Klinefelter Syndrome (47,XXY or XXY syndrome) occurs when an individual has at least two X chromosomes and at least one Y chromosome. It typically results in small testes and reduced fertility.

Genetic Information from: NIH, National Library of Medicine, Genetics Home Reference https://ghr.nlm.nih.gov/condition

https://ghr.nlm.nih.gov/condition/klinefelter-syndrome

• Klinefelter’s syndrome, see Klinefelter syndrome