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
A patient presents with recurrent swelling of the lips as shown. He has no itching. Family history is positive. Which of the following is deficient in this patient? 
Select and explain. 
A. C1,C2,C4, B. C1 inhibitor, C. C3b inactivator, D. C5-C8
B: C1 inhibitor
Answer: B: C1 inhibitor 
Explanation: This boy presents with features of hereditary angioneurotic edema, which is due to deficiency of C1 inhibitor. C1 inhibitor deficiency - Hereditary angioedema. C1, C2, C4 deficiency - Collagen vascular disorders C5-C8 deficiency - Recurrent bacteremia with Neisseria. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition