Klinefelter syndrome is a genetic condition that affects males who are born with an extra X chromosome. Most males have one X and one Y chromosome, but those with Klinefelter syndrome have at least two X chromosomes and one Y chromosome. This chromosomal difference occurs randomly and affects about 1 in 500 to 1 in 1,000 male births.
The extra X chromosome affects how the body develops, particularly the testicles. This can lead to lower testosterone production and reduced fertility. Many males with Klinefelter syndrome are not diagnosed until adulthood, often when fertility issues arise. Some people with this condition live their entire lives without knowing they have it.
The condition affects each person differently. Some males experience mild symptoms while others have more noticeable physical and developmental differences. Early diagnosis and treatment can help manage symptoms and improve quality of life. Testosterone replacement therapy can address many of the hormonal imbalances associated with this condition.