Galactolysis refers to the catabolism of galactose.
In the liver, galactose is converted through the Leloir pathway to glucose 6-phosphate in the following reactions:
galacto- uridyl phosphogluco- kinase transferase mutase gal --------> gal 1 P ------------------> glc 1 P -----------> glc 6 P ^ \ / v UDP-glc UDP-gal ^ / \___________/ epimerase
There are 3 types of galactosemia or galactose deficiencies:
|galactokinase deficiency||Galactokinase||Causes cataracts, which are treatable by restricting galactose from the diet.|
|UDPgalactose-4-epimerase deficiency||UDPgalactose-4-epimerase||Is extremely rare (only 2 reported cases). It causes nerve deafness.|
|Galactose-1-phosphate uridyl transferase deficiency||Galactose-1-phosphate uridyl transferase||Is the most problematic, as galactose-free diets are not effective in treating neurocognitive deficiencies (in particular language disorders such as verbal dyspraxia) and ovarian failure. If a galactose-free diet is administered, cataracts and acute symptoms such as kidney and liver failure respond immediately.|