Supplementary Material for: Molecular Diagnosis of 46,XY Disorders of Sex Development: An Efficient Initial Molecular Analysis Using a Custom-Designed Targeted Gene Panel in a Single-Center Study

Background: The management of 46,XY DSD is challenging due to genetic heterogeneity and phenotypic variability. This study aimed to characterize the clinical and genetic findings in patients with 46,XY DSD, using a targeted NGS panel for molecular evaluation. Methods: A targeted DSD gene panel covering 31 genes was applied in 112 patients with nonsyndromic 46, XY DSD. Forty-six patients had previously tested negative for AR and SRD5A2 by Sanger sequencing. Patients were clinically categorized into disorders of gonadal development, androgen synthesis or action. Variant classification was performed according to the ACMG criteria. Results: Among the 38 variants detected, 32 were pathogenic or likely pathogenic. Nineteen variants (50%) were novel. A molecular diagnosis was established in 31 patients (27.7%) and inclusion of previously diagnosed cases would have increased the overall diagnostic yield to 43.8%. The HSD17B3 variants were the most common, followed by NR5A1and LHCGR. In eight patients, the genetic findings led to reclassification of their clinical diagnosis, particularly in those initially suspected to have a disorder of androgen action. Conclusion: NGS is a valuable diagnostic tool in the evaluation of 46,XY DSD, offering improved diagnostic yield. For patients without molecular diagnosis, more comprehensive genomic analyses, including non-coding regions, are required.