A study of galactokinase
and glucose 4-epimerase from normal and galactosemic skin fibroblasts.
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).
(EC188.8.131.52), galactose-1-phosphateuridyltransferase (GALT,3 EC 184.108.40.206), and uridine diphosphate galactose 4'-epimerase (EC 220.127.116.11) 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).