Azoospermia is that the medical condition of a person whose semen contains no sperm. It is related to infertility, but many forms are amenable to medical treatment. In humans, azoospermia affects about 1% of the male population and maybe seen in up to 20% of male infertility situations in Canada. Pretesticular azoospermia could also be caused by congenital hypopituitarism, Kallmann syndrome, Prader-Willi syndrome, and other genetic conditions that cause GnRH or gonadotropin deficiency. Testicular azoospermia is seen in Klinefelter syndrome(XXY) and therefore the XX male syndrome. In addition, 13% of men with azoospermia have defective spermatogenesis that is linked to defects of the Y chromosome. Such defects tend to be de novo micro-deletions and affect usually the long arm of the chromosome.