What is the chromosomal makeup of Klinefelter syndrome?

Klinefelter syndrome is characterized by the presence of an extra X chromosome in males, resulting in a chromosomal makeup of XXY. This condition typically arises due to nondisjunction during meiosis, where chromosomes fail to separate properly, leading to a gamete with an extra chromosome. When this gamete fuses with a normal sperm, the resulting zygote has an abnormal number of sex chromosomes.

Individuals with Klinefelter syndrome often exhibit various physical, developmental, and reproductive challenges, such as reduced testosterone levels, infertility, and some degree of learning difficulties. Understanding the chromosomal makeup—specifically the presence of that extra X chromosome—is critical for diagnosing and managing the condition effectively.

The other options represent distinct chromosomal patterns that are not related to Klinefelter syndrome: two X chromosomes (XX) represent normal female chromosomal composition, XY corresponds to typical male composition without any chromosomal abnormalities, and XXX signifies Turner syndrome, which involves an additional X chromosome in females but is unrelated to Klinefelter syndrome.