What is the characteristic karyotype for Turner syndrome?

Turner syndrome is characterized by the presence of a single X chromosome in females, resulting in a total of 45 chromosomes rather than the usual 46. The typical karyotype for Turner syndrome is 45, XO, where "X" represents the one present X chromosome and "O" indicates the absence of a second sex chromosome. This condition leads to various clinical features such as short stature, ovarian dysgenesis, and other physical anomalies.

In contrast, the other karyotypes mentioned do not correspond to Turner syndrome. A karyotype of 46, XX is typical for normal females. A karyotype of 47, XXX is associated with triple X syndrome, which can result in some clinical features but is distinct from Turner syndrome. Finally, a karyotype of 46, XY is found in normal males. Thus, the distinct karyotype of Turner syndrome is accurately represented by 45, XO, which underscores the genetic basis of this condition.