Generally speaking, immunodeficiency conditions express a genetic component. In some of these cases, patients may request medical advice due to immune disturbance rather than due to genetic abnormality. Sometimes, the immune defect is not encountered in all cases. Yet, in certain cases, it is realized after diagnosis, while in others the immune defect is not the main clinical problem at all. However, immune defects maybe fatal in some syndromes and require urgent intervention. This review presents a brief overview on the immune response and then delineate the genetic syndromes manifesting immunological abnormalities.