feb. 2017.
Image Courtesy:
1. “Single nucleotide polymorphism substitution mutation diagram – cytosine to thymine” By NHS National Genetics and Genomics Education Centre – Flickr (CC BY 2.0) via Commons Wikimedia
2. “DNA UV mutation” By NASA/David Herring – NASA, (Public Domain) via Commons Wikimedia