Students
In general terms, the number of genes directly or indirectly influencing human fertility is currently estimated at around 3000-5000. They can be roughly divided into three groups:
- genes expressed only in the germ line
- genes expressed only or also in the gonads
- genes expressed also during ontogenesis
The last group of genes are the main reason why physicians practising modern methods of artificial fertilisation (ART) are raising critical questions about genetically based infertility defects and the possible risks of transmitting these gene defects of the couple to their progeny inducing then additionally also somatic pathologies which had not been detected in the parents.
The link between genetics and fertility disorders was discovered in 1959, when it was observed that men having the so-called Klinefelter’s Syndrome had one more X chromosome than normal (46,XXY) and women with Turner’s Syndrome had one X chromosome missing (45,X0). To the present day, the molecular causes of the fertility disorders related to these syndromes are unknown. The only thing that is certain is that the sex chromosomes X and Y must include genetic factors crucial to male and female fertility. Consequently, research today focuses mainly on studying the fertility genes on the sex chromosomes X and Y.
