What is the Difference Between Reciprocal and Robertsonian Translocation

The main difference between reciprocal and Robertsonian translocation is that reciprocal translocation involves the exchange of genetic material between non-homologous chromosomes, while Robertsonian translocation occurs when two acrocentric chromosomes fuse together, resulting in the formation of a single, larger chromosome and loss of two smaller satellite chromosomes.

Reciprocal translocation and Robertsonian translocation are two different types of chromosomal rearrangements.

Key Areas Covered

1. What is Reciprocal Translocation
     – Definition, Characteristics, Consequences
2. What is Robertsonian Translocation
     – Definition, Characteristics, Consequences
3. Similarities Between Reciprocal and Robertsonian Translocation
     – Outline of Common Features
4. Difference Between Reciprocal and Robertsonian Translocation
     – Comparison of Key Differences

Key Terms

Reciprocal Translocation, Robertsonian Translocation

Difference Between Reciprocal and Robertsonian Translocation - Comparison Summary

What is Reciprocal Translocation

Reciprocal translocation is a chromosomal abnormality involving genetic material exchange between two non-homologous chromosomes. It is a significant genetic rearrangement that can have various implications for individuals who carry this type of translocation. Reciprocal translocation occurs when two chromosomes break at specific points and exchange segments of genetic material. This exchange can involve large or small segments of the chromosomes and occur between any two chromosomes. It is important to note that reciprocal translocation is a balanced rearrangement, meaning that, overall, no genetic material is gained or lost.

The causes of reciprocal translocation can vary. In some cases, it may occur spontaneously during the formation of gametes in one of the parents, leading to the translocation being passed on to their offspring. In other instances, reciprocal translocation can result from errors during DNA replication or chromosomal recombination processes in early development. Exposure to certain environmental factors, such as radiation or certain chemicals, may also increase the risk of developing reciprocal translocation.

Compare Reciprocal vs. Robertsonian Translocation - What's the difference?

Effects of Reciprocal Translocation

One of the key genetic consequences of reciprocal translocation is the disruption of normal gene function. The breakpoints of the translocated chromosomes can result in the repositioning of genes altering their regulation and expression patterns. This can lead to abnormal protein production, affecting various cellular processes and potentially causing health issues. The severity of the consequences depends on the specific genes involved in the translocation and the size of the exchanged segments.

The impacts of reciprocal translocation on human health can vary greatly. Some individuals with reciprocal translocations may exhibit no symptoms or health problems. They are considered carriers of translocation as they possess the rearranged chromosomes but do not experience any adverse effects themselves. However, these carriers have an increased risk of potentially passing the translocation on to their offspring, resulting in health issues for the next generation.

What is Robertsonian Translocation

Robertsonian translocation is a type of chromosomal rearrangement that involves the fusion of two acrocentric chromosomes at their centromeres. It occurs when two specific types of chromosomes, called acrocentric chromosomes, fuse together. Acrocentric chromosomes such as chromosomes 13, 14, 15, 21, and 22 have centromeres located near one end, resulting in shorter arms. During the process of Robertsonian translocation, the long arms of two acrocentric chromosomes break, and the fused centromeres form a single, larger chromosome. As a result,  two smaller satellite chromosomes are typically lost in subsequent cell divisions.

Reciprocal vs Robertsonian Translocation

 

Spontaneous occurrence of Robertsonian translocation during gamete formation in one of the parents can result in the translocation being inherited by their offspring. Environmental factors such as radiation exposure may also increase the risk of developing Robertsonian translation. Additionally,  individuals with Robertsonian translocation have a higher chance of having a child with an unbalanced chromosomal rearrangement, which can occur during meiosis.

The most well-known example of Robertsonian translocation involves chromosome 21. Down syndrome, also known as trisomy 21, is often associated with the presence of an extra copy of chromosome 21. However, in a small percentage of cases, Down syndrome can result from a specific type of Robertsonian translocation involving chromosome 21. In these cases, one of the parents carries the translocation, where an extra copy of chromosome 21 is fused with another acrocentric chromosome. When this translocation is passed on to the offspring, it can result in the individual having two copies of chromosome 21 plus an additional copy of chromosome 21, leading to Down syndrome.

Similarities Between Reciprocal and Robertsonian Translocation

  • Reciprocal translocation and Robertsonian translocation involve structural changes in the chromosomes.
  • Both types of translations involve specific breakpoints where the chromosomes break and rejoin.
  • They lead to genetic consequences.

Difference Between Reciprocal and Robertsonian Translocation

Definition

Reciprocal translocation involves the balanced exchange of genetic material between non-homologous chromosomes, resulting in the exchange of segments of genetic material between the two chromosomes. Robertsonian translocation, on the other hand, occurs when two acrocentric chromosomes fuse together at their centromeres, resulting in the formation of a single, larger chromosome and the loss of two smaller satellite chromosomes.

Chromosomal Involvement

In reciprocal translocation, two non-homologous chromosomes exchange segments of genetic material, leading to a balanced exchange between the chromosomes. On the other hand, Robertsonian translocation occurs when two specific types of chromosomes, known as acrocentric chromosomes, fuse together at their centromeres. This fusion results in the formation of a larger chromosome and the loss of two smaller satellite chromosomes.

Genetic Consequences

Reciprocal translocation can have varying genetic consequences depending on the breakpoints involved. It can lead to the rearrangement or repositioning of genes, potentially disrupting their normal function. Reciprocal translocations can be balanced, where there is no net gain or loss of genetic material, or unbalanced, resulting in chromosomal imbalances in offspring. On the other hand, Robertsonian translocation generally does not cause major phenotypic effects in carriers as there is no net gain or loss of genetic material. Still, there is a risk of unbalanced chromosomal rearrangements in offspring due to the presence of extra or missing genetic material due to the loss of the two smaller satellite chromosomes.

Conclusion

Reciprocal translocation and Robertsonian translocation are two different types of chromosomal rearrangements. The main difference between reciprocal and Robertsonian translocation is that reciprocal translocation involves the exchange of genetic material between non-homologous chromosomes, while Robertsonian translocation occurs when two acrocentric chromosomes fuse together, resulting in the formation of a single, larger chromosome and loss of two smaller satellite chromosomes.

Reference:

1. “Reciprocal Translocation – An Overview.” Science Direct.
2. “Robertsonian Translocation – An Overview.” Science Direct.

Image Courtesy:

1. “Translocation-4-20” By National Human Genome Research Institute -(Public Domain) via Commons Wikimedia 
2. “Robertsonian translocation” By Original from Database Center for Life Science (DBCLS)Derivative by Mikael Häggström, M.D. (CC BY 4.0) via Commons Wikimedia

About the Author: Hasini A

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