Swyer syndrome
(SWY-er SIN-drome)
A rare genetic condition in which people who have an X chromosome and a Y chromosome (the usual pattern for males) look female. They have normal female reproductive organs, including a uterus, fallopian tubes, and vagina. However, the ovaries do not develop and are replaced by clumps of tissue where they would normally form. Swyer syndrome is usually not diagnosed until puberty, when menstrual periods do not begin as they should. Having Swyer syndrome increases the risk of certain types of germ cell tumors.