American Society for Clinical Pathology (ASCP) Technologist in Cytogenetics certification (ASCP CG) Practice Test

What banding technique would confirm a suspected inversion of chromosome 9?

1. C-banding

2. Q-banding

3. R-banding

4. G-banding

The correct answer is: C-banding

C-banding is particularly useful for identifying and analyzing structures of heterochromatin, especially on chromosomes 1, 9, and Y. Inversions can often disrupt normal banding patterns, and C-banding highlights the centromeric heterochromatin, making the confirmation of inversions more straightforward. On the other hand, Q-banding, R-banding, and G-banding provide different types of information about the chromosomes. Q-banding utilizes fluorescent dyes to highlight specific regions, while R-banding produces a reverse pattern to G-banded chromosomes, enhancing the visibility of certain regions, particularly on the terminal ends. G-banding, the most commonly used technique, also provides a detailed visualization by producing a specific pattern of light and dark bands for comparative analysis. However, these techniques may not provide the clarity needed for specifically confirming the nature of inversions on chromosome 9, making C-banding the most appropriate choice.