This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
In primary immune deficiency, the following plasma protein fraction can be reduced 
Select and explain. 
A. Alpha1 globulin, B. Alpha2 globulin, C. Beta globulin, D. Gamma globulin
D: Gamma globulin
Answer: D: Gamma globulin 
Explanation: Agammaglobulinemia is a type of primary immunodeficiency of the adaptive immune systemAgammaglobulinemia is characterized by a profound defect in B cell development (<1% of the normal B cell blood count). In most patients, very low residual Ig isotypes can be detected in the serum. In 85% of cases, agammaglobulinemia is caused by a mutation in the BTK gene that is located on the X chromosome.Harrison 19e pg: 2107