**Core Concept**
Cytogenetic abnormalities refer to changes in the number or structure of chromosomes. These abnormalities can be classified into several types, including numerical abnormalities (e.g., aneuploidy), structural abnormalities (e.g., translocations, deletions), and changes in ploidy (e.g., polyploidy). The question is asking about cytogenetic abnormalities where no change in genetic material occurs.

**Why the Correct Answer is Right**
The correct answer is a **deletion**. A deletion is a type of cytogenetic abnormality where a portion of a chromosome is lost. Since a deletion involves the loss of genetic material, it is not an example of a cytogenetic abnormality where no change in genetic material occurs. In contrast, a **translocation** is a type of cytogenetic abnormality where a portion of a chromosome breaks off and attaches to another chromosome. A **duplication** is a type of cytogenetic abnormality where a portion of a chromosome is copied, resulting in an extra copy of the genetic material. A **polyploidy** is a type of cytogenetic abnormality where the number of chromosomes in a cell changes, resulting in an abnormal number of chromosomes.

**Why Each Wrong Option is Incorrect**
**Option A:** A translocation involves the movement of genetic material from one chromosome to another, resulting in a change in genetic material.
**Option B:** A duplication involves the copying of a portion of a chromosome, resulting in an extra copy of the genetic material, which is a change in genetic material.
**Option C:** Polyploidy involves a change in the number of chromosomes in a cell, resulting in an abnormal number of chromosomes, which is a change in genetic material.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that cytogenetic abnormalities can be classified into several types, and each type has distinct characteristics. Understanding the differences between these types is crucial for accurate diagnosis and management of genetic disorders.

**Correct Answer:** C. Polyploidy.