Which of the following is true of Kleinefelter’s syndrome-
**Core Concept**
Kleinefelter's syndrome is a genetic disorder characterized by an extra X chromosome in males, leading to phenotypic features and reproductive issues. The condition is associated with aneuploidy, where there is an abnormal number of chromosomes in the cells, specifically 47,XXY.
**Why the Correct Answer is Right**
Kleinefelter's syndrome is caused by the presence of an extra X chromosome in males, leading to a karyotype of 47,XXY. This results in an imbalance of sex chromosome genes, affecting the development and function of the testes, leading to hypogonadism and infertility. The condition is often associated with tall stature, gynecomastia, and learning difficulties.
**Why Each Wrong Option is Incorrect**
**Option A:** While some individuals with Kleinefelter's syndrome may experience learning difficulties, the condition is not primarily characterized by intellectual disability.
**Option B:** Mosaicism can occur in Kleinefelter's syndrome, but it is not a defining feature of the condition.
**Option C:** Turner syndrome is a separate genetic disorder characterized by the absence of one X chromosome in females (45,X), not the presence of an extra X chromosome.
**Clinical Pearl / High-Yield Fact**
Kleinefelter's syndrome is often associated with an increased risk of autoimmune disorders, such as Hashimoto's thyroiditis and systemic lupus erythematosus.
**Correct Answer:** C.