α2 isotype deficiency

Most patients are healthy. Some patients develop symptoms later in life. Recurrent or chronic upper and lower respiratory tract infections leading to bronchiectasis or cor pulmonale are not common. G. lamblia infection of the gastrointestinal tract is common. Other gastrointestinal diseases, such as spruelike syndrome, ulcerative colitis, and Crohn disease may occur. Autoimmune and collagen vascular diseases such as rheumatoid arthritis, systemic lupus erythematosus without renal disease, autoimmune hepatitis, hemolytic anemia, and endocrinopathies have been described. Patients with undetectable IgA antibodies may develop anti-IgA antibodies of the IgE isotype after receiving blood products. Once sensitized, these patients are at risk for anaphylactic reactions if they receive blood products containing even small amounts of IgA antibodies. Increased excretion of monomeric IgM in the secretions of certain patients may compensate for the lack of IgA, rendering patients less vulnerable to mucosal infections. The association of an IgG subclass deficiency, such as IgG2/IgG4 or IgG3, may worsen the situation.