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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed February 2013

What is the official name of the ARSA gene?

The official name of this gene is “arylsulfatase A.”

ARSA is the gene's official symbol. The ARSA gene is also known by other names, listed below.

What is the normal function of the ARSA gene?

The ARSA gene provides instructions for making the enzyme arylsulfatase A. This enzyme is located in cellular structures called lysosomes, which are the cell's recycling centers. Within lysosomes, arylsulfatase A helps process substances known as sulfatides. Sulfatides are a subgroup of sphingolipids, a category of fats that are important components of cell membranes. Sulfatides are abundant in the nervous system's white matter, consisting of nerve fibers covered by myelin. Myelin, made up of multiple layers of membranes, insulates and protects nerves.

How are changes in the ARSA gene related to health conditions?

metachromatic leukodystrophy - caused by mutations in the ARSA gene

More than 110 mutations that cause metachromatic leukodystrophy, a disorder that causes deterioration of nervous system functions, have been identified in the ARSA gene. These mutations greatly reduce the activity of arylsulfatase A. Severe disruption in arylsulfatase A activity interferes with the breakdown of sulfatides. As a result, these substances can accumulate to toxic levels in the nervous system. The buildup of sulfatides gradually destroys the cells that produce myelin, the covering that protects nerves and promotes the efficient transmission of nerve impulses. Destruction of myelin leads to the loss of white matter (leukodystrophy) and impairment of nervous system function, resulting in the signs and symptoms of metachromatic leukodystrophy.

In some cases, individuals with very low arylsulfatase A activity show no signs or symptoms of metachromatic leukodystrophy. This condition, called pseudoarylsulfatase deficiency, seems to be caused by specific variations of the ARSA gene. These variations are present in as many as 5 to 10 percent of Europeans and North Americans.

Where is the ARSA gene located?

Cytogenetic Location: 22q13.33

Molecular Location on chromosome 22: base pairs 50,622,754 to 50,628,173

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The ARSA gene is located on the long (q) arm of chromosome 22 at position 13.33.

The ARSA gene is located on the long (q) arm of chromosome 22 at position 13.33.

More precisely, the ARSA gene is located from base pair 50,622,754 to base pair 50,628,173 on chromosome 22.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about ARSA?

You and your healthcare professional may find the following resources about ARSA helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the ARSA gene or gene products?

  • cerebroside 3-sulfatase
  • Cerebroside-3-sulfate 3-sulfohydrolase
  • Cerebroside-Sulfatase
  • MLD
  • sulfatidase

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding ARSA?

breakdown ; cell ; deficiency ; enzyme ; gene ; leukodystrophy ; nervous system ; sulfate ; toxic ; white matter

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Basic Neurochemistry (sixth edition, 1999): Lysosomal Disease (
  • Cesani M, Capotondo A, Plati T, Sergi LS, Fumagalli F, Roncarolo MG, Naldini L, Comi G, Sessa M, Biffi A. Characterization of new arylsulfatase A gene mutations reinforces genotype-phenotype correlation in metachromatic leukodystrophy. Hum Mutat. 2009 Oct;30(10):E936-45. doi: 10.1002/humu.21093. (
  • Essentials of Glycobiology (first edition, 1999): Glycosphingolipid Degradation (
  • Gieselmann V, Krägeloh-Mann I. Metachromatic leukodystrophy--an update. Neuropediatrics. 2010 Feb;41(1):1-6. doi: 10.1055/s-0030-1253412. Epub 2010 Jun 22. Review. (
  • Grossi S, Regis S, Rosano C, Corsolini F, Uziel G, Sessa M, Di Rocco M, Parenti G, Deodato F, Leuzzi V, Biancheri R, Filocamo M. Molecular analysis of ARSA and PSAP genes in twenty-one Italian patients with metachromatic leukodystrophy: identification and functional characterization of 11 novel ARSA alleles. Hum Mutat. 2008 Nov;29(11):E220-30. doi: 10.1002/humu.20851. (
  • Lugowska A, Płoski R, Włodarski P, Tylki-Szymańska A. Molecular bases of metachromatic leukodystrophy in Polish patients. J Hum Genet. 2010 Jun;55(6):394-6. doi: 10.1038/jhg.2010.25. Epub 2010 Mar 26. (
  • NCBI Gene (
  • Poeppel P, Habetha M, Marcão A, Büssow H, Berna L, Gieselmann V. Missense mutations as a cause of metachromatic leukodystrophy. Degradation of arylsulfatase A in the endoplasmic reticulum. FEBS J. 2005 Mar;272(5):1179-88. (
  • Rauschka H, Colsch B, Baumann N, Wevers R, Schmidbauer M, Krammer M, Turpin JC, Lefevre M, Olivier C, Tardieu S, Krivit W, Moser H, Moser A, Gieselmann V, Zalc B, Cox T, Reuner U, Tylki-Szymanska A, Aboul-Enein F, LeGuern E, Bernheimer H, Berger J. Late-onset metachromatic leukodystrophy: genotype strongly influences phenotype. Neurology. 2006 Sep 12;67(5):859-63. (
  • Shukla P, Vasisht S, Srivastava R, Gupta N, Ghosh M, Kumar M, Sharma R, Gupta AK, Kaur P, Kamate M, Gulati S, Kalra V, Phadke S, Singhi P, Dherai AJ, Kabra M. Molecular and structural analysis of metachromatic leukodystrophy patients in Indian population. J Neurol Sci. 2011 Feb 15;301(1-2):38-45. doi: 10.1016/j.jns.2010.11.007. Epub 2010 Dec 16. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: February 2013
Published: February 8, 2016