Reference Work Entry

Encyclopedia of Molecular Mechanisms of Disease

pp 679-680

Galactokinase Deficiency

  • David J. TimsonAffiliated withSchool of Biological Sciences, Queen’s University Belfast
  • , Richard J. ReeceAffiliated withFaculty of Life Sciences, University of Manchester
  • , James B. ThodenAffiliated withDepartment of Biochemistry, University of Wisconsin
  • , Hazel M. HoldenAffiliated withDepartment of Biochemistry, University of Wisconsin


Galactosemia type II; Galk deficiency

Definition and Characteristics

Autosomal recessive inborn error in galactose metabolism leading to hypergalactosemia and cataract formation.


Overall estimates of homozygotes range from 1:100,000 to 1:1,000,000. Some mutations, however, have higher frequencies in particular populations such as the A198V mutation in Japanese, Korean and Chinese populations [1] and the P28T mutation in Roma and Bosnian populations [2,3].


GALK1 coding for galactokinase, localized on chromosome 17q24 [4].

Molecular and Systemic Pathophysiology

Galactokinase functions in normal galactose metabolism by catalyzing the MgATP-dependent phosphorylation of the C-1 hydroxyl group of α-d-galactose. Approximately 25 mutations (including base substitutions, base deletions, and larger deletions) have been reported in human galactokinase, which give rise to Type II galactosemi ...

This is an excerpt from the content