Pure XX gonadal dysgenesis in identical twins.

Pure gonadal dysgenesis has been described in several sibships. We report a pair of monozygous twins and their younger sister with secondary amenorrhea. They had no associated congenital anomalies. Plasma FSH levels were elevated and the ovarian biopsies showed absence of follicular structures. Their karyotypes were 46XX, further supporting the concept that his form of familial gonadal dysgenesis is an autosomal recessive defect.