Distribution of primary immunodeficiency diseases diagnosed in a pediatrictertiary hospital

Background: Advances in immunologic techniques in recent years have led to increased recognition of primary immunodeficiency disorders, with IgA defic iency the most common phenotype reported by most registries. There have als o been reports of increased associated incidence of autoimmunity, allergy, and other diseases. Objectives: We wished to determine the percentage of different primary immu nodeficiency disorders seen in a pediatric tertiary hospital and to determi ne the association of primary immunodeficiency disorders with other disease s that are not part of classic immunodeficiency disorders. Methods: We performed a retrospective review of the patients referred to ou r allergy/immunology clinic for immunologic evaluation of recurrent infecti ons during an 8-year period. We also reviewed pathology reports with postmo rtem diagnosis of immunodeficiencies not identified while patients were ali ve. Results: Of the 91 patients with primary immunodeficiency disorders evaluat ed, the majority had predominantly antibody deficiencies (67%). The most co mmon phenotype was specific antibody deficiency with normal immunoglobulins (23.1%), defined as inability to mount an adequate response to pneumococca l polysaccharides followed by IgG2 subclass deficiency (17.6%). These two p henotypes were diagnosed mostly in the last 2 years of the survey. Associat ed diseases, found in 40% of patients, were mostly allergic conditions foll owed by syndromic/chromosomal disorders. Conclusion: The study reveals that specific antibody deficiency with normal immunoglobulins followed by IgG2 subclass deficiency was the most frequent ly diagnosed primary immunodeficiency disorder in our patient population. I t also indicates that immunodeficiency disorders should be considered in pa tients with other abnormalities like allergic and syndromic/chromosomal dis orders that present with recurrent infections.