Galactosemia

A rare hereditary condition known as galactosemia involves defects in galac-tose-l-P uridylyltransferase that render the enzyme inactive. Toxic levels of... 

D-Galactose Hydrolysis of lactose. Can be changed to glucose in the liver and metabolized. Synthesized in the mammary gland to make the lactose of milk. A constituent of glycolipids and glycoproteins. Failure to metabolize leads to galactosemia and cataract. 

Kaufman FR, Devgan S Classical galactosemia a review. Endocrinologist 1995 5 189-... 

The Editors have striven, as in previous years, to include in the present volume reviews on greatly diversified subjects, all of timely importance. The article on mellituria in Volume 4 has been supplemented by a survey of galactosemia, and we expect to follow in future volumes with reviews of other inborn errors of metabolism or, in modern parlance, of molecular diseases. Likewise, the article on peptiduria supplements that on aminoaciduria in Volume 2 and that on microbiological assay of vitamins extends previous summaries on the nucleogenic vitamins. The haptoglobins lie on the borderline of hematology. 

Hyperchloremic acidosis has been noted in some cases (B7, K13) this is presumably due to defective tubular reabsorption of bicarbonate. Phosphate-losing rickets or marked hypokalemia have not as yet been reported in galactosemia, but some cases show roentgenological evidence of osteoporosis (M2), and Holzel et al. (H8) record low levels of serum potassium. 

Galactose, if fed in large amounts, causes cataracts in a number of other species, even though the other features of galactosemia are absent. These animal experiments are discussed below (Section 2.7) and enzymic mechanisms possibly related to the development of cataract in Section 3.3.3. 

Schwarz et al. (S10) showed that the erythrocytes of galactosemic subjects accumulated large amounts of galactose-l-phosphate, both in vivo and in vitro. This indicated that the metabolic block in galactosemia occurred at reaction (2) or reaction (3). Kalckar et al. (K7) and Isselbacher et al. (19) later showed that normal erythrocytes contained all 4 enzymes needed for reactions (1), (2), (3), and (4), and that in galactosemia there was virtually complete absence of galactose-l-phos-... 

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