This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
A lady developed severe hyperglycemia in pregnancy and returned to normal after pregnancy with similar history in her mother and sister. What is the Enzyme defect? 
Select and explain. 
A. PFK, B. Glucokinase, C. Enolase, D. Aldolase
B: Glucokinase
Answer: B: Glucokinase 
Explanation: The given description suggests of Maturity onset diabetes of young. MODY is due to mutation in a single gene Inheritance: Autosomal dominant Absence of autoantibodies Absence of ketosis MODY2 Glucokinase gene location: chromosome 7 Glucokinase acts as a sensor for glucose. It has high Km value. In beta cells of pancreas,it acts only when glucose level is high and release the insulin. Due to mutation in glucokinase,insulin is not released even when glucose is high and hyperglycemia is seen Reference: Harpers illustrated biochemistry 30th edition.