Galactose tolerance studies of individuals with reduced galactose pathway activity

The galactose tolerance of individuals with mutant genotypes affecting the activities of galactokinase (GALK) and galactose-1-phosphate uridylyltransferase (GALT) was examined. Genotypes studied were heterozygotes for the GALK and GALT forms of galactosemia, the Duarte-variant GALT, and Philadelphia...

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Bibliographic Details
Published in:American journal of human genetics 1975-11, Vol.27 (6), p.748-754
Main Authors: Mellman, W J, Rawnsley, B E, Nichols, C W, Needelman, B, Mennuti, M T, Malone, J, Tedesco, T A
Format: Article
Language:English
Subjects:
Cataract - complications
Female
Galactose - administration & dosage
Galactose - metabolism
Galactose - urine
Heterozygote
Humans
Infant, Newborn
Infusions, Parenteral
Phenotype
Phosphotransferases - deficiency
Pregnancy
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Summary:The galactose tolerance of individuals with mutant genotypes affecting the activities of galactokinase (GALK) and galactose-1-phosphate uridylyltransferase (GALT) was examined. Genotypes studied were heterozygotes for the GALK and GALT forms of galactosemia, the Duarte-variant GALT, and Philadelphia-variant GALK alleles. The measurements used were urinary concentration of galactose during pregnancy in adults and in infants from the newborn period through the first 5 months of life; the rate of elimination of an intravenous infusion of galactose; and slit-lamp examination of the lens for evidence of cataracts. No unusual urinary excretions of galactose were noted in any of the age groups studied. Intravenous galactose tolerance tests were normal in all but two women, a mother and daughter heterozygous for the GALK-deficient form of galactosemia (GALKG/GALKA). Six other GALKG/GALKA subjects had normal tolerance studies. The intrafamilial consistency and interfamilial differences in the galactose tolerance of GALKG/GALKA individuals suggest heterogeneity of the genes responsible for the GALK-deficient form of galactosemia. Although subclinical cataracts were observed in several individuals, their significance relative to the mutant genotype cannot be resolved with the available data.
ISSN:0002-9297
1537-6605