Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

ARSAK
61260
ASFR
80375
Gieselmann V: Structure of the arylsulfatase A gene. Eur J Biochem 1990 Aug 17;191(3):627-631 4.
Polten A, Fluharty AL, Fluharty CB, et al: Molecular basis of different forms of metachromatic
leukodystrophy. N Engl J Med 1991 Jan 3;324(1):18-22
ARSA Gene, Known Mutation
Clinical Information: Metachromatic leukodystrophy (MLD) is a rare autosomal recessive condition
caused by mutations in the arylsulfatase A gene (ARSA). The incidence of MLD is approximately
1:40,000 to 1:160,000, and the estimated carrier frequency in the general population is 1:100 to 1:200.
MLD is characterized by the accumulation of cerebroside sulfate, which causes progressive demyelination
and the loss of white matter. There is a variable age of onset. In the early onset form, symptoms appear in
the first 1 to 2 years of life and include deterioration of skills such as walking and speaking. In the
juvenile form, symptoms can appear between 4 years of age and the age of sexual maturity, and can
include a decline in school performance and behavioral problems. Adults can present with a decline in
school or job performance, substance abuse, and emotional lability. The diagnosis is suspected in
individuals with progressive neurologic dysfunction and molecular resonance imaging evidence of
leukodystrophy. The ARSA gene is located on chromosome 22 and has 8 exons. The following 4
mutations, c.459+1G>A, c.1204+1G>A, p.Pro426Leu, and p.Ile179Ser, account for 25% to 50% of
mutations in the central and western European populations. The recommended first-tier tests to screen for
MLD are biochemical tests that measure arylsulfatase A enzyme activity in leukocytes and urine
ARST/8778 Arylsulfatase A, Leukocytes and ARSU/8777 Arylsulfatase A, Urine. However, arylsulfatase
A enzyme assays cannot distinguish between MLD and ARSA pseudodeficiency, a clinically benign
condition that leads to low in vitro ARSA levels, but it is found in 5% to 20% of the normal population.
Thus, the diagnosis of MLD must be confirmed by molecular analysis of the ARSA gene.
Useful For: Carrier testing of individuals with a family history of metachromatic leukodystrophy
(MLD) Diagnostic confirmation of MLD when familial mutations have been previously identified
Interpretation: An interpretive report will be provided.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Biffi A, Cesani M, Fumagalli F, et al: Metachromatic
leukodystrophy-mutation analysis provides further evidence of genotype-phenotype correlation. Clin
Genet 2008 Oct;74(4):349-357 2. Gieselmann V, Krageloh-Mann I: Metachromatic leukodystrophy-an
update. Neuropediatrics 2010 Feb;41(1):1-6, Epub 2010 Jun 22 3. Kreysing J, von Figura K, Gieselmann
V: Structure of the arylsulfatase A gene. Eur J Biochem 1990 Aug 17;191(3):627-631 4. Polten A,
Fluharty AL, Fluharty CB, et al: Molecular basis of different forms of metachromatic leukodystrophy. N
Engl J Med 1991 Jan 3;324(1):18-22
Arsenic Fractionation, 24 Hour, Urine
Clinical Information: Arsenic (As) exists in a number of different forms; some are toxic, while
others are not. The toxic forms are the inorganic species of As(+3) (As-III), As(+5) (As-V), and their
partially detoxified metabolites, monomethylarsine and dimethylarsine. As-III is more toxic than As-V
and both are more toxic than mono- and dimethylarsine. The biologic half-life of inorganic arsenic is 4 to
6 hours, while the biologic half-life of the methylated metabolites is 20 to 30 hours. Target organs of
As-III-induced effects are the heart, gastrointestinal tract, skin and other epithelial tissues, kidney, and
nervous system. Inorganic arsenic is carcinogenic to humans. Symptoms of chronic poisoning, called
arseniasis, are mostly insidious and nonspecific. The gastrointestinal tract, skin, and central nervous
system are usually involved. Nausea, epigastric pain, colic abdominal pain, diarrhea, and paresthesias of
the hands and feet can occur. Nontoxic, organic forms of arsenic are present in many foods.
Arsenobetaine and arsenocholine are the 2 most common forms of organic arsenic found in food. The
most common foods that contain significant concentrations of organic arsenic are shellfish and other
predators in the seafood chain (cod, haddock, etc). Some meats such as chicken that have been fed on
seafood remnants may also contain the organic forms of arsenic. Following ingestion of arsenobetaine and
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