What is the correct modal number for a patient with Turner syndrome with an isochromosome Xq?

Turner syndrome is a genetic condition that affects females and is usually characterized by the presence of a single X chromosome (45,X) instead of the typical two sex chromosomes. Individuals with Turner syndrome can have a variety of chromosomal abnormalities, one of which can be an isochromosome of the long arm of the X chromosome (isochromosome Xq).

In cases of Turner syndrome where there is an isochromosome present, the overall count of chromosomes can still align with the definition of Turner syndrome, meaning they would have a total of 45 chromosomes. However, in this specific scenario of an isochromosome, the count may not accurately reflect the number of fully functional chromosomes. An isochromosome results from the division of a chromosome where one arm is lost, typically leading to two identical arms (one long and one short).

The modal number, which refers to the most frequently occurring number of chromosomes in a normal set of human cells, generally follows the standard of 46 chromosomes (23 pairs), with the typical female karyotype being 46,XX. It's important to note that in certain variations like Turner syndrome, the functional chromosomal structure can result in atypical karyotypes, but the counting method used for