Which condition in males is characterized by the presence of an extra X chromosome?

Klinefelter syndrome is a genetic condition that occurs when a male has an extra X chromosome, resulting in a chromosomal pattern of XXY instead of the typical XY. This additional chromosome can lead to various physical and developmental features, such as reduced testosterone levels, infertility, and some degree of learning difficulties. Males with Klinefelter syndrome may also exhibit symptoms like increased breast tissue development (gynecomastia), decreased muscle mass, and sparse facial or body hair due to the effects of the extra X chromosome on hormone levels and development.

The other conditions listed do not involve the presence of an extra X chromosome in males. Turner syndrome, for instance, is a condition associated with females, where there is a partial or complete absence of one X chromosome. Androgen insensitivity syndrome involves a resistance to male hormones (androgens), leading to the development of female physical traits despite a male (XY) chromosomal configuration. Cryptorchidism refers to the absence of one or both testes from the scrotum, and while it can impact male reproductive health, it is not related to chromosomal abnormalities like Klinefelter syndrome.