Difference Between Inversion and Translocation

Key Difference – Inversion vs Translocation
 

In the context of genetics, chromosomal rearrangement is a kind of abnormality that deviated from the native structure of the chromosomes. Some rearrangements create mutations that are lethal and lead to deleterious diseases such as cancers, syndromes etc. There are different types of chromosomal rearrangements namely deletions, inversions, translocations, duplications etc. In all these rearrangements, DNA double-strand breaks from two different locations and separates from the original chromosome. Then the broken fragment rejoins with the same chromosome or with a different chromosome to produce new chromosomal gene arrangement. Different factors cause these types of double-strand breaks. One factor is ionizing radiation that includes energetic X rays and gamma rays.  Inversion is a rearrangement in which broken double-stranded DNA fragment flips in 180 degrees and rejoins in the same chromosome at the same point. Translocation is another type of rearrangement in which broken double-stranded fragment of one chromosome joins at a new position of the non-homologous chromosome. The key difference between inversion and translocation is inversion occurs on the same chromosome, and it does not change the location while the translocation occurs between non-homologous chromosomes and it changes the location.

CONTENTS

1. Overview and Key Difference
2. What is Inversion
3. What is Translocation
4. Similarities Between Inversion and Translocation
5. Side by Side Comparison – Inversion vs Translocation in Tabular Form
6. Summary

What is an Inversion?

Invasion is a type of chromosomal rearrangement that causes new gene arrangement in the native chromosome. Due to different causes, double-stranded DNA sequences break at two points creating broken fragments.  Then a broken sequence flips in 180 degrees and rejoins at the same location. In other words, a broken fragment of a chromosome rejoins within the same location in the reversed end to end manner. This creates an abnormality in the gene arrangement of the chromosome.

Inversion does not cause the loss of genetic information. It simply rearranges the gene order or the gene sequence. There are two types of inversions namely paracentric and pericentric inversions. A paracentric inversion occurs in one arm of the chromosome without involving the centromere. Both arms of the chromosome break including the centromere during the pericentric inversion.

Inversions do not cause harmful effects since DNA repair mechanisms work easily to repair these types of rearrangements. And also inversions simply rearrange the gene sequences without creating losses or extra sequences.

What is a Translocation?

Translocation is a type of chromosomal rearrangement that occurs between non-homologous chromosomes. Broken segments are exchanged between two nonhomologous chromosomes. It creates two chromosomes that are genetically different from the native chromosomes. Reciprocal and Robertsonian are two types of translocations. Reciprocal translocation is the exchange of broken DNA segments between two non-homologous chromosomes. It does not cause loss or gain of genetic material. Hence it is a type of balanced rearrangement.

During the Robertsonian translocation, long arms of the two acrocentric chromosomes fuse with each other. Short arms can be lost. Hence, it is a type of imbalanced chromosomal rearrangement. Compared to the Robertsonian translocation, reciprocal translocation is a common type of chromosomal rearrangement. Some translocations are inherited while some newly occur. Certain translocations cause diseases such as cancer, Down syndrome, infertility and XX male syndrome.

What are the Similarities Between Inversion and Translocation?

• Inversion and Translocation are two types of chromosomal abnormalities.
• Both types cause chromosomal rearrangement.
• Inversions and translocations are resulted due to double-strand
• Both inversions and translocation can occur in the genetically balanced manner.

What is the Difference Between Inversion and Translocation?

Summary – Inversion vs Translocation

Inversion and translocation are two types of chromosomal abnormalities caused due to double-strand breaks. During the inversion, a fragment of chromosome breaks at two points and flips in 180 degrees and joins again with the chromosome. Translocation is the exchange of broken segments of chromosomes between non-homologous chromosomes. An inversion occurs within the same chromosome. Translocation occurs between non-homologous chromosomes. This is the difference between inversion and translocation.

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Reference:

1.Griffiths, Anthony JF. “Chromosomal Rearrangements.” Modern Genetic Analysis., U.S. National Library of Medicine, 1 Jan. 1999. Available here
2.Griffiths, Anthony JF. “Translocations.” An Introduction to Genetic Analysis. 7th edition., U.S. National Library of Medicine, 1 Jan. 1970. Available here

Image Courtesy:

1.’Phase variation site specific recombination – inversion’ By Marjan W. van der Woude and Andreas J. Baumler – Clinical Microbiology Reviews, (CC BY 3.0) via Commons Wikimedia 
2.’Translocation-4-20’By Courtesy: National Human Genome Research Institute, (Public Domain) via Commons Wikimedia