Question

A 59 year old man is diagnosed with CML–chronic myelocytic leukemia. All of the following help to explain the genetic etiology of the CML EXCEPT?

1) a chromosomal structural defect called translocation occurs.
2) pieces of two chromosomes are exchanged.
3) a chromosomal aneuploidy defect called translocation occurs.
4) a short, defective chromosome called the Philadelphia chromosome develops.

Answer 1

The genetic cause of CML involves chromosomal translocation, most notably the development of the Philadelphia chromosome. Aneuploidy, which is an abnormal number of chromosomes, is not related to CML, making the third option incorrect.

Step-by-step explanation:

The genetic etiology of CML (chronic myelocytic leukemia) involves several key factors related to chromosomal abnormalities. However, one option given does not accurately describe the genetic cause of CML:

• A chromosomal structural defect called translocation occurs.
• Pieces of two chromosomes are exchanged.
• A chromosomal aneuploidy defect called translocation occurs. (This choice is incorrect because aneuploidy refers to an abnormal number of chromosomes, whereas translocation refers to a structural rearrangement.)
• A short, defective chromosome called the Philadelphia chromosome develops.

Therefore, the correct answer here is the third option, as translocations are structural changes and not related to aneuploidy (abnormal chromosome numbers).