A 6-month-old male baby comes with vomiting, lethargy and severe jaundice when weaning was staed with fruit juice. Which of the following enzymes is defective?

The above clinical features on the initiation of fruit juice suggests a disorder of fructose metabolism. Hereditary fructose intolerance (HFI) is due to deficiency of the enzyme Aldolase B. Individuals affected with HFI are asymptomatic until they ingest fructose or sucrose (usually in the form of fruit, fruit juice or sweetened cereal). Symptoms include : Hepatomegaly Jaundice Vomiting Lethargy Convulsions Hypoglycemia Urine reducing sugar (Benedict's test) and tests for ketoses (Rapid Furfural and Seliwanoff's test) are positive. Treatment is removal of fructose and sucrose from the diet. Reference: Lippincott's Illustrated biochemisty 6th Edition Pg 138