Androgen Insensitivity Syndrome(AIS) is a condition caused by a genetic mutation on the androgen receptor gene on people with XY cariotype so they are genetically male but are phenotically female. Baby girls with such mutation have a normal female external genitalia and because of this they are assigned female after they were born.

Complete Androgen Insensitivity Syndrome

They say that it used to be common and some doctors still perform gonadectomy on women with CAIS because they that the condition increase the chances of gonadal cancer in adulthood but I never believed in that and some more recent researchs indicate that the tumor rate is actually pretty low and for other reasons many CAIS women prefer to decline the surgery altogether and keep their internal testes. The testes produce estrogen and along with the testosterone insensitivity this makes tgem more feminine than women without the mutation with XX chromossomes.

Women with CAIS are esterile because they do not have a womb, ovaries and do not have cervix either so they will never get pregnant and do not menstruate and cannot get menopause.

Transgender women were assigned male when they were born but their dysphoria trigger the desire to transition to female. They also have XY chromossomes and are esterile like CAIS women. However a woman with CAIS that got gonadectomy and take estrogen is technically essentially the same as a transgender woman who got bottom surgery.