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FRI0509 Chromosome 22Q11.2 Deletion Syndrome (Digeorge Syndrome) and Autoimmunity: A French Retrospective Pediatric Study of 15 Cases

Background The prevalence of autoimmunity in 22q11.2 deletion syndrome (chr22q11DS) is 8.5%. Objectives However, there is a lack of clinical description in the literature. Methods From a French retrospective study, we have collected the data of autoimmunity in patients with chr22q11DS. For each patient: initial presentation, treatment, outcome, antibodies and lymphocyte subset analyses have been collected. Results Fifteen cases were selected. The age at onset of autoimmunity ranged from 1 to 14 years old (median 4 years), most children had several autoimmune manifestations (median 2). Seven patients had autoimmune cytopenias (7 thrombopenias, 5 anemias, 3 neutropenias) and among them, 2 children also had autoimmune hepatitis. Five juvenile idiopathic arthritis were observed: 3 severe polyarthritis rheumatoid factor negative, 1 spondylarthropathy with uveitis and 1 oligoarthritis. 3 children developed mere joint inflammatory pain associated with good response to NSAIDs. Additionally, one celiac disease was diagnosed associated with B+ polyclonal lymphoproliferative disease. One child had autoimmune thyroiditis. A teenager presented acute focal neurological symptoms with hyperintensities of the brain white matter at MRI and positive anti-nuclear and anti-histones antibodies. A Churg-Strauss syndrome was considered, facing severe asthma, nasal polyps, corticosteroid dependence and fever, but ANCA were negative. All patients received several treatments (median 2) and currently, after a median follow-up of 10 years, 10 patients are in complete remission (5 without any treatment and 5 with immunosuppressants), 3 are in partial remission, 1 pancytopenia and 1 polyarthritis are not controlled. The age at chr22q11DS diagnosis ranged from the neonatal period to 16 years (median 7 years). In 8 cases chr22q11DS was diagnosed after the beginning of autoimmunity with a delay from 1 to 11 years (median 7 years). Lymphocyte subset analyses have shown lymphopenia, with a reduction of naïve T-cell count. Conclusions Chr22q11DS, similar to other primary immunodeficiencies, must be considered facing atypical autoimmunity, even though clinical dysmorphic features are mild. The diagnosis is easily confirmed by fluorescence in situ hybridization study. Naïve T-cell lymphopenia may predispose to a high risk of autoimmunity. Disclosure of Interest None declared