Diverse clinical manifestations of ARPC1B deficiency- first case series from India

Introduction: ARPC1B deficiency is an immune-related actinopathy manifesting as combined immunodeficiency with or without immune dysregulation. Methods: Clinical and laboratory details of 4 patients with homozygous or compound heterozygous mutations in ARPC1B were analyzed retrospectively. Results: All four patients were symptomatic during infancy. Infection profile included ear infections, pneumonias, abscesses, viral and fungal infections. P2 and P3 had developed cystic bronchiectasis. All four had at least one allergic manifestation such as asthma (3/4), eczema (2/4) and P1 had multiple food allergies. Features of immune dysregulation included Henoch Schonlein Purpura like lesions (2/4), ulcerative colitis (1/4) and pyoderma gangrenosum (1/4). All had neutrophilic leucocytosis during infections. P1, P3 had platelet function defect. All four had lymphopenia affecting one or more T cell subset. All had elevated IgG, IgA and IgE. Conclusion: ARPC1B is a rare IEI with features overlapping with other actinopathies. Early diagnosis is imperative as HSCT can be curative.