Anorchia (or anorchism) is an XY disorder of sex development in which individuals have both testes absent at birth. Within a few weeks of fertilization, the embryo develops rudimentary gonads (testes), which produce hormones responsible for the development of the reproductive system. If the testes fail to develop within eight weeks, the baby will develop female genitalia (see Swyer syndrome). If the testes begin to develop but are lost or cease to function between eight and 10 weeks, the baby will have ambiguous genitalia when it is born. However, if the testes are lost after 14 weeks, the baby will have partial male genitalia with the notable absence of gonads.
Tests include observable lack of testes, low testosterone levels (typical female levels), elevated follicle stimulating hormone and luteinizing hormone levels, XY karyotype, ultrasound or magnetic resonance imaging showing absent gonadal tissue, low bone density, low anti-Müllerian hormone levels, and surgical exploration for evidence of male gonadal tissue.
- Absence of one or both testes
- Lack of secondary sex characteristics
- Puberty failure
In the first several weeks after fertilization, the embryo develops rudimentary sex organs, which are crucial to the development of internal and external genitalia. In the male, if these early testes fail to develop before 8 weeks gestation, the baby will have female genitalia. If the testes are lost between 8 and 10 weeks, ambiguous genitalia will be seen at birth. This means that elements of both male and female internal and external genitalia will be seen. However, if the testes are lost after the critical phase of male differentiation between 12 and 14 weeks, the baby will have normal male internal and external genitalia (penis and scrotum), but the testes will be absent. This is known as congenital anorchia, or the "vanishing testes syndrome". The specific cause is unknown, but in some cases genetic factors are apparent.
Prognosis is good with treatment.
Treatment includes androgen (testosterone) supplementation to artificially initiate puberty, testicular prosthetic implantation, and psychological support. Gender Dysphoria may result in anorchic individuals who are assigned male at birth and raised as male despite lacking the necessary masculinizing hormones during prenatal, childhood, and adolescent development. Anorchic individuals who have a female identity may be administered estrogen alone in place of testosterone as no androgen blockers are necessary due to the lack of gonads.