Swyer syndrome: a genetic condition that affects sexual development. People with Swyer syndrome have a 46X,Y genotype (found in normal males), but develop external and internal characteristics of females. People with the Swyer syndrome have normal female external genital organs along with a uterus with Fallopian tubes. However, in people with the syndrome, the ovaries form abnormally, and are referred to as streak gonads.
People with Swyer syndrome usually have a female gender identity and are typically raised as girls. Because they do not have functional ovaries, hormone replacement therapy during adolescence is used to induce menstruation and development of female secondary sex characteristics, including breast enlargement and uterine growth. Usually, a person with Swyer syndrome will undergo surgery to remove undeveloped ovarian tissue because it is a risk to develop into cancer later in life. Also known as 46,XY complete gonadal dysgenesis.