According to the World Health Organization (WHO), about 15% of couples in the world suffer from infertility, and more than 30% of them are caused by genetic abnormalities, and the incidence of Y chromosome microdeletion is about 1/4000 in healthy people, but it is significantly higher in infertile men, with the frequency of microdeletion ranging from 2% to 10% (or even higher). The frequency of Y chromosome microdeletions in Chinese infertile men is 11.5%, which is at a high level. The chromosomes are the genetic objects in the cell, which can be easily stained with alkaline dyes, so they are called chromosomes (chromatin). It is the carrier of genetic material, and is closely related to biological genes. The medical terminology is very high level and unintelligible. Simply put, men and women have 23 pairs of 46 chromosomes, of which 22 pairs are autosomes. The colored bands in the picture above are the carriers of the genetic code, which determine our height and gender; whether we have big eyes and double eyelids or small eyes; whether we are Michael Jordan or Phelps; and even some oncogenes are hidden in these colored bands, which are expressed at some point in life and lead to cancer. …… There is another pair of sex chromosomes, XX for women and XY for men, and today we are going to focus on one of the Y chromosomes, the sex-determining gene that determines male fertility. Men will disappear? The 23rd pair of chromosomes of men are sex chromosomes, as the name suggests, this pair of babies determines whether you are a pure man or not. 22 pairs of autosomes in the 23 pairs of human chromosomes are composed of two chromosomes of about the same size, but the Y chromosome is a dwarf compared to the X chromosome with which it is paired. Now it’s only a third the size of the X! In 2002, Graves and other scientists published an article in Nature stating that the Y chromosome had been shrinking in size during the evolution of early mammals to primates, and predicted that the male chromosome would disappear within 10 million years. One wonders, are men going extinct? So Page and his colleagues began to study the evolutionary history of the Y chromosome. They compared the complete sequences of DNA on the chromosomes of eight mammalian species. They started with earlier species that left the fossil record – including opossums, cows, rats and mice – and worked their way up to more recent species, including rhesus monkeys, chimpanzees and humans. Comparative studies have shown that this Y chromosome “small man evolutionary history” stopped and remained stable 25 million years ago. He proposes that this stability stems from 12 other important genes on the Y chromosome that are unrelated to sex determination, sperm production and male organ development, and that the Y chromosome has an important role in the survival of the whole organism, so the survival of these genes is preferred by evolution. So the question is, if they are stable, why are so many men still unable to have children? Let’s get down to business and learn together what a Y chromosome microdeletion is. The Y chromosome, a small stick, can be divided into a long arm (Yq) and a short arm (Yp), and on the long arm there is a region that determines male spermatogenic function called the AZF region, which is further divided into AZFa, AZFb, AZFc and other regions. These three brothers are important and the consequences of losing them are serious! Y chromosome microdeletion is the second most important genetic factor causing male infertility, second only to Creutzfeldt-Jakob syndrome in terms of incidence. What will happen if these three brothers are lost? AZFa deletion, which occurs at a frequency of 0.5%-4%, is clinically manifested as azoospermia, and the pathological type is support-only cell syndrome. What is the only supporting cell syndrome? It is like growing grapes, the grapevine is set up, but there are no grape seeds ….. The incidence of AZFb deficiency is 1-5%, with clinical manifestations of azoospermia and pathological types of support cell only syndrome or spermatogenic blockage. (To explain what is spermatogenic block, it takes about 74 days for spermatozoa to grow, during which time spermatozoa are transformed from spermatogonia, primary spermatocytes, secondary spermatocytes, spermatocytes and finally spermatozoa, spermatogenic block means that spermatozoa stagnate at a certain stage of the above process and spermatogonia cannot finally become sperm.) AZFbc deletion, with an incidence of 1%-3%, is clinically manifested as azoospermia, with a pathological type of only supporting cell syndrome or spermatogenic block. The karyotype is mostly 46,XX sexual inversion male syndrome (46,XX male) or iso(Y)* double mitotic Y chromosome. In these Y chromosome deletions, testicular sperm retrieval is not recommended due to the absence of sperm production in the testis, and donor insemination is possible. AZFc deletion, with an incidence of about 80%, has diverse clinical manifestations and testicular tissue types, with the main manifestations: azoospermia, severe oligospermia, and progressive decrease in sperm count being the most common. In such men, we recommend early fertility or sperm freezing for preservation. 50% of azoospermia caused by AZFc deficiency can be assisted by second-generation IVF with sperm obtained through testicular puncture. So AZFc deletion is a blessing among misfortunes! Who needs to be tested for Y chromosome microdeletion? Patients with oligospermia (sperm density less than 5 million per ml); male infertility patients with normal sperm density but unknown cause; male infertility with cryptorchidism and varicocele; male infertility patients with unknown cause before medication; wives with unexplained habitual abortion; How to check for Y chromosome microdeletion?1. Take venous blood for testing, no fasting required; 2. 15 working days to issue the report.