ESPE Abstracts

Introduction: 17 β-Hydroxysteroid Dehydrogenase Type 3 (17β-HSD3) enzyme provides the conversion of ∆4-Androstenedione (A) to testosterone (T) in testicles. 17β-HSD3 deficiency is a rare autosomal recessive cause of 46,XY disorders of sexual development (DSD) and is the most common form of testosterone biosynthesis defects. The external genitalia can vary from normal female appearance to atypical genitalia.

Case Report: A 2-month-old female patient presented with palpable swelling in both groins. There was no consanguinity between the parents of the patient, whose personal and family history was unremarkable. In her physical examination, the external genitalia was female, the phallus was 0.9 cm, the urethral and vaginal openings were separate, and the vaginal entrance was narrow. There were palpable gonads in both inguinal regions. In ultrasonography; there was an appearance compatible with testis in both inguinal canals and a hypoechoic area compatible with the root of the penis in the phallus root. Müllerian structures were not observed. The patient’s karyotype was 46,XY, baseline FSH was 2.4 IU/ml; LH 1.32 IU/ml; ACTH 23 pg/ml; cortisol was 8.44 µg/ml. Basal androgen levels testosterone <0.1 ng/ml; androstenedione 0.3 ng/ml; DHEA-S 1.6 µg/ml; 17-Hydroxyprogesterone 0.22 ng/ml; 11-Deoxycorticosterone was 1.99 ng/ml. Inhibin B level was 187.8 pg/ml (90-400 pg/ml). The basal T/A ratio in mini puberty was <0.8 and the testosterone/dihydrotestosterone ratio in the hCG stimulation test was 10.2 (normal). In genetic analysis, a homozygous mutation of c.239 G>A (P.Arg 80 Gln) in the HSD17β3 gene was detected (mother and father are carriers for that mutation), and it was found to be compatible with 17 β-Hydroxysteroid Dehydrogenase Type 3 Deficiency.

Conclusion: 46,XY DSD due to 17β-HSD3 deficiency may present with inguinal swelling or mild cliteromegaly in infancy and early childhood, and virilization in adolescence. It can often be confused clinically with androgen insensitivity syndrome and 5α reductase type 2 deficiency. Although low T/A ratio supports 17β-HSD3 deficiency, the diagnosis should be confirmed by molecular genetic studies.As a result, this rare disease should be diagnosed in the early period and sex determination should be made, short and long-term treatment plans should be made, patients should be followed in terms of sexual function, fertility, malignancy risk, and appropriate psychiatric counseling should be provided.