Abstract: Objective: To investigate the oral manifestations, clinical characteristics, and pathogenesis of chronic mucocutaneous candidiasis (CMC) resulting from signal transducer activator of transcription 1 (STAT1) mutation. Methods: Three patients diagnosed with CMC at the Department of Oral Mucosal Diseases, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, between 2018 and 2023 were selected. Their clinical data were meticulously analyzed and summarized in conjunction with a comprehensive literature review. Results: Among three patients, two were male and one was female. The age of onset ranged from 1 to 4 years. All three patients exhibited recurrent candida infection in oral mucosa, while two experienced recurring fungal infections in their skin and toenails. Additionally, one patient had recurrent keratitis and another suffered from respiratory tract infection. The presence of STAT1 gain-of-function mutations was confirmed through genetic testing. These mutations in STAT1 resulted in the developmental defects of helper T cell 17 and impaired the signaling pathway function, which was a significant contributing factor to CMC. Conclusion: Recurrent mucocutaneous candidiasis represents a significant clinical manifestation of CMC. Enhanced gene detection techniques contribute to the early diagnosis, thereby facilitating timely intervention. Furthermore, long-term follow-up is imperative in order to mitigate potential adverse outcomes.

Key words: chronic mucocutaneous candidiasis, signal transducer activator of transcription 1, gain-of-function mutation, pathogenic mechanism