[Clinical features and genetic analysis of a child with STISS syndrome due to variant of PSMD12 gene].

Abstract

Objective: To explore the clinical characteristics and genetic etiology of STISS syndrome (an autosomal dominant disorder characterized by ubiquitin-proteasome system dysfunction) in a child.

Methods: A child with STISS syndrome diagnosed at the Affiliated Women and Children's Hospital of Ningbo University in September 2024 due to "abnormal development of external genitalia" was selected as the study subject. Clinical data were retrospectively collected. Peripheral blood samples were obtained from the child and his family members. Following genomic DNA extraction, whole-exome sequencing (WES) and Sanger sequencing validation were carried out. Pathogenicity of the candidate variants was assessed based on the guidelines from American College of Medical Genetics and Genomics (ACMG). The study was approved by the Ethics Committee of the hospital (Ethics No.: EC2023-094).

Results: The proband, a 16-year-old boy, presented with micropenis, testicular hypoplasia, delayed sexual development, insulin resistance, diabetes mellitus, and obesity. WES revealed that he has harbored a c.934del; p.Met312TrpfsTer3 frameshifting variant of the PSMD12 gene, which was unreported previously. Sanger sequencing confirmed that the variant to be de novo in origin. Based on the guidelines from the ACMG, the variant was classified as pathogenic (PVS1+PM2_supporting+PM6_supporting). The variant was predicted to result in a premature termination codon. Bioinformatics analysis suggested that the amino acid at position 312 is highly conserved, and the variant may therefore affect the protein structure.

Conclusion: Patients with STISS syndrome exhibit clinical features including psychomotor retardation, intellectual disability, distinctive facial features, and urogenital abnormalities. The c.934del (p.Met312TrpfsTer3) frameshift variant of the PSMD12 gene probably underlay the pathogenesis in the proband. Above finding has enriched the mutational spectrum of the PSMD12 gene.