(b) : Serum globulins are proteins that include gamma globulins (antibodies) and a variety of enzymes and carrier/ transport proteins. The specific profile of the globulins is determined by protein electrophoresis $(SPEP)$, which separates the proteins according to size and charge. There are four major groups that can be identified : alpha­-$1$ globulins, alpha­-$2$ globulins, beta globulins and gamma globulins. Once the abnormal group has been identified, further studies can determine the specific protein excess or deficit. Since the gamma fraction usually makes up the largest portion of the globulins, therefore antibody deficiency is mainly related with the low level of serum globulins.