What are the types of genetic mutations that exist?

What are genetic mutations?

A genetic mutation consists of thealteration of the structure or sequence of nucleotides of DNA (deoxyribonucleic acid), which can occur in a gene or in several genes of our genetic material. (1)

This alteration in the DNA strand makes it impossible to properly synthesize the protein or proteinsprecisely, through the process of “reading frame” that makes the ribosome of the mRNA (2). In this case, the function of the protein could change, affecting the system.

In general, a type of genetic mutationcan generate changes in thegenotypeandphenotypeof the individual, but more commonly it is reflected in the appearance of some genetic diseases.

Note: Some of these genetic mutationsthat alter human behavior are studied from the perspective ofbehavioral genetics.

What are the types of genetic mutations?

Below we describesthe different types of genetic mutations that have been discovered by science:

1. Gene mutations

Gene mutations or also called point mutations, are mutations that occur at the molecular level and affect the chemical constitution of genes and are divided into:

silent mutations

Silent mutations are base or nucleotide substitutions, which do not produce changes in the functionality of the amino acid or amino acids, when the altered messenger RNA (mRNA) is translated, and do not affect the composition of the synthesized protein. (3)

Polymorphisms

This type of mutation involves one of two or more variants of a particular DNA sequence in a single base pair, but they can also be much larger, involving long stretches of DNA. (4)

To highlight: Polymorphisms, whether chromosomal or DNA sequence, are responsible for the great differentiation that exists between living beings of the same species.

Substitution

Substitution is a type of mutation, in which One base pair is replaced by a different base pair in the DNA strand.

You should know: The term also refers to the substitution of an amino acid in a protein with a different amino acid, to cause a small change in the protein that is synthesized. (5)

insertion

In this type of mutation, it happens that one or more pairs of nucleotides are added to the DNA sequence. When the insertion is greater than one base pair, it may involve a fragment of the chromosome. (6)

Note: These insertions of additional genetic material into the DNA strand of the chromosome can affect the phenotype of the offspring, such as a birth defect.

2. Chromosomal mutations

Chromosomal mutations are those that affect a chromosome segment and therefore its structure. Below we describe the types of chromosomal mutations:

Deletion

Chromosomal deletion mutation is a type of genetic mutation in which DNA loses genetic material, from a single pair of nucleotides to an entire chromosome fragment. (7)

In this context, the deletion of a base pair in the DNA can cause a severe congenital defect in the phenotype of the offspring.

To highlight: In specific cases, the deletions are so long (the loss of genetic material) that they can compromise an entire gene or several contiguous genes.

Duplication

In this type of mutation there is a segment of DNA that is copied one or several times within the same sequence, altering the formation of the amino acid chain and the function of the protein. (8)

You should know: In this way, the reading frame in the ribosome is altered to form the protein or insert extra amino acids, which may be unsuitable for their purpose.

Investment

Chromosomal inversion is a type of genetic mutation, where a structural change occurs by which a chromosomal segment changes direction within the chromosome itself.

Note:This investment occurs whena chromosome suffers two breaks and is reconstituted with the same segment that was broken, but inverted and usually does not produce phenotypic abnormalities.

Translocation

In this case of chromosomal mutation, a change oflocation occurs from thepart of one chromosome to another chromosome and is considered an abnormality, because one chromosome breaks and a part of it joins a different chromosome. (9)

To highlight: These types of mutations give rise to diseases such as acute myeloid leukemia, which may not manifest from birth.

3. Genomic mutations

Genomic mutations are those that affect the whole genome, that is, they increase or reduce the number of chromosome sets or affect the number of individual chromosomes. In this group are:

Euploidia

In this case of genomic mutation, a variation of complete sets of chromosomes occurs .

For example, in the case of human beings, a set of chromosomes can disappear and a cell can have only 23 chromosomes instead of 46, and if this happens during fertilization, the development of the fetus cannot be carried out and there is a abortion.

aneuploidy

In this case, a variation of the set of chromosomes occurs and only in one of the chromosomes.

while it is normal to have only two copies of this chromosome.

Trisomy

A trisomy is a genetic mutation, in which a person has three copies of a chromosome instead of two in any of its pairs.

Note: This condition causes Very serious birth defects , from the human phenotype to very serious genetic diseases.

Key Findings

• Genetic mutations consist of alterations in the structure or sequence of nucleotides in DNA.
• These mutations can occur in in one gene or in several genes of our genetic material.
• Genetic mutations make proper synthesis of the protein or proteins impossible for cells.
• Genetic mutations are classified into gene mutations, chromosomal mutations, and genomic mutations.