This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
The serum concentration of which of the following human IgG subclass is maximum ? 
Select and explain. 
A. IgG 1, B. IgG 2, C. IgG 3, D. IgG 4
A: IgG 1
Answer: A: IgG 1 
Explanation: IgG has four subclasses: IgG1, IgG2, IgG3 and IgG4 due to the presence of gamma1, gamma2, gamma3 or gamma4 H chains. - the subclasses differ from one another in the size of the hinge region and the number and position of the interchain disulfide bonds between the heavy chains. - IgG1 is distributed in human serum in the approximate propoion of 65%, IgG2 in 23%, IgG3 in 8% and IgG4 in 4 %. Reference:Anathanarayan & paniker's 9th edition, pg no: 97 <\p>