OR27-01 Combining Clinical and Genetic Approaches in Diagnosing a Large Brazilian Cohort of Patients with 46,XY Differences/Disorders of Sex Development (DSD)

Background: It is recommended a multidisciplinary approach consisted of clinical, hormonal and genetic workups for diagnosing 46,XY DSD. However, no previous study has quantified how useful is this combined approach. Objectives: To retrospectively review the clinical and genetic findings for diagnosing a large cohort of patients with 46,XY DSD from a single Brazilian center. Methods: 247 non-syndromic 46,XY DSD individuals (159 sporadic and 88 familial cases from 39 families) were studied. Clinical and hormonal data were collected from medical files. Testosterone (T), androstenedione (A) were measured by immunoradiometric or immunofluorimetric assays and dihydrotestosterone (DHT) by RIA after celite chromatography or by liquid chromatography tandem mass spectrometry; T/DHT and T/A ratios were calculated. Analysis of sensitivity (SE), specificity (SP) of T/DHT was performed, being the molecular diagnosis considered the gold standard for diagnosing SRD5A2 deficiency. A T/A>0.8 was considered indicative of 17ß-HSDB3 deficiency. The patients were clinically classified into four subgroups: 1) androgen insensitivity syndrome (AIS), 2) gonadal dysgenesis (GD); 3) defects in androgen synthesis (DAS) and 4) DSD of unknown etiology. Molecular studies were performed by Sanger sequencing and/ or massively parallel sequencing (MPS). Results: The median age at first visit was 14 years (range 0.1 to 59 years). The molecular diagnosis was established in 96.5% of the cases with AIS (n=28/29), in 96% of the subjects with DAS (n=46/48), in 36% of the patients with GD (n=21/57) and in 26.7% (n=15/56) with DSD of unknown etiology. The best cut-off for T/DHT in basal state and hCG stimulated was 12.5 (SE=100%; SP=78.57%) and 24 (SE=87.5%; SP=95.7%) respectively. A T/A