A genetic mutation either genetic alteration It is a certain change in the nucleotide sequence of the DNA of a living being, the product of a copy error of the genetic material during cell division, or as a result of external agents such as viral infections, exposure to ionizing radiation or certain substances. chemicals (called mutagens).
Genetic mutations are a daily part of life, and the vast majority do not have perceptible effects on daily life. However, they can also play a vital role in the appearance of congenital diseases, when their effects are somehow harmful to health; or they can be a key factor in the evolution and origin of new species, when they give individuals an adaptive improvement capable of being transmitted to their offspring. In summary, mutations are common biological events, but they can be very important.
The importance of mutations depends, first of all, on the place where they occur within the genetic chain of DNA. The latter must be understood as a set of instructions to produce a certain living being. Thus, if the mutation occurs outside of the active ingredient in a specific protein, it may have little or no effect; while if it appears in its central places it can drastically alter behavior and bring severe consequences.
Similarly, mutations may or may not be heritable. Those that take place in an individual and are not reflected in their sexual cells will be just a minor eventuality in the history of the species. On the other hand, if the mutation occurs in the sexual or reproductive cells, it will engender a new individual whose genome possesses the mutation as its own and, therefore, will transmit it, in turn, to its offspring, introducing changes in the genome of the species. .
Mutations can occur at three different levels of DNA:
- Molecular level mutations. They alter the atomic bases of genes, that is, the chemical bricks of which DNA is made. In these cases the change is usually local, short-range compared to the rest of the genetic information.
- Chromosomal mutations. They alter an entire segment of a chromosome, that is, a structure larger than a gene, which can alter or delete large chunks of genetic information.
- Mutations at the genomic level. They alter the individual’s genome as a whole, for example, by increasing or decreasing the number of chromosomes and, therefore, introducing radical changes in the individual’s genetic information.
Examples of Genetic Mutations
Some common examples of gene mutations are:
- Chromosome trisomy 21. This mutation, which causes the so-called Down syndrome, consists of the appearance of an extra copy of chromosome 21 in the genetic code. This causes significant changes in the embryonic development of the fetus and produces individuals with mild to moderate mental retardation, as well as very specific and recognizable physical features, such as a flattened face, short neck, protruding tongue, and a single crease in the palm of the hand. .
- cancer mutations. Cancer is a deadly disease that occurs when a group of cells begins to multiply uncontrollably, invading and disabling vital organs and spaces. This is the product of the appearance of certain specific mutations in the cell, which result in a cancer cell. Normally the body knows how to get rid of these types of harmful cells, but when mutations occur in a certain key range, cancer cells can pass for “healthy” to the body.
- Marfan’s syndrome. This genetic disease, which affects one in 5,000 people, is due to a mutation in the FBN1 gene linked to the formation of the fibrillin-1 protein, necessary for the production of connective tissue in the body. As a result, individuals with Marfan syndrome have very tall and long bodies, abnormally large hands and feet, and excessively flexible joints. Along with this, they have heart problems and scoliosis.
- Congenital insensitivity to pain. It is a strange genetic condition that afflicts one in 125 million people, and which consists of a mutation of the NTRK1 gene, responsible for producing nervous system proteins. As a result, individuals have a loss of the ability to feel pain, perceive temperatures, and the sense of touch. Along with this are numerous bone and neurological problems, such as osteomyelitis and bone deformities, which often require amputations.
- chronic lymphocytic leukemia. This disease, understood as a type of blood cancer, is due to the deletion (deletion) of part of the information on chromosome 13, as well as the involvement of chromosomes 11 and 17. This disease can exist silently throughout life and it usually manifests itself in the elderly, causing fatigue, swollen lymph nodes and capillary fragility, but luckily it can be treated.
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