Which condition describes males born with an extra X chromosome?

Which condition describes males born with an extra X chromosome?

• A. Klinefelter syndrome
• B. Turner syndrome
• C. Down syndrome
• D. Triple X syndrome

Answer: (A)

Males born with an extra X chromosome have Klinefelter syndrome, typically with the karyotype 47,XXY. The extra X affects male sexual development and can lead to reduced testosterone, infertility, and sometimes learning or language difficulties. This is distinct from Turner syndrome, which occurs in females with a missing X chromosome (45,X); Down syndrome, which is caused by trisomy 21 (three copies of chromosome 21) and is not sex-linked; and Triple X syndrome, which involves females with an extra X (XXX). So the described condition—males with an extra X chromosome—is Klinefelter syndrome.

Males born with an extra X chromosome have Klinefelter syndrome, typically with the karyotype 47,XXY. The extra X affects male sexual development and can lead to reduced testosterone, infertility, and sometimes learning or language difficulties. This is distinct from Turner syndrome, which occurs in females with a missing X chromosome (45,X); Down syndrome, which is caused by trisomy 21 (three copies of chromosome 21) and is not sex-linked; and Triple X syndrome, which involves females with an extra X (XXX). So the described condition—males with an extra X chromosome—is Klinefelter syndrome.