ESPE Abstracts

Background: 17β-Hydroxysteroid dehydrogenase type 3 (17β-HSD3) deficiency is a rare cause of 46,XY sex reversal due to a defect in conversion of androstenedione to testosterone. It is autosomal recessively inherited and caused by mutations in 17HSD3.

Objective and hypotheses: To define clinical and laboratory characteristics of 17β-HSD3 deficiency during neonatal period.

Method: An 8-day-old newborn with female external genitalia was admitted to hospital due to bilateral inguinal swelling. She was born to first degree consanguineous parents with a birth weight of 3300 g after an uneventful term pregnancy. Physical examination revealed a weight of 3.48 kg (SDs +0.17), height 47 cm (SDs −0.98), head circumference 35 cm (SDs +0.18), normal vital signs and blood pressure. Genital examination disclosed female phenotype with normal clitoral size, vaginal and urethral openings, and palpable gonads in the inguinal region. Laboratory studies showed normal biochemistry, normal adrenal steroids, low gonadotropin levels, no uterus and ovary in abdomen but testis and epididymis tissue at inguinal area on ultrasound imaging and a 46,XY karyotype. At first month gonadotropin and testosterone levels were still low.

Results: Genetic analyses of 5α-reductase and androgen receptor genes were negative. After hCG stimulation, total testosterone raised to 26.7 ng/dl with a 10-fold increase, normal testosterone:dihydrotestosterone ratio (2), and low testosterone:androstenedione ratio (0.22), leading to the diagnosis of 17β-HSD3 deficiency. Mutation analysis of 17HSD3 gene revealed a novel and possibly pathogenic mutation: c.464A>C.

Conclusion: 17β-HSD3 deficiency should be kept in mind particularly in differential diagnosis of androgen insensitivity syndrome, therefore virilization during adolescence can be avoided. Determination of mutation in 17HSD3 is beneficial for future pregnancies as well.