This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immune system, Subject name: Medicine
All are true about Bloom syndrome except 
Select and explain. 
A. Decreased levels of Igg, B. (downward arrow) IgM, C. Ig A absent, D. Raised IgE leveis
A: Decreased levels of Igg
Answer: A: Decreased levels of Igg 
Explanation: Bloom's syndrome malignancies-Leukaemia, tongue, oesophageal, colonic, Wilms'tumourAR BLM gene Ref Davidson 23rd edition pg 587