Hypogammaglobulinemia of infancy

Although transient hypogammaglobulinemia of infancy (THI) has been recognized for many years, little is known about many aspects of this disorder, including the long-term outcome. THI likely represents a heterogeneous group of errors in the immune system presenting with similar clinical and laboratory findings. A major initial step in genotype identification is the careful analysis of the various phenotypes. The authors have identified three different patterns of evolution in Ig concentrations and antibody production in patients presenting with recurrent infections and hypogammaglobulinemia in infancy and early childhood. In group I, Ig and antibody production eventually normalized, but the process may span over a decade and may include a transient phase of IgG subclasses deficiency (only then can they be given the diagnosis of THI). In group II, patients continued to have low IgG levels and poor antibody production (consistent with CVID). In group III, patients' IgG levels normalized, but antibody levels were transient (consistent with dysgammaglobulinemia).