[Selective IgA deficiency]. / Le déficit sélectif en IgA.

ABSTRACT

Selective IgA deficiency (SIgAD) is defined by the European Society for Immunodeficiencies (ESID) as a serum IgA of less than 0.07g/L in patients greater than 4 years old with normal levels of IgG and IgM, normal vaccine responses, and with the exclusion of secondary causes of hypogammaglobulinemia. When serum IgA level is higher than 0.07g/L but two standard deviations below normal for age, the condition may be referred to as partial IgA deficiency, which is quite common. SIgAD is the most common primary immunodeficiency in Europe (1/600 in France) and most patients with SIgAD are asymptomatic (75-90%). The clinical complications associated with SIgAD include recurrent respiratory infections (in particular involving Haemophilus influenza and Streptococcus pneumoniae) and gastrointestinal (mainly due to Giardialamblia), autoimmune and allergic manifestations (anaphylaxis if blood products with IgA are administrated), inflammatory gastrointestinal disease. There is no specific treatment for SIgAD and each patient must be managed individually. While asymptomatic subjects do not need any treatment, it is still necessary for them to be up-to-date with vaccinations. If the patient experiences recurrent infections, prophylactic antibiotics may be beneficial. Immunoglobulin replacement therapy should be considered in patients with SIgAD and concomitant IgG subclass deficiency. Treatment for autoimmune and allergic manifestations is based on current standards of care for specific disease entities. To improve quality of life and reduce morbidity, an interdisciplinary team approach is essential.