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

What technique should be used to analyze chromosomes when satellites are suspected?

1. G-banding

2. NOR banding

3. FISH

4. Q-banding

The correct answer is: NOR banding

When analyzing chromosomes where satellites are suspected, NOR banding is the most appropriate technique to use. NOR banding specifically targets the nucleolar organizer regions (NORs) on chromosomes, which are areas involved in ribosomal RNA synthesis. These NORs are associated with the presence of satellites, which are repetitive DNA sequences located on the acrocentric chromosomes. By employing NOR banding, one can visualize the nucleolar organizer regions and identify the presence and structure of satellite DNA, making it ideal for cases where there are suspicions of abnormal satellite arrangements or numbers. In contrast, G-banding is commonly used for general chromosome analysis and karyotyping, but it does not specifically highlight the nucleolar organizer regions. FISH (Fluorescence In Situ Hybridization) can provide more targeted information and is useful for detecting specific DNA sequences, but it does not inherently focus on the assessment of satellites associated with nucleolar organizers. Q-banding, while useful for visualizing certain chromosome features, does not specifically address the presence of satellite DNA and NORs as effectively as NOR banding.