Diagnostic approach to primary immunodeficiency disorders.

Primary immunodeficiency disorders (PIDs) are a heterogeneous group of inherited disorders that affect different components of the immune system. There are more than 150 different disorders which have been described till date. Despite major advances in the molecular characterization of PIDs over the last 20 years, many patients remain undiagnosed or are diagnosed too late with severe consequences. Recognizing different clinical manifestations of PID is the first most important step. It should be followed by use of appropriate diagnostic tools from a vast number of investigations available. This review will focus on important presenting features of PID and laboratory approach for diagnosis of suspected cases of PID.