What is Turner Syndrome caused by?

Turner Syndrome is specifically caused by the loss of part or all of one of the X chromosomes in females. This chromosomal abnormality leads to a variety of developmental and physical characteristics that define the syndrome, such as short stature, delayed puberty, and various health issues.

The condition arises typically in situations where there is a complete absence of one X chromosome (45,X) or in cases involving structural abnormalities of the X chromosome, such as deletions or translocations. The significance of the X chromosome primarily relates to its role in sex determination and development.

Other options, while relating to genetic conditions or developmental issues, do not accurately describe Turner Syndrome. An extra chromosome would imply a condition like Down syndrome, while mutations in a single gene could lead to other genetic disorders, and environmental factors typically do not cause chromosomal aneuploidies like that seen in Turner Syndrome. Thus, the accurate description of the cause of Turner Syndrome is the loss of part or all of an X chromosome.