What is Y chromosome and male infertility?

Along with the development of ICSI in 1993, our center was the first to study the Y chromosome and male infertility, and why tiny amounts of sperm are often found in the testes of azoospermic men previously thought to be making no sperm. You have probably heard a lot about the Y chromosome. It is what determines that a male is a male. We discovered with our first scientific paper on this in 1995 that the Y chromosome contains many genes that are involved in spermatogenesis, and deletions involving these genes are often found in infertile males. There has been a great deal of unknowledgeable discussion about our discovery of these sperm producing genes on the Y and a lot of misinformation. So in this page, I will try to clear up the confusion so you will understand better the genetics of male infertility. Our sequencing the DNA of the Y gives us a deep perspective about infertility genes that are widespread throughout the genome and which are also involved in transmitting infertility to future generations. A benefit of understanding the Y chromosome is it will help us to comprehend why men who are seemingly azoospermic usually have some residual tiny amount of spermatogenesis that can be used for successful ICSI. More importantly, it will expose the futility of trying to increase sperm count with drugs or varicocoele surgery.

Until two decades ago, there were no treatment options for infertile couples when the male had severely impaired spermatogenesis. In fact, there are still no clinical therapies to correct deficient spermatogenesis. Since the introduction of ICSI by us and the Brussels Dutch-Speaking Free University in 1992, however, there has been a revolution in our thinking about male infertility. Infertile couples with the most severe cases of male infertility, even with apparently 100% abnormal morphology and even just rare spermatozoa in the ejaculate, can now have pregnancy and delivery rates not apparently different from conventional IVF with normal sperm.

In 1993, we were the first to introduce microsurgical epididymal sperm aspiration (MESA) in conjunction with ICSI for the treatment of obstructive azoospermia. A few months later, TESE (testicular sperm extraction) was also found to be effective for the majority of cases of non-obstructive azoospermia as well. The reason is that approximately 60% of azoospermic men with presumably no sperm production actually do have a minute amount of sperm production in the testis that is just not quantitatively sufficient to spill over into the ejaculate, but which is adequate for ICSI. Thus, even men with spermatogenesis so deficient in quantity that no sperm at all can reach the ejaculate, could now have children with the use of TESE-ICSI.