The dilemma of the gender assignment in a Portuguese adolescent with disorder of sex development due to 17β-hydroxysteroid-dehydrogenase type 3 enzyme deficiency

Summary The development of male internal and external genitalia in an XY fetus requires a complex interplay of many critical genes, enzymes, and cofactors. The enzyme 17b-hydroxysteroid-dehydrogenase type 3 (17bHSD3) is present almost exclusively in the testicles and converts Delta 4-androstenodione (D4) to testosterone. A deficiency in this enzyme is rare and is a frequently misdiagnosed autosomal recessive cause of 46,XY, disorder of sex development. The case report is of a 15-year-old adolescent, who was raised according to female gender. At puberty, the adolescent had a severe virilization and primary amenorrhea. The physical examination showed a male phenotype with micropenis and blind vagina. The Tanner stage was A3B1P4, nonpalpable gonads. The karyotype revealed 46,XY. The endocrinology study revealed: testosteroneZ2.38 ng/ml, D4O10.00 ng/ml, and low testosterone/D4 ratioZ0.23. Magnetic resonance imaging of the abdominal–pelvic showed the presence of testicles in inguinal canal, seminal vesicle, prostate, micropenis, and absence of uterus and vagina. The genetic study confirmed the mutation p.Glu215Asp on HSD17B3 gene in homozygosity. The dilemma of sex reassignment was seriously considered when the diagnosis was made. During all procedures the patient was accompanied by a child psychiatrist/psychologist. The teenager desired to continue being a female, so gonadectomy was performed. Estrogen therapy and surgical procedure to change external genitalia was carried out. In this case, there was a severe virilization at puberty. It is speculated to be due to a partial activity of 17bHSD3 in the testicles and/or extratesticular ability to convert D 4t o testosterone by 17bHSD5. Prenatal exposure of the brain to androgens has increasingly been put forward as a critical factor in gender identity development, but in this case the social factor was more important for the gender assignment.