Ur Medstudy MCQ 52

The molecule, which is the initiator of cataract formation in the eye lens and whose 1-phosphate derivative is responsible for liver failure,is:
A.Sorbitol
B.Mannitol
C.Inositol
D.Galactitol

The correct answer is: D.Galactitol 

NOTE:

•  Enzyme deficiency in the galactose pathway causes galactosemia.This may be caused by inherited defects in:Galactoskinase,Uridyl transferase,4-epimerase
• The deficiency of uridyl transferase is the commonest enzyme deficiency causing galactosemia
• In galactosemias the serum level of galactose and galactose-1-PO4 is increased due to decrease in their metabolism,caused by deficiency of uridyl-1-transferase
• The increased galactose concentration in the blood and eye is reduced to Galactitol by the enzyme aldolase reductase
• The galacticol cannot escape from the lens cells.Galactitol is a sugar-alcohol and its osmotic effect contributes to injury of lens protein and development of cataract.
• Increased Galactose-1-phosphate in the liver causes depletion of the inorganic phosphate in the liver.This ultimately leads to Liver failure.