Primary immunodeficiencies presenting in adolescence.

Recurrent infections are a common problem in pediatrics. For most children the frequency of infection decreases over time, but recurring, severe, or unusual infections may be a sign of a primary immunodeficiency disease. Primary immunodeficiency diseases are a heterogeneous group of more than 120 disorders thataffect various parts of the immune system, leading to an increased susceptibility to infection. Many primary immunodeficiency diseases are not diagnosed until late childhood or adolescence. This article will review the diagnosis and treatment of those primary immunodeficiencies that are most likely to present with clinical signs and symptoms during adolescence and young adulthood.