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Test ID CTSU Ceramide Trihexosides and Sulfatides, Random, Urine


Necessary Information


Biochemical Genetics Patient Information (T602, in Special Instructions) is recommended. This information aids in providing a more thorough interpretation of results. Send information with specimen.



Specimen Required


Patient Preparation: Baby wipes or wipes containing soaps and lotions should not be used prior to urine collection because these may interfere with results.

Supplies: Aliquot Tube, 5 mL (T465)

Collection Container/Tube: Plastic, 5-mL urine tube

Specimen Volume: 2 mL

Collection Instructions: Collect a first-morning, random urine specimen.

Specimen Stability Information: Refrigerated (preferred) 45 days/Ambient 45 days/Frozen 19 months


Forms

Biochemical Genetics Patient Information (T602) in Special Instructions

Useful For

Identifying patients with Fabry disease

 

Identifying patients with metachromatic leukodystrophy

 

Identifying patients with saposin B deficiency

 

Identifying patients with multiple sulfatase deficiency

 

Identifying patients with mucolipidosis II (I-cell disease)

Method Name

Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS)

Reporting Name

Ceramide Trihex and Sulfatide, U

Specimen Type

Urine

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 45 days
  Ambient  45 days
  Frozen 

Clinical Information

Urinary excretion of ceramide trihexosides (CT) can be suggestive of Fabry disease, while excretion of sulfatide with or without CT can be suggestive of metachromatic leukodystrophy, multiple sulfatase deficiency, mucolipidosis II (I-cell disease), or saposin B deficiency.

 

Fabry disease is an X-linked recessive lysosomal storage disorder caused by a deficiency of the enzyme alpha-galactosidase A (alpha-Gal A). Affected individuals accumulate glycosphingolipids in the lysosomes throughout the body, in particular, the kidney, heart, and brain. Severity and onset of symptoms are dependent on the amount of residual enzyme activity. Symptoms may include acroparesthesias (pain crises), multiple angiokeratomas, reduced or absent sweating, corneal opacity, renal insufficiency leading to end-stage renal disease, and cardiac and cerebrovascular disease. There are renal and cardiac variant forms of Fabry disease that may be underdiagnosed. Female patients who are carriers of Fabry disease can have clinical presentations ranging from asymptomatic to severely affected, and they may have alpha-Gal A activity in the normal range. Individuals with Fabry disease, regardless of the severity of symptoms, may show an increased excretion of CT in urine.

 

Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disorder most commonly caused by a deficiency of the arylsulfatase A enzyme. Various sulfatides accumulate in the brain, nervous system, and visceral organs including the kidney and gallbladder and are excreted in the urine. Based on age of onset, the 3 clinical forms of MLD are late-infantile, juvenile, and adult, with late-infantile being the most common. All result in progressive neurologic changes and leukodystrophy demonstrated on magnetic resonance imaging. Symptoms may include hypotonia, clumsiness, diminished reflexes, slurred speech, behavioral problems, and personality changes. Individuals with MLD show an increased urinary excretion of sulfatides without CT.

 

Saposin B deficiency is a rare cause of MLD with features that mimic MLD due to arylsulfatase A deficiency. However, individuals with saposin B deficiency have normal arylsulfatase A activity. Individuals with saposin B deficiency typically have an increased urinary excretion of both sulfatides and CT.

 

Low arylsulfatase A activity has been found in some clinically normal parents and other relatives of MLD patients. Individuals with this "pseudodeficiency" have been recognized with increasing frequency among patients with other apparently unrelated neurologic conditions as well as among the general population. This has been associated with a fairly common alternation in the arylsulfatase A gene (ARSA), which leads to low expression of the enzyme (5%-20% of normal). These individuals do not have metachromatic deposits in peripheral nerve tissues, and their urine sulfatides content is normal.

 

Multiple sulfatase deficiency (MSD) is a rare autosomal recessive disorder caused by a defect in SUMF1, which is required for post-translational activation of the family of 17 sulfatase enzymes, including arylsulfatase A and B. The clinical features of MSD resemble those of late-infantile MLD. Dysmorphic features similar to the mucopolysaccharidoses and ichthyosis as seen in steroid sulfatase deficiency are also common. Individuals with MSD typically have an increased urinary excretion of sulfatides as well as increased urinary glycosaminoglycans (test ID: MPSSC / Mucopolysaccharides Screen, Random, Urine).

 

Mucolipidosis II, also known as I-cell disease, is a rare autosomal recessive disorder with features of both mucopolysaccharidoses and sphingolipidoses. I-cell disease is a progressive disorder characterized by congenital or early infantile manifestations including coarse facial features, short stature, skeletal anomalies, cardio- and hepatomegaly, and developmental delays. Individuals with I-cell disease have abnormal oligosaccharide profiles (test ID: OLIGU / Oligosaccharide Screen, Random, Urine) and may show an increased urinary excretion of both CT and sulfatides.

Reference Values

An interpretive report will be provided.

Interpretation

The pattern of ceramide trihexosides or sulfatide excretion will be described. A normal pattern of excretion suggests absence of these diseases (see Cautions).

 

Evidence of ceramide trihexoside accumulation suggests decreased or deficient alpha-galactosidase activity. See Fabry Disease Testing Algorithm in Special Instructions.

 

Evidence of sulfatide accumulation suggests decreased or deficient arylsulfatase A activity. Follow-up with the specific enzyme assay is recommended:

-ARSAW / Arylsulfatase A, Leukocytes

-ARSU / Arylsulfatase A, 24 Hour, Urine

 

To exclude multiple sulfatase deficiency (MSD), determination of I2SW / Iduronate-2-Sulfatase, Whole Blood (or I2SBS / Iduronate-2-Sulfatase, Blood Spot) is recommended.

 

Evidence of both ceramide trihexoside and sulfatide accumulation suggests a diagnosis of mucolipidosis II (I-cell disease) or saposin B deficiency. Follow-up testing to rule-out I-cell disease may include molecular analysis of the GNPTAB gene or measurement of serum hydrolases (test ID: NAGS / Hexosaminidase A and Total Hexosaminidase, Serum)

 

Molecular genetic testing is required to confirm saposin B deficiency.

 

See Lysosomal Storage Disorders Diagnostic Algorithm, Part 2 in Special Instructions

Clinical Reference

1. Desnick RJ, Ioannou YA, Eng CM: a-Galactosidase A Deficiency: Fabry Disease. In The Online Metabolic and Molecular Bases of Inherited Disease. Edited by D Valle, AL Beaudet, B Vogelstein, et al. 2014. Accessed September 27, 2019. Available at http://ommbid.mhmedical.com/content.aspx?bookid=971&sectionid=62644837

2. Kuchar L, Ledvinova J, Hrebicek M, et al: Prosaposin deficiency and saposin B deficiency (activator-deficient metachromatic leukodystrophy): report on two patients detected by analysis of urinary sphingolipids and carrying novel PSAP gene mutations. Am J Med Genet A 2009 Feb 15;149A(4):613-621

3. Mehta A, Hughes DA: Fabry disease. In GeneReviews Edited by RA Pagon, MP Adam, HH Ardinger, et al. Accessed 6/19/2017. Available at www.ncbi.nlm.nih.gov/books/NBK1828

4. Schlotawa L, Ennemann EC, Radhakrishnan K, et al: SUMF1 mutations affecting stability and activity of formylglycine generating enzyme predict clinical outcome in multiple sulfatase deficiency. Eur J Hum Genet 2011;19:253-261

5. Gieselmann V, Ingeborg K: Metachromatic Leukodystrophy. In The Online Metabolic and Molecular Bases of Inherited Disease. Edited by D Valle, S Antonarakis, A Ballabio, et al. McGraw-Hill. Accessed September 27, 2019.Available at http://ommbid.mhmedical.com/content.aspx?bookid=2709&sectionid=225546629

6. Leroy JG, Cathey S, Friez MJ: GNPTAB-Related Disorders. In GeneReviews Edited by RA Pagon, MP Adam, HH Ardinger, et al. Accessed January 3, 2020. Available at www.ncbi.nlm.nih.gov/books/NBK1828

Day(s) and Time(s) Performed

Varies

Analytic Time

8 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

83789

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CTSU Ceramide Trihex and Sulfatide, U 59462-2

 

Result ID Test Result Name Result LOINC Value
606148 Interpretation 59462-2
606149 Reviewed By 18771-6