Chapter 12 Galactose metabolism

Galactose is utilized as fuel in cells after being converted into glucose. Galactose is synthesized in mammary glands for production of lactose in milk.

12.1 Metabolism of galactose

12.2 Disorders of galactose metabolism

12.2.1 Galactokinase deficiency

Leads to increased levels of galactose in blood (galactosemia) and urine (galactosuria).Increased levels of galactose leads to formation of galactitol in lens which causes cataract.

12.2.2 Classical galactosemia

Occurs due to genetic defect in the enzyme Galactose 1-phosphate uridyltransferase. It leads to galactosemia and galactosuria. Increased levels of galactose causes cataract, and accumulation of galactose-1-phosphate damages brain, liver and kidney.

12.3 Practice exercises

1. Match the metabolic disorder with their enzyme defect

• "Hereditary fructose intolerance: Aldolase BFructokinaseGalactose 1-phosphate uridyl transferase"

• "Essential fructosuria: Aldolase BFructokinaseGalactose 1-phosphate uridyl transferase"

• "Classical galactosemia: Aldolase BFructokinaseGalactose 1-phosphate uridyl transferase"

2. Match the enzyme defect with their characteristic clinical feature

• "Hereditary fructose intolerance: CataractHypoglycaemiaHemolysis and anemiaPentosuriaHyperglycaemia"

• "Galactokinase deficiency: CataractHypoglycaemiaHemolysis and anemiaPentosuriaHyperglycaemia"

• "G6PD deficiency: CataractHypoglycaemiaHemolysis and anemiaPentosuriaHyperglycaemia"