This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Biochemistry
classical type of galactosemia is due to deficiency of ? 
Select and explain. 
A. galactokinase, B. aldose reductase, C. galactose 1-p uridyl transferase, D. galactose dehydrogenase
C: galactose 1-p uridyl transferase
Answer: C: galactose 1-p uridyl transferase 
Explanation: *Galactosemia is due to deficiency of the enzyme galactose 1-phosphate uridyltransferase. *It is a rare congenital disease in infants, inherited as autosomal recessive disorder. * :*Mutation in the GALT gene located on chromosome 9 is responsible for this disorder. 1. Galactose metabolism is impaired leading to increased galactose levels in blood (galactosemia) and urine (galactosuria). 2. Accumulated galactose is diveed for production of galactitol by the enzyme aldol reductase. Galactitol has been implicated in the development of cataract. ref : lipincott 9th ed