Q. What is Galactosemia?
Galactosemia is a genetic disorder caused by deficient functioning of any of these three enzymes namely galactokinase, galactose -1 - phosphate uridyl transferase, or UDP galactose - 4- epimerase. Galactose derived from the hydrolysis of lactose in the intestine is absorbed normally. Bur in the absence of gal-1-P-transferase it leads to the accumulation of galactose, galactose-1-phosphate, and galactitol in the blood and tissues. Accumulation of gal-1-P reduces the intracellular phosphate for high energy phosphate bonds. Thus ATP, GTP and CTP are reduced.
Patients with galactokinase deficiency suffer only from cataract; Galactitol accumulates in the lens of the eye creating an osmotic gradient that allows the glutathione from the lens to efflux. Due to this the concentration of glutathione in the lens is decreased. Glutathione peroxidase and hydrogen peroxidase are inactivated. As a result hydrogen peroxide accumulates in the lens denaturing the proteins of the lens. This leads to the production of lenticular cataracts.