Abstract: Objective　To explore the clinical features, biochemical and immunological findings of chronic mucocutaneous candidiasis (CMC) due to gain-of-function mutations in STAT1 in children. Method　The clinical data of CMC in 5 children diagnosed by genetic examination from 2016 to 2019 were retrospectively analyzed. Results　In 5 patients (4 males, 1 female) the mean age at onset was 4.2±3.6 months (1-10 months). The mucosal infection was found in all of 5 cases, recurrent respiratory tract infection in 4 cases, skin infection in 4 cases, repeated candidiasis of fingernails and toenails in 3 cases, Hashimoto's thyroiditis in 2 cases, and hypothyroidism, hypoparathyroidism, hypoadrenocorticism and dwarfism in one case each. The gene mutation sites of the 5 children were all located in STAT1, which were c.849G >T, c.988C >A, c.862A > G, c.1154C >T, and c.974T >A, respectively. IgG and IgE were normal in 5 cases, and IgA and IgM were significantly reduced in 2 cases. One patient had decreased CD3+ cells, 1 patient had decreased CD3+CD4+ cells, and 1 patient had significantly decreased CD19 cells. Decreased CD3+ cells, CD3+CD4+ cells and CD19 cells were found in one case each. There was no abnormality in the blood cell count of the 5 children, There were the significantly increased anti-thyroglobulin antibody and anti-thyroid peroxidase antibody in 2 cases, and the decreased parathyroid hormone in 1 case and decreased cortisol in 1 case. Two cases were positive in G test, but no invasive fungal infection was found. Conclusions　Repeated Candida infection of skin, mucosa and nails is an important clinical manifestation of CMC. Screening of immune function is suggestive, and gene testing is required to confirm the diagnosis.

Key words: chronic mucocutaneous candidiasis;　clinical characteristic;　gene mutation;　child