[Clinical and genetic analysis of four patients with Phelan-McDermid syndrome due to variants of SHANK gene].

Objective: To explore the clinical phenotype and genetic characteristics of four patients with Phelan-McDermid syndrome (PMS) due to variants of SHANK3 gene.

Methods: Four patients diagnosed with PMS at Guangzhou Women and Children's Medical Center Liuzhou Hospital from January 2020 to January 2025 were selected as the study subjects. Clinical data of the patients were collected. Peripheral venous blood samples were collected from each patient for the extraction of genomic DNA, followed by whole-exome sequencing (WES) and validation by Sanger sequencing. Pathogenicity of candidate variants was rated based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), and multiple bioinformatic tools were used to assess the pathogenic effects of the variants. The study was approved by the Ethics Committee of the Hospital (Ethics No. 2025-007).

Results: All four patients had exhibited language delay and intellectual disability (IQ 35 ~ 65). Some also presented with autism spectrum disorder and schizophrenia, albeit with significant phenotypic heterogeneity. All patients were found to harbor deletions of 22q13.33 region, ranging from 55.46 Kb to 112.64 Kb, primarily involving the SHANK3 gene.

Conclusion: PMS is typically caused by deletions or mutations of the SHANK3 gene. The clinical manifestations are diverse, with developmental delay and intellectual disability being the most common. Accurate diagnosis requires integration of genetic testing and standardized clinical assessment. Genetic screening for suspected patients and at-risk pregnant women is recommended to facilitate their genetic counseling.