Dr. Ira Shah
M.D, DNB, DCH(Gold Medalist), FCPS

A 6-month-old male child born of non-consanguineous marriage presented with fever and loose motions since 5 days. Stool examination showed presence of pus cells. He had no evidence of dehydration and responded to oral antibiotics. He had a significant past history. He was admitted with LRTI at the age of 3 months and again at the age for 4 months for which he was treated with IV antibiotics. He was also admitted with loose motions at 5 months of age for which he was treated with IV antibiotics. He had no failure to thrive, lymphadenopathy or organomegaly.

In view of the repeated GI and respiratory infections, immunodeficiency such as IgA deficiency was considered. His serum immunoglobulins showed low Serum IgA = <20 mg/dl (Normal = 40-60 mg/dl), Serum IgG = 1283 mg/dl (Normal = 840 –1400 mg/dl) and Serum IgM = 68 mg/dl (Normal = 30-120 mg/dl). He was advised repeat Serum IgA levels every 6 months till the age of 4 years to check if the IgA levels come to normal and confirm the diagnosis of IgA deficiency.

Antibody deficiencies are the most commonly reported immunodeficiencies worldwide (1,2). IgA deficiency is the commonest immunodeficiency described (3). IgA is the only immunoglobulin that is secreted in the body secretions namely the G1 tract and respiratory tract in response to luminal antigens. Serum IgA is transported into the epithelial barriers where it binds to a glycoprotein (secretory component) to form secretory IgA. Secretory IgA prevents the penetration of foreign antigens from the gut, respiratory and other mucosa (4). Thus isolated deficiency of secretory IgA with normal serum IgA is rare (5).

Selective IgA deficient patients have serum IgA level of < 7mg/dl but normal S.IgG and IgM levels. In 50% of patients IgE deficiency is also present (5). This deficiency can be diagnosed reliably only after 4 years of age. Patients with no IgA detected are at higher risk for Anti IgA antibodies on exposure to blood products containing IgA. Patients with IgA deficiency have increased risk for upper respiratory tract infection, allergies, celiac like enteropathies and autoimmune disorders. However many patients are asymptomatic (5). The clinical manifestation in a given patient tends to remain constant (e.g. in patients with autoimmune conditions, recurrent infections do not tend to develop). Patients with recurrent sinopulmonary infections may have other associated antibody abnormality including IgG2 subclass or specific antibody deficiency.