Home > A. Molecular pathology > galactose


Tuesday 25 November 2003


Galactan is a polymer of the sugar galactose. It is found in hemicellulose and can be converted to galactose by hydrolysis. Galactose solubility in water is 68.30 grams per 100 grams of water at 20–25° C.


It is also synthesized by the body, where it forms part of glycolipids and glycoproteins in several tissues.


Galactose and glucose are produced by hydrolysis of lactose by β-galactosidase. This enzyme is produced by the lac operon in Escherichia coli (E. coli).

In the liver, galactose is converted to glucose 6-phosphate.


- Galactosemia Galactokinase

  • Causes cataracts and mental retardation. If a galactose-free diet starts sufficiently early, the cataracts will regress without complications however neurological damage is permanent.

- 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


- Petry KG, Reichardt JK. The fundamental importance of human galactose metabolism: lessons from genetics and biochemistry. Trends Genet. 1998 Mar;14(3):98-102. PMID: 9540406