Klinefelter syndrome is caused by an abnormal number of which chromosomes?

Klinefelter syndrome is a genetic condition that occurs due to the presence of an extra sex chromosome in males. Specifically, individuals with Klinefelter syndrome typically have an additional X chromosome, resulting in a total of 47 chromosomes arranged as XXY. This extra chromosome can lead to various physical and cognitive traits associated with the syndrome, such as reduced testosterone levels, enlarged breasts, and reduced fertility.

The presence of three sex chromosomes (XXY) is crucial in defining Klinefelter syndrome, as the typical male chromosomal pattern is XY. This deviation from the norm contributes to the distinct characteristics observed in individuals with the syndrome. Understanding this chromosomal abnormality helps in diagnosing Klinefelter syndrome and addressing the associated medical and social concerns effectively.