Defective GALK1 does not phosphorylate Gal

Stable Identifier
Reaction [transition]
Homo sapiens
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Cytosolic galactokinase (GALK1) catalyses the first step in the Leloir pathway of galactose metabolism. GALK1 catalyses the phosphorylation of D-galactose (Gal) to form D-galactose 1-phosphate (Gal1P). Defects in GALK1 can cause Galactosemia II (GALCT2; MIM:230200), an autosomal recessive deficiency characterised by congenital cataracts during infancy and presenile cataracts in the adult population. Galactitol accumulation in the lens is the cause of these cataracts. Mutations causing GALCT2 include V32M, E80*, P28T, Q382* and R256W (Stambolian et al. 1995, Kalaydjieva et al. 1999, Kolosha et al 2000, Bayarchimeg et al. 2012). There is a wide spectrum of severity and age of onset. However, beyond cataract formation, no long-term complications have been documented (Bosch et al. 2002, Timson & Reece 2003).

Literature References
PubMed ID Title Journal Year
10790206 Novel mutations in 13 probands with galactokinase deficiency

Stambolian, D, Gitzelmann, R, Shih, L, Saborio, M, Casco, T, Ledee, D, de Cespedes, C, Tedesco, T, Trejos, R, Huang, K, Anoia, E, Mitelmann, O, Skach, W, Buist, N, Kolosha, V

Hum. Mutat. 2000
10521295 A founder mutation in the GK1 gene is responsible for galactokinase deficiency in Roma (Gypsies)

Tournev, I, Markov, A, Gitzelmann, R, Yanakiev, P, Jordanova, A, Radeva, B, Angelicheva, D, Nedkova, V, Aneva, L, Kalaydjieva, L, Dye, D, Hallmayer, J, Savov, A, Kremensky, I, Bosshard, NU, Perez-Lezaun, A, Onengut, S

Am. J. Hum. Genet. 1999
12694189 Functional analysis of disease-causing mutations in human galactokinase

Reece, RJ, Timson, DJ

Eur. J. Biochem. 2003
12705493 Clinical features of galactokinase deficiency: a review of the literature

Wijburg, FA, Bakker, HD, van Gennip, AH, Wanders, RJA, Bosch, AM, van Kempen, JV

J. Inherit. Metab. Dis. 2002
23430910 Galactokinase deficiency in a patient with congenital hyperinsulinism

Flanagan, SE, Ismail, D, Hussain, K, Burk, D, Hogler, W, Bayarchimeg, M, Ellard, S, Kirk, J, Lam, A

JIMD Rep 2012
7670469 Cloning of the galactokinase cDNA and identification of mutations in two families with cataracts

Stambolian, D, Ai, Y, Nesburn, K, Rosenberg, M, Sathe, G, Bergsma, DJ, Sidjanin, D

Nat. Genet. 1995
Catalyst Activity

galactokinase activity of GALK1 mutants [cytosol]

Normal reaction
Functional status

Loss of function of GALK1 mutants [cytosol]

Name Identifier Synonyms
galactokinase deficiency DOID:14695 Galactosemia II
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