Klinefelter Syndrome (47,XXY)
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Overview
Plain-Language Overview
Klinefelter Syndrome (47,XXY) is a genetic condition that affects males and involves an extra X chromosome. It primarily impacts the reproductive system, leading to smaller testes and reduced testosterone production. This can cause delayed puberty, infertility, and sometimes breast tissue development called gynecomastia. Many affected individuals may also experience learning difficulties and social challenges. The condition is lifelong and influences physical, hormonal, and sometimes cognitive health.
Clinical Definition
Klinefelter Syndrome (47,XXY) is a chromosomal disorder characterized by the presence of an extra X chromosome in males, resulting in a 47,XXY karyotype. The core pathology involves testicular dysgenesis leading to primary hypogonadism with decreased testosterone production and elevated gonadotropins (LH and FSH). This causes impaired spermatogenesis and infertility. Common clinical features include tall stature, gynecomastia, small firm testes, and variable cognitive impairment. The syndrome results from nondisjunction during meiosis, causing an extra X chromosome. It is the most common cause of male hypogonadism and infertility due to chromosomal abnormalities.