The management of patients with a selective IgA deficiency currently consists of symptomatic treatment with treatment of infections by occasional or prolonged antibiotic therapy, immunosuppressive treatments for autoimmune pathologies, symptomatic treatment of allergic manifestations.

IVIG supplements are sometimes proposed in the event of recurrent infections and the demonstration of deficiencies in IgG subclasses (IgG1, 2, 3) often not sought for diagnosis The factors associated with the severity of clinical manifestations are not well identified and patients with IgA deficiency must be monitored over the long term because of the risk of the appearance of autoimmune manifestations and neoplasia. The identification of such factors could lead to the proposal of close monitoring for these patients.

IgA deficiency, which is frequent, has not been identified as a risk factor for severe COVID-19 infection, probably due to a lack of studies with sufficient recruitment. The therapeutic attitude concerning patients with an IgA deficiency in the event of COVID-19 infection is therefore not consensual.

There is currently no action to be taken regarding the risk of transmission of IgA deficiency.

Inclusion criteria:

• Major subject (≥18 years old)
• Subject treated at the HUS, with a primary selective IgA deficiency, considered as definitive (IgA concentration < 0.07g/L or total absence of IgA on immunofixation) or as probable (IgA concentration lower than two standard leads to standard for age) with no other humoral immunodeficiency and no other cause of decreased gammaglobulins 01/01/2005 to 01/31/2022.
• Subject having not expressed, after being informed, their opposition to the reuse of their data for the purposes of this research.

Exclusion criteria:

. Subject who expressed their opposition to participating in the study

Major subject (≥18 years old) with a primary selective IgA deficiency treated at the HUS from 01/01/2005 to 01/31/2022