STER - Clinical: Sterols, Plasma

Test Catalog

Test Name

Test ID: STER    
Sterols, Plasma

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

Investigation of possible desmosterolosis (desmosterol reductase deficiency), cerebrotendinous xanthomatosis, lathosterolosis, and sitosterolemia

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

Testing includes desmosterol, lathosterol, campesterol, cholestenol, and sitosterol for the investigation of disorders of sterol metabolism, including desmosterolosis, cerebrotendinous xanthomatosis, lathosterolosis, and sitosterolemia.

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

Cholesterol plays an essential role in many cellular and developmental processes. In addition to its role as a membrane lipid, it is the precursor to numerous molecules that play an important role in cell growth and differentiation, protein glycosylation, and signaling pathways. The biosynthesis of cholesterol and its subsequent conversion to other essential compounds is complex, involving a number of intermediates and enzymes. Disorders that result from a deficiency of these enzymes lead to an accumulation of specific intermediates and inhibit the formation of important biomolecules. Clinical findings common to cholesterol biosynthesis disorders include congenital skeletal malformations, dysmorphic facial features, psychomotor retardation, and failure to thrive.

 

Desmosterolosis (desmosterol reductase deficiency) is a very rare disorder of cholesterol biosynthesis with a clinical phenotype similar to that of Smith-Lemli-Opitz (SLO) syndrome (7-dehydrocholesterol reductase deficiency). To date, less than 10 cases of desmosterolosis have been described. Its biochemical marker is the elevation of desmosterol in plasma, tissue, and cultured cells.

 

Another very rare disorder of cholesterol biosynthesis is lathosterolosis caused by mutations in SC5DL (sterol 3-beta-hydroxysteroid-delta-5-desaturase). Less than 5 patients have been described to date, but the phenotype appears to be characterized by dysmorphic features, multiple congenital anomalies including those of limb and kidney, intellectual disability, and liver disease. Biochemical abnormalities include elevated lathosterol and transaminases, hyperbilirubinemia, and absent 7-dehydrocholesterol.

 

Sitosterolemia is a rare autosomal recessive disorder caused by mutations in the ATP-binding cassette (ABC) transporter genes, ABCG5 and ABCG8, which abnormally enhance the absorption of plant sterols and cholesterol from the intestines. Patients often present with hematologic abnormalities and tendon and tuberous xanthomas as well as premature coronary artery disease. A biochemical diagnosis of sitosterolemia is made by documenting elevations of the plant sterols sitosterol and campesterol in plasma or serum.

 

Cerebrotendinous xanthomatosis (CTX), also known as 27-hydroxylase deficiency, is an autosomal recessive sterol storage disease causing accumulation of cholestanol and cholesterol in most tissues and markedly increased levels of cholestenol in serum. Clinical symptoms, which are variable, develop gradually and can include early chronic diarrhea, followed by bilateral cataracts, tuberous and tendon xanthomas, early atherosclerosis, and progressive neurologic impairment such as ataxia, paraparesis, cerebellar ataxia, and dementia. CTX should be suspected in patients with tendon xanthomas and normal or elevated serum cholesterol, and considered in cases of unexplained juvenile cataracts.

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.

DESMOSTEROL

0.0-2.0 mg/L

 

LATHOSTEROL

0.0-3.0 mg/L

 

CAMPESTEROL

0.0-7.0 mg/L

 

SITOSTEROL

0.0-5.0 mg/L

 

CHOLESTANOL

0.0-5.0 mg/L

Interpretation Provides information to assist in interpretation of the test results

A quantitative report of the patient's sterol profile and a Biochemical Genetics consultant's interpretation is provided for each specimen.

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

Reference ranges were derived using fasting specimens from healthy individuals. Sitosterol and campesterol values may be mildly elevated in individuals whose diets include foods with high concentrations of plant sterols, such as some vegetable oils and infant formulas.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Zolotushko J, Flusser H, Markus B, et al: The desmosterolosis phenotype: spasticity, microcephaly and micrognathia with agenesis of corpus callosum and loss of white matter. European Journal of Human Genetics. 2011;19(9):942-946 doi:10.1038/ejhg.2011.74

2. Bjorkhem, I, et al: Inborn Errors in Bile Acid Biosynthesis and Storage of Sterols Other than Cholesterol. The Online Metabolic and Molecular Bases of Inherited Disease Eds. David Valle, et al: New York, NY: McGraw-Hill, 2014, Accessed April 24, 2017. Available at http://ommbid.mhmedical.com/content.aspx?bookid=971&sectionid=62638585

3. Lu K, Lee MH, Hazard S, et al: Two genes that map to the STSL locus cause sitosterolemia: genomic structure and spectrum of mutations involving sterolin-1 and sterolin-2, encoded by ABCG5 and ABCG8, respectively. Am J Hum Genet 2001 August;69(2):278-290

4. Pilo de la Fuente B, et al: Usefulness of cholestenol levels in the diagnosis and follow-up of patients with cerebrotendinous xanthomatosis. Neurologia 2011 26:397-404

5. Herman GE, Kratz L: Disorders of sterol synthesis: beyond Smith-Lemli-Optiz syndrome. Am J Med Genet C Semin Med Genet 2012;106C:301-321

Special Instructions and Forms Library of PDFs including pertinent information and consent forms, specimen collection and preparation information, test algorithms, and other information pertinent to test