Galactitol

Galactitol (dulcitol) is a sugar alcohol, the reduction product of galactose. In people with galactokinase deficiency, a form of galactosemia, excess dulcitol forms in the lens of the eye leading to cataracts.

Galactitol is produced from galactose in a reaction catalyzed by aldose reductase. Galactose itself comes from the metabolism of the disaccharide lactose into glucose and galactose.

The other common galactose metabolism defect is a defect in galactose-1-phosphate uridylyltransferase, an autosomal recessive disorder, which also causes a buildup of galactitol as a result of increased concentrations of galactose-1-phosphate and galactose. The toxicity associated with galactose-1-phosphate uridylyltransferase deficiency is associated with symptoms of hepatosplenomegaly and mental retardation in addition to the cataracts caused by galactitol buildup.

Other articles related to "galactitol":

Galactitol 2-dehydrogenase
... In enzymology, a galactitol 2-dehydrogenase (EC 1.1.1.16) is an enzyme that catalyzes the chemical reaction galactitol + NAD+ D-tagatose + NADH + H+ Thus, the two substrates of this enzyme are ...
Galactokinase - Disease Relevance
... In lens cells of the human eye, aldose reductase converts galactose to galactitol ... is not being catabolized to glucose due to a galactokinase mutation, galactitol accumulates ... This galactitol gradient across the lens cell membrane triggers the osmotic uptake of water, and the swelling and eventual apoptosis of lens cells ensues ...
Galactosemic Cataract - Galactitol's Harmful Influence
... that the lens’s retention of dulcitol, synonymous for galactitol, induces this osmotic swelling in the galactosemic cataract ... significant amounts of the sugar to its galactitol form ... is able to dip into this galactose reservoir and synthesize significant amounts of galactitol ...
Galactosemia - Accumulation of Galactose - Reduction To Galactitol
... aldose reductase reduces galactose to its sugar alcohol form, galactitol ... Galactitol, however, is not a suitable substrate for the next enzyme in the polyol pathway, polyol dehydrogenase ... Thus, galactitol accumulates in body tissues and is excreted in the urine of galactosemic patients ...