What is the genetic cause of Turner's syndrome?

Turner's syndrome is primarily caused by the complete or partial absence of one of the X chromosomes in females, leading to a karyotype of 45, X instead of the typical 46, XX. This chromosomal abnormality results in a range of developmental and physical features, including short stature, lack of ovarian development, and specific physical traits such as a webbed neck and a low hairline.

The absence of one complete X chromosome (or significant structural abnormalities of an X chromosome) is what characterizes the condition, which directly relates to the fundamental issue of aneuploidy affecting sexual development. This genetic alteration disrupts the normal functioning of genes located on the X chromosome, which are crucial for various processes – including growth and development in females.

Understanding this mechanism is essential, as it highlights the significance of the X chromosome in female biology and why its absence results in the clinical presentation of Turner's syndrome. Other choices involve abnormalities that do not pertain to the key genetic issue of Turner's syndrome, which revolves around X chromosome deficiency.