Zhang is the backbone of the company, due to excellent work performance, at the age of 35 became vice president. Preparing to have a child this year, he went to the hospital and was diagnosed with azoospermia. The results of the in-depth etiological analysis also came out last week, and Xiao Zhang’s Y chromosome microdeletion test report showed an AZFa deletion. What exactly is this problem? What is the connection between azoospermia and the Y chromosome? Zhang’s primary care physician explained this: We know that chromosomes are the carriers of genes. There are 23 pairs of chromosomes in human cells, including 22 pairs of autosomes and one pair of sex chromosomes. The sex chromosomes include the X and Y chromosomes, which determine the sex of the human being. The Y chromosome is lazy and small compared to the X chromosome, not only is it one-third the size of the X chromosome, but most of its DNA sequences are non-functional and the genes involved in “work” are not even one-tenth the size of the X chromosome. Studies of genes on the Y chromosome have revealed that there are genes associated with spermatogenesis in the q11 region of the long arm of the Y chromosome, and that small deletions of segments in this region (i.e., Y chromosome microdeletions) can cause spermatogenic dysfunction, resulting in azoospermia or oligospermia, leading to male infertility, and these segments are called azoospermia factors (AZF). It is relatively certain that there are three loci on the AZF gene that are not connected to each other and are related to spermatogenesis, denoted by AZFa, AZFb, and AZFc, respectively. (1) AZFa deletion often manifests as spermatogenic dysfunction or support cell only syndrome; (2) AZFb deletion manifests as impaired sperm maturation, remaining at the spermatocyte level and unable to continue maturation and differentiation; (3) AZFc deletion has diverse manifestations, which may include normal spermatogenic function, azoospermia, severe oligospermia, and spermatozoa, AZFc deletions are more common than AZFa and AZFb deletions, and there are also special types of AZFa and AZFb deletions. Knowing the result of Y chromosome microdeletion, Zhang could not understand how he could be in such a situation. In fact, Y chromosome microdeletions are not usually caused by heredity, because patients with AZFa and AZFb deletions are often unable to obtain offspring, mainly due to genetic mutations that occur during the development of the patient. However, the advent of assisted reproductive technology has allowed many patients with AZFc deletion with severe oligozoospermia to obtain offspring of their own. If the offspring are boys, they inherit the AZFc deletion, while girls do not have such a problem. Therefore, it is essential to complete a karyotype analysis and testing for Y chromosome microdeletions before proceeding with assisted reproduction. Finally, Xiao Zhang asked her doctor if there was any solution to her problem, but he also said there was nothing more he could do. If the AZFa or AZFb deletion is detected, no further testing and treatment is needed at this stage of medical technology, and the only options are adoption or artificial insemination by donor sperm. Some azoospermia patients with AZFc deficiency have found sperm through medication or testicular biopsy. If the patient is severely oligospermic and AZFc deletion is found, the condition of severe oligospermia may be associated with Y chromosome microdeletion. After ruling out other factors affecting semen quality, assisted reproduction techniques may be considered, preferably with preimplantation genetic diagnosis (PGD), to avoid the problem of inheriting AZFc deletion in the offspring for boys.