Transgender hormone therapy (male-to-female) males is associated with higher serum estrogen. Both estrogen and testosterone help to stimulate bone formation, especially during puberty. Estrogen is the predominant sex hormone that slows bone loss, even in men. In spite of the induction of breast development, transgender women who undergo HRT do not have an increased risk of breast cancer. Only a handful of cases of breast cancer have ever been described in transgender women who have undergone male-to-female HRT. This is in accordance with research in cisgender men in which gynecomastia has been found not to be associated with an increased risk of breast cancer,
XX male syndrome gene on the Y chromosome is moved to become part of an X chromosome. The presence of the translocated SRY gene leads to an XX embryo developing male characteristics. In rare cases, an XX male does not have the SRY gene. The exact cause of this condition is unknown but it has been proposed that mutations in the SOX9 gene may contribute to this syndrome since SOX9 plays a role in testes differentiation during development. Another proposed cause is mutations to the DAX1 gene which encodes a nuclear hormone receptor. DAX1 represses masculinizing genes, therefore, if there is a loss