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

What type of banding technique should be used if nonhomologous material is suspected on the q-arm of chromosome 16?

1. G-banding

2. C-banding

3. Q-banding

4. R-banding

The correct answer is: C-banding

To identify nonhomologous material on the q-arm of chromosome 16, C-banding is the preferred technique. C-banding specifically targets the centromeric regions and the heterochromatic regions of chromosomes, which allows for a clearer visualization of these areas. This is particularly useful in cytogenetics when dealing with complex rearrangements or identifying additional chromosomal material that may have nonhomologous origins. G-banding, while widely used, provides a general pattern of bands that represent regions of heterochromatin and euchromatin and does not specifically enhance the visibility of centromeric or heterochromatic areas as C-banding does. Q-banding utilizes fluorescent dyes, giving a different type of visual contrast that may not be as effective for identifying specific nonhomologous material when compared to the clarity provided by C-banding. R-banding, which highlights the reverse pattern to G-banding, also does not focus specifically on the heterochromatin adjacent to the centromere in the same way C-banding does. Thus, C-banding is the most suitable method for detecting and examining nonhomologous material on the q-arm of chromosome 16 due to its specialized approach to visualizing heterochromatic regions