A study of
galactokinase and glucose 4-epimerase from normal and galactosemic skin fibroblasts.
Galactokinase deficiency in eleven patients from eight Costa Rican families: Clinical and biochemical features (Poster).
In both
galactokinase and epimerase deficiency, children are generally asymptomatic and experience few or no ill effects from lack of the particular enzyme.
All but two study participants--both cataract sufferers--had
galactokinase levels considered normal.
Perhaps the absence of a correlation reflects differing enzyme activities, such as those of aldose reductase,
galactokinase, and/or galactose dehydrogenase.
Clinical features of
galactokinase deficiency: a review of the literature.
In the GALK assay, radiolabeled [[sup.14]C]-galactose catalysis to [[sup.14]C]-galactose-1-phosphate by endogenous
galactokinase is monitored and quantified by using densitometry after chromatographic separation (9).
Galactokinase (EC2.7.1.6), galactose-1-phosphateuridyltransferase (GALT,3 EC 2.7.7.12), and uridine diphosphate galactose 4'-epimerase (EC 5.1.3.2) are the 3 Leloir pathway enzymes responsible for the metabolism of galactose in man.
Increases in blood galactose (Gal) are also observed in other conditions, however: in the relatively rare
galactokinase (GALK) deficiency, which can have serious sequelae; in partial GALT deficiency, which has no clinical consequences; and in UDP-galactose-4-epimerase (GALE) deficiency, which has 1 common benign form and 1 extremely rare untreatable form with severe clinical outcomes (2, 3).
The Paigen and Beutler assays in combination are used by many screening laboratories (2) and can detect deficiencies in GALT,
galactokinase, and galactose epimerase; however, these methods have relatively high false-positive rates (3).