What is the modal number for a diploid karyotype with an additional CBG negative marker chromosome?

The modal number refers to the most frequently occurring number of chromosomes in a given group of cells. In a standard diploid karyotype, the typical chromosome count is 46, comprising 23 pairs of chromosomes.

When considering the contribution of an additional chromosome, like the marker chromosome mentioned, it is crucial to identify its effects. A diploid organism typically has 46 chromosomes.

If an organism has an additional marker chromosome that is not counted in the standard CBG (centromere, chromosome banding) positive system, one might initially consider that this should elevate the total count. However, because the marker chromosome is specifically designated as CBG negative, it does not contribute to the typical diploid count and therefore, the modal number remains influenced primarily by the standard pairs present.

In this scenario, the most frequently observed chromosome number remains at 46, as the standard count does not account for the additional marker chromosome unless it is specifically included in a karyotype readout that recognizes it as a viable chromosome contributing to the count.

Thus, the mode for a diploid karyotype with an additional CBG negative marker chromosome will still be 46, signifying that this is the most common configuration seen in the cells analyzed.