Klinefelter syndrome is caused by the presence of which chromosomal arrangement?

Klinefelter syndrome is indeed characterized by the presence of an extra X chromosome in males, leading to a chromosomal arrangement of XXY. This condition arises from nondisjunction during meiosis, where the chromosomes fail to separate properly, resulting in a sperm or egg with an extra X chromosome. When this gamete unites with a normal gamete from the other parent, the resulting zygote has three sex chromosomes instead of the typical two, which leads to the phenotype seen in Klinefelter syndrome.

Individuals with Klinefelter syndrome are often noted for features such as testicular dysgenesis, gynecomastia, and infertility, among other physical and developmental traits. The presence of the additional X chromosome disrupts normal male sexual development and function, leading to the various clinical manifestations associated with the syndrome. Understanding the chromosomal basis of Klinefelter syndrome helps in diagnosing the condition and managing its effects on health and development.