Galactokinase deficiency, also known as Galactosemia type 2 or GALK deficiency.
Galactokinase deficiency (GKD) is an inherited disorder of galactose metabolism. It is characterized by galactosuria and galactosemia that is caused by a deficiency of the galactokinase enzyme functioning on metabolic galactose to the glucose conversion pathway of Leloir. The disorder has an autosomal recessive way. The sign in affected children is the pattern of cataracts, due to production of galactitol in the lens of the eye. Cataracts can present as a failure to increase a social smile and failure to visually track moving objects.
Classical galactosaemia is the more severe disease and occurs from deficiency of galactose 1-phosphate uridyl transferase. The predominant feature of GKD is bilateral cataracts without liver, kidney, and brain damage as seen in galactose-1-phosphate uridyltransferase deficiency. Affected patients excrete surplus galactose in the urine and also add galactose and galactose 1-phosphate in the blood. There is an early neonatal presentation with failure to thrive, vomiting and liver disease, but these early signs are reversed when the infant is placed on a galactose-free diet. The frequency is about 1 in 70,000.
Galactokinase deficiency galactosaemia is a much rarer illness than classical galactosaemia, and the only reliable clinical features are cataracts, occurring either before or just after birth. It is possible that heterozygotes for the condition expand cataracts in later life, and the laboratory is sometimes asked to test adults for intermediate activity. This disorder is distributed similarly between sexes. Treatment may be provided on an outpatient basis. Cataracts may need surgical removal. Diet is also benefial this deficiency. Diet is the foundation of therapy. Removal of lactose and galactose sources suffices for perfect therapy.
