Pseudo arylsulfatase-A deficiency in healthy individuals: genetic and biochemical relationship to metachromatic leukodystrophy.

Abstract

Metachromatic leukodystrophy is a hereditary neurodegenerative disorder in man associated with deficient arylsulfatase-A activity (aryl-sulfate sulfohydrolase, EC 3.1.6.1). The same enzyme deficiency has been noted in clinically normal individuals, a condition known as pseudo arylsulfatase-A deficiency. With a nonselective method, somatic cell hybrids were obtained from cultured fibroblasts of these two types of individuals; the hybrids showed no restoration of arylsulfatase-A activity. Thus, metachromatic leukodystrophy and pseudo arylsulfatase-A deficiency are allelic conditions. Although these conditions cannot be distinguished by simple quantitative arylsulfatase-A activity assays, they can be differentiated with sucrose density gradient centrifugation, Cellogel electrophoresis, or isoelectric focusing in polyacrylamide gels. In each case, a small amount of activity with characteristics of arylsulfatase-A was found only from fibroblasts of pseudo arylsulfatase-A-deficient individuals and not from those of metachromatic leukodystrophy patients. This residual enzyme has the same pH optimum, heat stability, inhibitor sensitivity, and Km as the normal enzyme but slightly different isoelectric points. In conclusion, although pseudo arylsulfatase-A deficiency and metachromatic leukodystrophy have very different clinical outcomes, they are due to mutations of the same structural gene, coding for arylsulfatase-A. These two conditions can be differentiated now by simple electrophoretic analysis of the residual arylsulfatase-A activity.

• Authors: P L Chang, R G Davidson
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 80 Issue 23 Pg. 7323-7 (Dec 1983) ISSN: 0027-8424 [Print] United States
• PMID: 6580647 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Sulfatases
• Arylsulfatases

Topics

• Arylsulfatases (deficiency, genetics, metabolism)
• Cells, Cultured
• Clone Cells
• Fibroblasts (enzymology)
• Humans
• Hybrid Cells (enzymology)
• Kinetics
• Leukodystrophy, Metachromatic (enzymology, genetics)
• Reference Values
• Sulfatases (deficiency)