[Clinical characterization and genetic analysis of two Chinese patients with Cowden syndrome due to variants of PTEN gene].

OBJECTIVE

To explore the clinical features and genetic etiology of two Chinese patients with Cowden syndrome (CS).

METHODS

Two patients diagnosed with multiple gastrointestinal polyps by gastroenteroscopy at Henan Provincial People's Hospital in September and November 2023 were selected as the study subjects. Clinical data of the patients were collected. Whole exome sequence (WES) was carried out. Candidate variants were verified by Sanger sequencing. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2018-03-01).

RESULTS

The patients were diagnosed with multiple gastrointestinal polyps in addition with polypoid changes of the gallbladder. Genetic testing revealed that patient 1 has harbored a heterozygous c.738dupG (p.Leu247Valfs*6) variant of the PTEN gene, which was unreported previously. Patient 2 has harbored a heterozygous c.469G>T (p.Glu157Ter) variant of the PTEN gene, which was known to be pathogenic. None of their family members was found to harbor the above variants. Based on the guidelines from the American College of Medical Genetics and Genomics, both variants were rated as pathogenic (PVS1+PM2_Supporting+PP3+PP4). Bioinformatic analysis suggested that both variants can significantly affect the tertiary structure of the PTEN protein.

CONCLUSION

The heterozygous variants of the PTEN gene probably underlay the CS in both patients. Discovery of the novel variant has enriched the mutational spectrum of the PTEN gene.