Overview Introduction Monosomy resulting from nondisjuction (XO) mosaicism (XX, XO; XY, XO) only monosomy not aborted in utero no Barr bodies Leads to abnormal sexual differentiation with primary amenorrhea streak gonads menopause before menarche infertility delayed sexual maturation normal intellegence Pathogenesis ↓ estradiol leads to ↑ FSH and LH normal GH and insulin-like growth factor Presentation Physical exam short stature webbed neck shield chest wrist and ankle edema both edema and webbed neck a result of malformed lymphatic vasculature Prognosis, Prevention, and Complications Increased risk for gonadal blastoma (specifically XY, XO mosaics, as Y chromosome increases risk of tumor formation in dysgenic gonads) preductal coarctation of aorta and bicuspid aortic valve dysgerminoma ovarian tumor horseshoe kidney decreased fertility