Clinical Characteristics and Treatment of Blau Syndrome in Chinese Children-a National Multicenter Study

Objective To study the demographic and clinical characteristics, correlation of genotype and phenotype and treatment of Blau syndrome to facilitate early diagnosis and timely treatment of Blau syndrome. Methods Seventy-two patients with Blau syndrome from 11 centers from May 2006 to April 2022 were retrospectively analyzed, and their general information, clinical data, laboratory examination and treatment medication were collected. Results The distribution of patients with Blau syndrome was uniform in geographical north and south of China, and there was no obvious gender bias. The mean age of onset was (14.30±12.81) months, and the age of diagnosis was (55.18±36.22) months. 35% of patients with Blau syndrome happened before 1 year old, and all patients developed before 5 years old. 87.50% (63/72) had granulomatous arthritis, 65.28% (47/72) had rash, 36.11% (26/72) had ocular involvement, 27.78% (20/72) had fever, and 15.28% (11/72) had pulmonary involvement. Arthritic manifestations of Blau syndrome were most at risk, followed by rash, ocular involvement, and fever.The first 25 months of the disease, the risk of developing a rash was the greatest. The risk of developing arthritis was the greatest between 25 months and 84 months. The main mutations were p.R334Q and p.R334W, and patients with p.R334Q mutation had relatively high incidence of fever (35.71%[5/14] vs. 14.29%[1/7], P=0.43) and ocular involvement (42.86%[6/14]vs. 28.57%[2/7], P=0.51). There was a relatively high incidence of rash (85.71%[6/7] vs. 64.29%[9/14], P=0.59) in patients with the p.R334W mutation. Forty-five patients(62.50%)were treated with a combina-tion of glucocorticoid and methotrexate. Twenty-two patients were treated with tumor necrosis factor antagonist in addition to glucocorticoid and methotrexate. Conclusions The risk of different clinical manifestations of Blau syndrome from high to low was arthritis, followed by rash, ocular involvement and fever. The main treatment was glucocorticoid combined with methotrexate, to which biological agents could be added.