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

Which of the following indicates that there is a problem with chromosome staining if they appear indistinct?

1. The exposure time is too long

2. The cells are over-fixed

3. The stain is improperly diluted

4. The trypsin treatment is ineffective

The correct answer is: The trypsin treatment is ineffective

The indication that there is a problem with chromosome staining when chromosomes appear indistinct can indeed be associated with ineffective trypsin treatment. Trypsin is used in preparing chromosomes for staining by digesting the proteins that could interfere with the staining process. If trypsin treatment is ineffective, it may fail to adequately expose the chromatin for the staining solution to bind properly, which leads to indistinct or poorly defined chromosomal banding patterns. The effectiveness of trypsin treatment is crucial in cytogenetics; it affects the resolution of chromosome features. When the digestion is insufficient, the resulting banding may appear blurred or indistinct, indicating poor quality in the staining process and ultimately affecting the interpretation of the chromosome analysis. This can lead to diagnostic issues, as clear and distinct chromosome banding is essential for identifying structural and numerical abnormalities. Other factors can affect staining quality as well, like over-fixing of the cells or improper dilution of the stain, but ineffective trypsin treatment directly impacts how well the chromosomal structure is presented for observation.