In such cases, defective genes may result in abnormal testes, abnormal sperm production and hormonal malfunction. Infertility is generally irreversible, and sex hormone therapy is necessary to ensure normal sexual function and masculinization in affected men. Men with primary hypogonadism usually have severe, irreversible testicular defects because of genetic abnormalities. Perhaps the best known of the genetic disorders that cause infertility in men. It is found in roughly 1 out of every 500 live births and often is not diagnosed before puberty.
Skeletal abnormalities are more common among men with multiple X chromosomes.
Klinefelter's syndrome typically results in sterility. Although sexual function may be normal, sperm are not produced to father children. Psychological, social and learning problems are common in this group, as is mental retardation. Sex hormone therapy may be very beneficial for prepubescent boys with Klinefelter's syndrome, especially if their blood testosterone levels are low. Specialists generally recommend hormone therapy to ensure optimal sexual development in such cases - including growth of pubic and facial hair, increased size of the penis and scrotum, deepening of the voice, and increased muscular size and strength.