General Medical Information

Secondary Sexual Development

Joe Leigh Simpson

Although streak gonads usually are present in 45,X individuals, about 3% of adult cases menstruate spontaneously and 5% show breast development. Occasionally, the interval between menstrual periods appears normal in 45,X patients, and fertile patients have been reported. Although an undetected 46,XX cell line should always be suspected in menstruating 45,X patients, it is plausible that a few 45,X individuals could be fertile, inasmuch as germ cells are present in 45,X embryos.

The rare offspring of 45,X women probably are not at greatly increased risk for chromosomal abnormalities, although theoretically they should be. Some authors disagree with this statement, and recent work using X-specific fluorescence in situ hybridization probes suggests low-grade 45,X/46, XX mosaicism in some women experiencing repeated abortions. Irrespective, menstruation and fertility occur so rarely that 45,X patients should be counseled to anticipate primary amenorrhea and sterility. After hormone therapy is initiated in such women, uterine size becomes normal. This permits 45,X women to carry pregnancies in their own uterus after receiving donor embryos or donor oocytes and fertilization in vitro with their husband’s sperm.