Differences of Sex Development: A Study of 420 Patients from a Single Tertiary Pediatric Endocrinology Center

Background: Differences of sex development (DSD) are a group of congenital conditions characterized by atypical development of genital structures. The diagnosis is complex and involves clinical, hormonal, and genetic evaluations. Objective: To describe the clinical profile, diagnosis, and management of patients with DSD, with particular attention to genetic diagnosis. Study design: Retrospective study from a tertiary care pediatric hospital in Italy. Methods: 420 patients with DSD referred to the Endocrine Unit of Bambino Gesù Children's Hospital in Rome, Italy, between 2016 and 2023 were included. Results: 75 patients had a 46,XY karyotype, 135 had a 46,XX karyotype, and 210 had chromosomal mosaicism. In our group of pediatric DSD patients, 21/420 patients were born from pregnancies induced with assisted reproduction techniques (ICSI/FIVET). Of these 21 patients, 5 had sex chromosome mosaicism. Using next-generation sequencing (NGS), we identified three new genetic variants: one in the AR gene, one in the NR5A1 gene, and one in the SRY gene. The use of NGS significantly improved the diagnostic yield, and a definitive diagnosis was reached in 84.76% of the entire cohort. Conclusions: This study highlights the challenges in the management of patients with DSD from early recognition to treatment and follow-up. A multidisciplinary approach is essential for a comprehensive evaluation of these conditions and to understand the role and clinical significance of the genetic variants.