[2][1] Based on limited evidence, most XX males appear to have typical body and pubic hair, penis size, libido, and erectile function.

[18] Multiple studies in mice have also found largely normal male-type germ cells in XX males soon after birth, but a progressive loss with maturation.

[24] The SRY gene, normally found on the Y chromosome, plays an important role in sex determination by initiating testicular development.

This exchange occurs as a random event during the formation of sperm cells in the affected person's father.

Individuals with SRY-negative 46,XX testicular disorder of sex development are more likely to have ambiguous genitalia than are people with the SRY-positive form.

[3][2] The exact cause of this condition is unknown, but three theories have been proposed: first, undetected gonadal mosaicism for SRY; second, de-repression of male development due to mutations in genes on chromosomes other than the Y chromosome; third, altered expression of other genes downstream of SRY, resulting in masculinisation.

[27] For example, it has been proposed that mutations in the SOX9 gene may contribute to this syndrome, as SOX9 plays a role in testes differentiation during development.

[28][23] Another proposed cause is mutations to the DAX1 gene, which may suppress masculinisation; if there is a loss of function of DAX1, then testes can develop in an XX individual.

[32] Indicators include two testes which have not descended the inguinal canal, although this is seen in a minority of XX males, and the absence of Müllerian tissue.

[2][21] Treatments are generally focused on affirming the gender presentation of affected men, vary to a large degree based on the phenotype of the individual, and may include counselling.

[35] Conversely, the individual may wish to become more feminine and feminizing genitoplasty can be performed to make the ambiguous genitalia appear more female.

[36] There is no treatment for infertility in XX males – supportive management and alternatives such as sperm donation or adoption are recommended.