Question

A centromeric probe is used to visualize chromosome 21. Three fluorescent signals are observed in the cell nuclei when stained with this probe. These results would be interpreted as consistent with?

Answer 1

The presence of three fluorescent signals from a centromeric probe on chromosome 21 implies the existence of an extra chromosome, indicating Trisomy 21 or Down syndrome.

Step-by-step explanation:

When a centromeric probe is used to visualize chromosome 21 and three fluorescent signals are observed, these results suggest the presence of an extra copy of chromosome 21, which is consistent with Trisomy 21, also known as Down syndrome. Typically, each chromosome should have two fluorescent signals, one for each chromatid of the homologous pair. However, observing three signals indicates that three chromatids are present, pointing to an additional chromosome.