Q-115. A newborn infant refuses breast milk since the 2nd day of birth, vomits on force-feeding but accepts glucose-water, develops diarrhea on the third day, by 5th day she is jaundiced with liver enlargement and eyes show signs of cataract. Urinary reducing sugar was positive but blood glucose estimated by glucose oxidation method was found low. The most likely cause is deficiency of:
a) Galactose-1-phosphate uridyl transferase
b) Beta galactosidase
c) Glucose-6-phosphatase
d) Galactokinase
Answer: Galactose-1-phosphate uridyl transferase
Explanation:
Galactose 1 phosphate uridyl-transferase is missing in individuals with classical Galactosemia.
Galactose 1 phosphate and therefore Galactose accumulate in cells.
Accumulated Galactose is shunted into side-pathways such as that of Galactitol production.
This reaction is catalyzed by aldose reductase, same enzyme that converts glucose to sorbitol.
More benign form of Galactosemia is caused by a deficiency of galactokinase.
Classical Galactosemia:
Uridyl-transferase deficiency
Autosomal recessive disorder
It causes Galactosemia and galactosuria, vomiting, diarrhoea and jaundice.
Accumulation of Galactose 1 phosphate and Galactitol in nerve, lens, liver and kidney tissue causes liver damage, severe mental retardation and cataracts.
Antenatal diagnosis is possible by chorionic villus sampling.
Therapy: Rapid removal Galactose i.e. lactose from the diet.