A translocation is called ‘balanced’ if?
**Core Concept**
A balanced translocation is a type of chromosomal abnormality where a part of a chromosome breaks off and attaches to a different chromosome, but without any net loss or gain of genetic material. This occurs when the same segments of chromosomes are exchanged between two non-homologous chromosomes.
**Why the Correct Answer is Right**
In a balanced translocation, the genetic material is conserved, and there is no loss or gain of genetic information. This is because the segments of chromosomes exchanged are equal in size and contain the same genetic material. As a result, the individual with a balanced translocation is usually asymptomatic and does not exhibit any adverse effects. However, they are at an increased risk of passing on the abnormality to their offspring, who may be affected if the translocation is unbalanced.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because an unbalanced translocation involves a loss or gain of genetic material, which can lead to various health problems.
**Option B:** Incorrect because a Robertsonian translocation involves the fusion of two acrocentric chromosomes, resulting in a loss of genetic material.
**Option C:** Incorrect because a reciprocal translocation involves the exchange of segments between two non-homologous chromosomes, which can be balanced or unbalanced.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that balanced translocations are usually asymptomatic in the affected individual but can increase the risk of miscarriage, infertility, and birth defects in offspring.
**Correct Answer: C. A reciprocal translocation involving the exchange of segments between two non-homologous chromosomes.**