The incidence of Klinefelter Syndrome is 1 in 500 to 650 male births. It is thought that 1 out of 4 Klinefelter Syndrome males have micropenis, but no one knows for sure. However, an adult male’s erect penis that measures (SPL) 3.67 inches (9.32cm) or less is considered by reputable medical orgs to be an “adult” micropenis. This 47,XXY subject’s erect penis is approx 3 inches (7.62cm) as shown. The most common sexual symptoms of XXY are small testes (a/k/a balls) and infertility. Other issues can include impotence, ED, gynecomastia, learning disabilities, and low testosterone. There are many other characteristics and more info can be obtained by searching online.