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

Which banding procedure is MOST helpful for determining if a deletion has occurred on chromosome 10?

1. G-banding

2. C-banding

3. FISH

4. Q-banding

The correct answer is: FISH

The most helpful technique for determining if a deletion has occurred on chromosome 10 is FISH (Fluorescence In Situ Hybridization). FISH allows for the detection of specific DNA sequences on chromosomes, making it particularly effective for identifying structural abnormalities such as deletions. This method utilizes fluorescent probes that bind to specific regions of the chromosome, providing a visual representation that can clearly indicate the presence or absence of particular segments of DNA. While other banding techniques like G-banding, C-banding, and Q-banding provide a general view of chromosomal structure and organization, they may not be as precise in identifying smaller deletions. G-banding, for example, can show larger chromosomal abnormalities, but it might not resolve fine deletions or subtle changes in chromosomal content. C-banding focuses primarily on the heterochromatin regions of chromosomes, which may not be directly useful in identifying deletions across various chromosomal areas. Q-banding does provide some level of visual differentiation of chromosomes but lacks the specificity offered by FISH for pinpointing particular gene regions that may be deleted. Thus, FISH's capability to visualize specific sequences on a chromosome makes it the preferred method for assessing deletions, particularly on chromosome 10 in this scenario