Myelogenous leukemia is due to

Options

A. Complete loss of one chromosome of 21 st chromosome pair
B. Translocation of a part of chromosome number of 8 into chromosome 13
C. Deletion in long arm of chromosome 13
D. Deletion of long arm of chromosome 22 and its addition to chromosome 9.

Answer

### Step-by-Step Solution:

1. **Understanding Myelogenous Leukemia**: Myelogenous leukemia, specifically chronic myelogenous leukemia (CML), is a type of cancer that affects the blood and bone marrow. It is characterized by the overproduction of myeloid cells, which are a type of white blood cell.

2. **Identifying Causes**: The cause of myelogenous leukemia is often linked to genetic changes in the cells. One of the most common genetic abnormalities associated with CML is a specific chromosomal translocation.

3. **Chromosomal Translocation**: In CML, there is a translocation between chromosome 22 and chromosome 9. This means that a part of chromosome 22 is deleted and added to chromosome 9. This genetic alteration leads to the formation of the Philadelphia chromosome, which is a hallmark of CML.

4. **Evaluating the Options**:
- **Option A**: Complete loss of one chromosome of the 21st chromosome pair - Incorrect.
- **Option B**: Translocation of part of chromosome number 8 into chromosome 13 - Incorrect.
- **Option C**: Deletion in the long arm of chromosome 13 - Incorrect.
- **Option D**: Deletion of the long arm of chromosome 22 and its addition to chromosome 9 - Correct.

5. **Conclusion**: The correct answer is that myelogenous leukemia is due to the deletion of the long arm of chromosome 22 and its addition to chromosome 9.