Klinefelter syndrome
MONDO:0006823A sex chromosome disorder caused by the presence of an extra X chromosome in the male karyotype. Affected individuals are infertile and have a small penis and testes. They tend to have tall stature and long legs and may have difficulties with speech and language development. Gynecomastia may be present.
Also known as: 47,XXY syndrome, Klinefelter syndrome, Klinefelter's syndrome, Klinefelter's syndrome, XXY, XXY syndrome, XXY syndrome (Klinefelter syndrome), hypogonadotropic hypogonadism
14 clinical trials for this condition and its sub-types.
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Age matters: study hopes to boost fertility in klinefelter syndrome
Disease control CompletedThis study looked at 141 men with Klinefelter syndrome (47,XXY) to see if younger men (ages 15–22) have a better chance of finding sperm through testicular biopsy compared to older men (ages 23–55). Participants provided two semen samples, and if no sperm were found, they underwe…
Phase: NA • Sponsor: Hospices Civils de Lyon • Aim: Disease control
Last updated Jun 27, 2026 08:05 UTC
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Scientists dig into the mysteries of x and y chromosomes
Knowledge-focused CompletedThis study looked at 112 people with known differences in their sex chromosomes (X and Y) to better understand how these variations affect health, especially infertility. Participants underwent physical exams, blood and urine tests, imaging, and sensory checks over about 5 days. …
Sponsor: National Human Genome Research Institute (NHGRI) • Aim: Knowledge-focused
Last updated Jun 27, 2026 13:07 UTC