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Test ID: CTSA    
Ceramide Trihexosides and Sulfatides, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

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)

Genetics Test Information Provides information that may help with selection of the correct test or proper submission of the test request

 

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Urinary excretion of ceramide trihexosides and/or sulfatide can be suggestive of Fabry disease, 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). Reduced enzyme activity results in accumulation of glycosphingolipids in the lysosomes throughout the body, in particular, the kidney, heart, and brain. Severity and onset of symptoms are dependent on the 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. Females who are carriers of Fabry disease can have clinical presentations ranging from asymptomatic to severely affected, and 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 ceramide trihexoside in urine.

 

Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disorder caused by a deficiency of the arylsulfatase A enzyme, which leads to the accumulation of various sulfatides in the brain, nervous system, and visceral organs, including the kidney and gallbladder. The 3 clinical forms of MLD are late-infantile, juvenile, and adult, depending on age of onset. 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 typically show an increased excretion of sulfatides in urine.

 

Low arylsulfatase A activity has been found in some clinically normal parents and other relatives of MLD patients. These individuals do not have metachromatic deposits in peripheral nerve tissues, and their urine content of sulfatides is normal. 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 polymorphism in the arylsulfatase A gene, which leads to low expression of the enzyme (5%-20% of normal).

 

Saposin B deficiency is a rare autosomal recessive disorder with symptoms that mimic MLD. Age of onset dictates the clinical subtypes of saposin B deficiency. Individuals with saposin B deficiency have normal arylsulfatase A activity. In urine, individuals with saposin B deficiency have an increased excretion of sulfatides and may also show increased excretion of ceramide trihexosides.

 

Multiple sulfatase deficiency (MSD) is another rare autosomal recessive disorder that mimics the symptoms of MLD. In addition, individuals with MSD also may have clinical manifestations that resemble mucopolysaccharidoses. MSD results in deficiencies in all sulfatases including arylsulfatase A and B. Individuals with MSD have an increased excretion of sulfatides in their urine. 

 

Mucolipidosis II, also known as I-cell disease, is a rare autosomal recessive disorder with features of both mucopolysaccharidoses and sphingolipidoses. It is characterized by congenital or early infantile manifestations including coarse facial features, short stature, skeletal anomalies, cardio- and hepatomegaly, and developmental delays. This is a progressive disorder and death typically occurs in the first decade of life. Individuals with I-cell disease typically show an increased excretion of ceramide trihexosides and sulfatides in urine.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Interpretation Provides information to assist in interpretation of the test results

No evidence of ceramide trihexosides or sulfatide accumulation suggests normal enzyme activities. 

 

Evidence of ceramide trihexoside accumulation suggests decreased or deficient alpha-galactosidase activity. Follow-up testing with the specific enzyme assay is recommended:

-AGA / Alpha-Galactosidase, Leukocytes

-AGABS / Alpha-Galactosidase, Blood Spot

-AGAS / Alpha-Galactosidase, Serum

 

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

-ARSAW / Arylsulfatase A, Leukocytes

-ARST / Arylsulfatase A, Fibroblasts

-ARSU / Arylsulfatase A, 24 Hour, Urine

To exclude multiple sulfatase deficiency (MSD), simultaneous determination of ARSB / Arylsulfatase B, Fibroblasts and I2SW / Iduronate-2-sulfatase, Whole Blood (or I2SBS / Iduronate-2-sulfatase, Blood Spot) is recommended.

 

Evidence of both ceramide trihexoside and sulfatide accumulation suggests diagnosis of mucolipidosis II (I-cell disease) or saposin B deficiency. Follow-up testing to rule out I-cell disease may include:

-NAGS / Hexosaminidase A and Total Hexosaminidase, Serum

-AGAS / Alpha-Galactosidase, Serum, or ANAS / Alpha-N-Acetylglucosaminidase, Serum.

Molecular genetic testing is required to confirm saposin B deficiency. 

 

See Fabry Disease Testing Algorithm in Special Instructions.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Specific enzymatic assays should be used to confirm positive results.

 

In rare instances a normal excretion of ceramide trihexosides may be seen in individuals who are carriers of or affected with Fabry disease. If Fabry disease is clinically suspected, see Fabry Disease Testing Algorithm in Special Instructions for additional testing recommendations.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Desnick RJ, Ioannou YA, Eng CM: Chapter 150: Alpha-galactosidase A deficiency: Fabry disease. In The Metabolic Basis of Inherited Disease. Eighth edition. Edited by D Valle. AL Beaudet, B Vogelstein. New York, McGraw-Hill Book Company. Available from URL: www.ommbid.com. Accessed 02/21/2014

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. GeneReviews. Edited by RA Pagon, TD Bird, CR Dolan, et al. University of Washington, Seattle. Last updated October 2013

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. von Figura K, Gieselmann V, Jaeken J: Chapter 148: Metachromatic Leukodystrophy. In The Metabolic Basis of Inherited Disease. Eighth edition. Edited by D Valle. AL Beaudet, B Vogelstein. New York, McGraw-Hill Book Company. Available from URL: www.ommbid.com. Accessed 02/21/2014

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test