What are genetic alterations and why do they occur?

What are genetic alterations?

As we know, the structure of DNA(1) is made up of segments called genes(2) that contain the exact coding of how a species should be phenotypically and what differentiates it through ourgenetic inheritance.

This happens because DNA works with a sequence that contains the exact information that allows a species to work perfectly and that make up the genotype of it. If this structure or its coding suffers an alteration even in a gene, it can have negative repercussions, including suffering from diseases.

These changes in structure and coding are called genetic alterations. Then, genetic alterations occur because they involve other factors such as environmental factors with the ability to modifythe original structure of DNA.

Note: At present, science has identified several genetic alterations that lead to diseases, which have been precisely located in the structure of the chromosome, for example, Down syndrome (3) which consists of an alteration of the number of chromosomes (4) in pair 21 of the human genome. (5)

Why do genetic alterations occur?

As mentioned earlier, the alteration in a single gene can change the instructions for making proteins, causing a mutation. Here are some of these causes:

1. Genetic factors

To highlight: This can happen due to exposure to some risk factors such as prohibited substances, radiation or drugs.

It is also possible that the alteration occurs during the transformation process from the zygote to the embryo , although the sexual cells do not present it.

2. Environmental factors

Environmental factors such as solar radiation, harmful substances such as drugs or alcohol, increase the probability that this type of error takes place and affects mainly during the cell division process, giving space for genetic alterations.

You should know: These genetic alterations affect only the cell in which the error has occurred and are not transmitted to the offspring.

What are the most common genetic alterations?

Below we briefly explain What the most common Most commonGenetic alterations are:

1. Genetic mutations

Note: These mutations are caused by the intervention of various factors, such as exposure to radiation or pollutants, which are associated with the development of diseases of genetic origin.

In this context, there are three types of genetic mutations:

• Molecular: They are mutations that affect the chemical constitution of genes , that is, the bases of DNA, affecting the production of the specific protein to be synthesized and altering its function within the organism.
• Chromosomal: In this case, the change affects a larger chromosome segment of the section of a gene and therefore also affects its structure.
• Genomic: Affects the entire genome, increasing the number of chromosome sets or reducing them to a single series, or affects the number of chromosomes individually, such as trisomy 21 or Down syndrome.

2. Polymorphisms

Genetic polymorphisms, whether chromosomal or DNA sequence, are responsible for the great variability and differentiationthat exists between individuals of the same species. This normally occurs in a single nucleotide of the DNA chain.

To highlight: In scientific terms, polymorphism is defined as: “Thesimultaneous existence in a population of genomeswith different alleles for a given locus” . (6)

These polymorphisms occur due to homologous recombination, chromosome segregation, mutations, duplications, and rearrangements.

In this sense, there are two types of polymorphisms:

• Those that occur in coding or gene regions: These polymorphisms can induce important changes in the phenotype of the individual, including diseases and are heritable.
• Those that occur in Non-coding or genic regions : They do not necessarily produce changes in the individual’s phenotype, nor do they have an impact on health, but they are present in the genetic material.

3. Genetic diseases

A genetic disease is a disorder that occurs at the cellular level and originates from an alteration in one or several genes in the DNA chain and this may or may not be hereditary .

You should know: The causes of genetic diseases originate from exposure to environmental factors that have the property of altering the structure and genetic code of the human genome.

At this point the following types of genetic diseases are distinguished:

• Single gene defects: In this case, genetic alterations occur in the DNA sequence of a single gene through a dominant, recessive, or X-linked pattern. Cystic fibrosis or thalassemia disease have this pattern of inheritance. (7)
• Chromosomal disorders: They are due to alterations in the structure or number of chromosomes, such as Down Syndrome or Turner Syndrome. (8)
• Multifactorial: In this case, they are those diseases that originate from the combination of multiple variants of genetic and environmental origin.

Key Conclusions

• Genetic alterations are changes in the structure and coding of DNA.
• These genetic alterations can give rise to diseases of genetic origin .
• Genetic alterations are manifested in the phenotype of the offspring.
• Genetic alterations are caused by the intervention of genetic and environmental factors.
• can occur .