Wilson Disease: ATP7B (Full Gene Sequencing)

CPT: 81406
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Test Details

Test Includes

This test covers all coding nucleotides of gene ATP7B, plus at least two and typically 20 flanking intronic nucleotides upstream and downstream of each coding exon, covering the conserved donor and acceptor splice sites, as well as typically 20 flanking nucleotides in the 5′ and 3′ UTR.

Use

Can confirm a clinical diagnosis of Wilson disease, detect carriers, and allow early diagnosis in family members, guiding prophylactic measures.

Limitations

This method does not reliably detect mosaic variants; large deletions; large duplications, inversions, or other rearrangements; or deep intronic variants. It may be affected by allele-dropout, it may not allow determination of the exact numbers of T/A or microsatellite repeats, and it does not allow any conclusion as to whether two heterozygous variants are present on the same or on different chromosome copies.

Results of this test are for investigational purposes only. The performance characteristics of this assay have been determined by LabCorp. The result should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.

Methodology

DNA sequencing

Reference Interval

Normal equals reference sequence or variants that are known or predicted to be benign; abnormal equals all other variants.

Additional Information

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism characterized by abnormal accumulation of copper in the liver, brain, and other organs. Wilson disease most typically first presents between the ages of 6 and 50 years, with acute or chronic liver disease (40% of affected), neurological movement disorders (40% of affected), or psychiatric disturbances such as depression or neurotic behaviors (20% of affected). Wilson disease has been linked to mutations in the gene ATP7B, which codes for a P-type copper-transporting ATPase. Genetic testing can confirm the diagnosis of Wilson disease and resolve equivocal biochemical test results. Once the mutations causing Wilson disease in a specific family have been identified, genetic testing for these mutations can also identify presymptomatic individuals among the patient's relatives, allowing preventive treatment. By distinguishing presymptomatic family members from heterozygous carriers, genetic testing can help to protect heterozygous carriers from unnecessary lifelong preventive treatment.

Specimen Requirements

Specimen

Whole blood; DNA is accepted (Call 800-345-4363 for DNA collection information.)

Volume

2 mL

Container

Lavender-top (EDTA) tube

Collection

Samples may be stored for brief periods at 4°C. Ship overnight at room temperature.

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Container broken or leaking; container not labeled or label not legible; improper anticoagulant

Clinical Information

Special Instructions

In cases in which a known mutation can be documented, the physician may prefer to order test 252806.

Test orders must include an attestation that the provider has the patient's informed consent for genetic testing. See sample physician office consent form: Consent for Genetic Testing. In the case of family tests (ie, known mutations), please submit the result report of the first patient tested in the family (the index case), if not performed at a LabCorp facility. Other family members are subsequently tested for the specific mutation found in the first patient tested.

References

Ala A, Borjigin J, Rochwarger A, Schilsky M. Wilson disease in septuagenarian siblings: Raising the bar for diagnosis. Hepatology. 2005 Mar; 41(3):668-670. 15723329
Cox DW, Roberts EA. Wilson disease. GeneReviews.http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=wilson Accessed June 28, 2010.
de Bie P, Muller P, Wijmenga C, Klomp LW. Molecular pathogenesis of Wilson and Menkes disease: Correlation of mutations with molecular defects and disease phenotypes. J Med Genet. 2007 Nov; 44(11):673-688. 17717039
Online Mendelian Inheritance in Man (OMIM™). Baltimore, Md: Johns Hopkins University, MIM N° 606882: Last updated November 14, 2007. http://omim.org/entry/606882 Accessed June 6, 2010.
Schilsky ML, Ala A. Genetic testing for Wilson disease: Availability and utility. Curr Gastroenterol Rep. 2010 Feb; 12(1): 57-61. 20425485
Wilson DC, Phillips MJ, Cox DW, Roberts EA. Severe hepatic Wilson's disease in preschool-aged children. J Pediatr. 2000 Nov; 137(5):719-722. 11060541

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
252803 Wilson's Disease: ATP7B 21626-7 252201 Routing 21626-7

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