Background: Haploinsufficiency of A20 (HA20) is an immune dysregulation disorder caused by loss-of-function TNFAIP3 mutations. This international multicenter study aimed to delineate its clinical spectrum, genetic basis, and natural history.
Methods: A cross-sectional retrospective analysis was conducted in HA20 patients with pathogenic or likely pathogenic TNFAIP3 variants. Clinical, laboratory, and treatment data were assessed. Clustering analysis was applied to evaluate clinical features and disease phenotypes. Patients were stratified by age (<16 years vs ≥16 years), country of origin (China vs United States), and sex.
Results: A total of 185 patients from 41 clinics across 7 countries were included (median age at onset, 3.3 years). Common clinical features were mucocutaneous involvement (80.5%), recurrent fever (63.3%), gastrointestinal symptoms (58.6%), cytopenia (56.6%), arthritis/arthralgia (46.7%), and recurrent infections (35.5%). Compared with adults and patients from the US cohort, intestinal ulcers were significantly more frequent in children and patients from the Chinese cohort (P = .002 and P < .0001, respectively), whereas uveitis was less common in these groups (P = .001 and P < .0001, respectively). Hierarchical clustering of clinical disease phenotypes based on Pearson distance identified two major clusters, an autoinflammation-predominant phenotype and an autoimmune-predominant phenotype. The autoinflammation-predominant phenotype was more common in children and patients from the Chinese cohort (P = .033 and .003, respectively). A total of 89 pathogenic TNFAIP3 mutations were identified, including 46 novel variants. Large deletions were associated with neurologic disease and developmental delay (P = .0054 and .0245, respectively); however, there were no clear associations between disruptions of specific functional A20 domains and age at onset or phenotype. Therapeutically, TNF and IL-1 inhibitors were effective in most patients, with thalidomide and JAK inhibitors provided in refractory cases; 51.5% had obtained minimal disease activity at most recent follow-up.
Conclusions: HA20 is a common dominantly inherited immune dysregulation disorder with phenotypic heterogeneity and potential age-dependent evolution. This large international cohort highlights diagnostic and therapeutic strategies to advance evaluation and management of HA20.
Keywords: Haploinsufficiency of A20; TNFAIP3; autoimmunity; autoinflammation.
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