The latter group includes those with Turner syndrome (i.e., 45,X) and its variants, as well as those with mixed gonadal dysgenesis and a mixture of cell lines, some containing a Y chromosome (e.g., 46,XY/45,X).

The early stages of testicular formation in the second month of gestation requires the action of several genes, one of the earliest and most important of which is SRY: the sex-determining region of the Y chromosome.

Also, the lack of testosterone means that no dihydrotestosterone is formed and consequently the external genitalia fail to virilize, resulting in a normal vulva.

[13] Without AMH, the Müllerian ducts develop into normal internal female organs (uterus, fallopian tubes, cervix, vagina).

[15] As the adrenal glands can make limited amounts of androgens and are not affected by this syndrome, most of these persons will develop pubic hair, though it often remains sparse.

Although an XY karyotype can also indicate a person with complete androgen insensitivity syndrome, the absence of breasts, and the presence of a uterus and pubic hair exclude the possibility.

[19] Swyer syndrome is an example of a condition in which an externally unambiguous female body carries dysgenetic, atypical, or abnormal gonads.

[21] Upon diagnosis, estrogen and progestogen therapy is typically commenced, promoting the development of female characteristics.