This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
A male patient is observed to be HBs Ag antigen positive HBe Ag antigen negative and anti-HBe antibody positive. HBV DNA copies are observed to be 100,000/ml while SGOT and SGPT are elevated to 6 times the upper limit of normal value. What is the likely diagnosis? 
Select and explain. 
A. HBV surface mutant, B. HBV precore mutant, C. Wild HBs Ag, D. Inactive HBV carrier
B: HBV precore mutant
Answer: B: HBV precore mutant 
Explanation: Patient in the question stem is showing features of chronic active hepatitis. HBeAg is negative due to the pre core mutant variant of hepatitis B. Pre core mutation is responsible for the decrease or non production of HBeAg. Such mutations often occur at the time of seroconversion from HBe Ag to anti HBe Ab. Ref: Digestive Involvement in Systemic Autoimmune Diseasesedited by Josep Font, Page 192; Detection of Bacteria, Viruses, Parasites and Fungi: Bioterrorism Prevention By Mariapia Viola Magni, Page 248; Sherlock's Diseases of the Liver and Biliary System edited by James S. DooleypGE 367, 8.