ESPE Abstracts (2015) 84 P-3-787

Identical Twins Raised as Sister and Brother

Rolf Peter Willig


Department of Endocrinology, Hamburg, Germany


Background: Disorders of sex development (DSD) can be caused by many hormonal and genetic defects. One rare condition is a mutation of the SRY-gene disturbing normal sex differentiation. Identical twins with this disorder of varying degree are presented to learn how difficult social sex assignment may be in such a case.

Case presentation: Identical 46, XY twins were born in 1985 from non consanguineous, healthy parents of German origin. The newborns were healthy but showed DSD. Child I presented female external genitalia. Streak gonads with muellerian structures were found by laparotomy. This is the clinical picture of Swyer’s syndrome. Consequently she was raised as a girl receiving estradiol since the age of 12 years. Child II demonstrated a male-like phallus with hypospadia, flat scrotum with two palpable gonads and inguinal hernia. Laparotomy detected two testes with epididymides, a normal vagina, uterus and tubes but no ovarian tissue. All inner structures including dysgenetic testes were resected. This is the clinical picture of oviduct persistence. In consequence he was raised as a boy. At the age of 4 years he was operated for phallus curvature correction. With 5 years of age he got a urethroplasty for hypospadia repair. With 8 years the first artificial testes were inserted. With 13 years testosterone therapy was initiated.

Conclusion: A mutation in SRY-gene is postulated. It disturbed physiologic gonadal development in identical 46, XY twins in different manifestation: In the girl no gonads developed leading to streak gonads and persisting muellerian structures like in Swyer’s syndrome. This twin therefore was raised in a social female sex. In the second twin dysgenetic testes were found with diminished testosterone- and no AMH- production. Accordingly he was born with a vagina and persisting muellerian structures. In respect of his well developed phallus he socially was raised as a boy. Both of the identical twins are very content with their social female and male sex assignment. They live with heterosexual partners, they have a normal vita sexualis, and they wish to have children. They cannot think to have lived up to 30 years in a undefined so called third gender. In their opinion the early gender assignment during infancy was correct.

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