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Publisher Summary This chapter discusses the characteristics of fibroblasts cultured from patients with galactosemia or galactokinase deficiency. Galactosemia is a rare autosomal recessive disease characterized by milk intolerance. The acute symptoms following milk ingestion include vomiting, convulsions, jaundice, hepatosplenomegaly, and sometimes death. The chronic symptoms of the disease are cataracts and mental retardation. Virtually all the disagreeable features of galactosemia can be prevented or greatly attenuated by placing a newborn patient on a diet free of milk and related natural products. Heterozygotes again have intermediate levels of activity of the affected enzyme and are clinically normal. The enzyme deficiency can be demonstrated both in the erythrocytes and cultured fibroblasts of persons carrying the mutant gene. Growth experiments are performed by making replicate cultures of cells of each of the strains to be tested. Both normal and galactosemic strains are incubated concurrently in identical media. The reported assays of this enzyme activity in cultured fibroblasts are based either on spectrophotometry or on the use of a radioactive cosubstrate and the isolation of labeled product. Tedesco and Mellman have reported that the ratio of transferase to galactokinase activity is particularly helpful in assessing cell genotype at the transferase locus. |
