**Disorders of Sex Chromosomes**
=====================================

**Core Concept**
---------------

Disorders of sex chromosomes refer to genetic conditions where there is an abnormal number or structure of the sex chromosomes, leading to variations in sex characteristics and reproductive development. The most common disorders of sex chromosomes are Turner syndrome (45,X), Klinefelter syndrome (47,XXY), and XYY syndrome (47,XY,Y).

**Why the Correct Answer is Right**
----------------------------------

Turner syndrome is a genetic disorder caused by the presence of only one X chromosome (45,X) in females, resulting in ovarian dysgenesis, short stature, and various physical and developmental abnormalities. This condition is characterized by the absence of one sex chromosome, leading to the characteristic features of Turner syndrome.

**Why Each Wrong Option is Incorrect**
--------------------------------------

* **Option A:** This option is incorrect because it does not specify a disorder of sex chromosomes. Klinefelter syndrome is indeed a disorder of sex chromosomes, but it is not an example of a condition where a chromosome is absent.
* **Option B:** This option is incorrect because it does not describe a disorder of sex chromosomes. XYY syndrome is a condition where an extra Y chromosome is present, but it is not typically associated with the absence of a sex chromosome.
* **Option C:** This option is incorrect because it does not describe a disorder of sex chromosomes. The term "sex chromosome abnormality" is too broad and does not specify a particular condition.

**Clinical Pearl / High-Yield Fact**
-----------------------------------

Turner syndrome is often associated with a characteristic "streaked" appearance of the gonads on ultrasound, which can help in diagnosing the condition.

**Correct Answer: C. Turner syndrome is a genetic disorder caused by the presence of only one X chromosome (45,X) in females.**