Endocrine Abstracts

17 β-Hydroxysteroid Dehydrogenase Type 3 (17β-HSD3) deficiency is an autosomal recessive condition causing 46, XY disorder of sexual development (DSD). The enzyme is responsible for converting of Δ4-Androstenedione (A) to testosterone (T) in testicles. Affected individuals may present with abnormalities of the external genitalia at birth or during childhood and teenage years with virilisation or primary amenorrhea. The aim of this case series is to review the clinical, biochemical and genetics characteristics of individuals diagnosed with 17β-HSD3 deficiency in a single tertiary centre. 4 cases were identified between 2010 and 2023 All had karyotype 46, XY. One presented at birth with palpable gonads, one at age 8 with clitoromegaly and two at age 16 with primary amenorrhea. A summary of the characteristics is presented below: All patients received multidisciplinary input from paediatric endocrinology, genetics, psychology and surgery. Apart from the one diagnosed in infancy all continued to live as females and commenced GnRH analogues and oestrogen. Three of the children had minimal increase in the testosterone following HCG injection with T/A ratio of less than 0.3. 17BHSD is a rare condition that may present in several different ways. The complexity of the condition requires extensive discussion with patients/family and MDT approach for management.