[Fertility in patients with Klinefelter syndrome (47,XXY)]

In the past 10 years, our knowledge about fertility chances of patients with Klinefelter syndrome (KS, 47,XXY) has changed considerably, especially when regarding the possibility of IVF ICSI treatment (in vitro fertilisation, intracytoplasmic sperm injection) with single testicular spermatozoa. Thus, it is important to take this knowledge into consideration when counselling Klinefelter patients.Germ cell degeneration in the testicles of Klinefelter patients due to their additional X chromosome is an important phenomenon in this disease which is not yet fully understood. When entering puberty, the testicular volume of KS patients increases for a short time with rising testosterone and inhibin B levels at the same time. These decrease, however, and FSH increases during puberty. This seems to indicate a critical point in time when spermatogenetic function of the testicles could still be existent. Thus, in early puberty there could possibly be a time slot when spermatozoa could be detected in the ejaculate or-if not-at least in the testicular tissue. These could be extracted by testicular sperm extraction, cryopreserved and used for intracytoplasmic sperm injection therapy later on. In the literature, a total of 133 births of children from Klinefelter fathers have been reported. This early specific procedure could lead to a better acceptance of their diagnosis and also offer the option of not being incurably infertile.