Men with a 47, XYY karyotype are generally fertile.[12] However, the association between 47, XYY and fertility problems has been reported by several studies with an increased incidence of chromosomally abnormal spermatozoa of men with 47, XXY syndrome.[13],[14] The extra Y chromosome showed an increased risk to deliver to the offspring due to the high prevalence of hyperhaploid sperm.[15] A recent study demonstrated a higher frequency of aneuploid sperm of 37.2-37.8%, with approximately one-half of the abnormalities caused by sex chromosomal aneuploidy.
Despite the XYY karyotype, spermatogenesis in affected men results mainly in 23, X and 23, Y sperm as the supernumerary Y is eliminated during meiosis.