Division of Chemistry and Toxicology
	Galactosemia Unit

	Total Galactose
		Galactose is a sugar formed from dietary lactose. It is converted to galactose-1-phosphate and other metabolites by several enzymes, especially phosphogalactose uridyl transferase. A decrease or lack of the enzyme will cause elevated galactose and galactose-1-phosphate levels in the bloodstream.

 

	Principles of the Test
		The procedure manufactured by PerkinElmerWallac, Inc. is a fluormetric assay that simultaneously measures galactose and galactose-1-phosphate.  A fluorescent microplate reader and Galactose Test Kit make use of a fluorescent, galactose oxidase method in a microplate format.

 

	Enzyme Test: Galactose-1-Phosphate Uridyl Transferase
		Galactose-1-phosphate uridyl transferase (Gal-1-PUT) is one of the enzymes necessary to convert galactose-1-phosphate into glucose-1-phosphate. A decrease or lack of the enzyme will cause an elevated galactose level in the bloodstream. Classical galactosemia is a hereditary autosomal recessive disorder characterized by seizures, mental retardation, cataracts, and can be fatal. Most cases of galactosemia are due to partial deficiency or complete absence of the enzyme, Gal-1-PUT. Screening for the Gal-1-PUT enzyme in newborns is important for the early diagnosis and treatment of this disorder. If Gal-1-PUT deficiency is detected, infants should be placed on lactose free diets.

 

	Principles of the Test
		The procedure manufactured by PerkinElmerWallac, Inc. is an adaptation of the Beutler and Baluda procedure. The assay is based on the enhancement of the fluorescence of NADPH through a series of enzymatic reactions. This is a quantitative method that measures the enzyme galactose -1-phosphate uridyl transferase. Eleanor Stanley, MT (ASCP), Unit Manager 517-335-9599 stanleye@state.mi.us