[Analysis of clinical features and genetic variant in a child with Cowden syndrome 1].

Objective: To explore the genetic etiology of a child with Cowden syndrome 1 (CS1).
Methods: A child who had visited the Ningbo Women and Children's Hospital on August 26, 2022 was selected as the study subject. Clinical information of the child was collected. Genomic DNA was extracted from peripheral blood samples of the child and his family members and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing.
Results: The child, a 13-year-old boy, had manifested with severe mental retardation, hyperactivity, autistic behavior, sparse and prominent teeth, macrocephaly, and skin freckles on the penis. His mother had presented with multiple papules, hamartomatous polyps, thyroid adenoma and macrocephaly. WES results revealed that the child has harbored a nonsense c.781C>T (p.Q261*) variant of the PTEN gene, which was inherited from his mother. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.781C>T variant was classified as likely pathogenic (PVS1+PM2_Supporting).
Conclusion: The c.781C>T variant of the PTEN gene probably underlay the pathogenesis in the child and his mother. Above finding has facilitated genetic counseling for this family.