MLH1/MSH2/MSH6/PMS2 Comprehensive Analysis

CPT: 81292; 81295; 81298; 81317
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Test Details

Synonyms

  • Lynch Syndrome

Test Includes

This comprehensive test includes both Sanger sequencing and deletion/duplication analysis by MLPA of the MLH1, MSH2, MSH6, and PMS2 genes. The sequencing portion of this test covers all coding nucleotides 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. The deletion/duplication analysis can detect single exon, multi-exon, and full gene deletions or duplications.

Use

Can confirm a clinical diagnosis of HNPCC and allow early diagnosis in family members, guiding preventive measures. Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal-dominant, genetically heterogeneous syndrome caused by heterozygous mutations in mismatch repair genes (MMR). HNPCC is estimated to account for 4% to 6% of colorectal cancer and is characterized by early onset, a predominant proximal location of colon cancer, multiple primary cancers, and significantly improved survival when compared stage for stage to sporadic colon cancer survival rates. HNPCC has been linked to mutations in the genes MLH1, MSH2, PMS2, MSH6, and EPCAM. Genetic testing can confirm the diagnosis of HNPCC and can also identify presymptomatic individuals among the patient's relatives.

Limitations

Sequencing cannot detect variants in regions not covered by this analysis, including noncoding or deep intronic variants and may not reliably detect changes in repetitive elements, such as microsatellite repeats. Sequencing may not detect mosaic variants, inversions, or other genomic rearrangements such as transposable element insertions. Sequence analysis may also be affected by allele drop-out due to the presence of a rare variant under a primer site or homopolymeric regions. The method does not allow any conclusion as to whether two heterozygous variants are present on the same or on different chromosome copies.

Copy number variations are assessed by multiple-ligation- probe amplification assay (MLPA) to detect gross deletions and duplications. Copy number analyses are designed to detect single exon, multi-exon, and full gene deletions or duplications. These analyses may not detect certain genomic rearrangements, such as translocations (balanced or unbalanced), inversions, or some partial exon rearrangements. This assay cannot determine exact breakpoints of deletions or duplications detected.

The presence of pseudogenes can interfere with the ability to detect variants in certain genes. For example, deletion/ duplication analysis of PMS2 exons 11-15, among others, is complicated by the highly homologous PMS2CL pseudogene. Deletions/duplications in PMS2CL have not been associated with Lynch syndrome, however this assay may not be able to determine if a deletion/duplication affects PMS2 or PMS2CL. This test is not intended to detect somatic variants. Bone marrow transplantation, recent blood transfusion and active hematological malignancies may affect the outcome of these results. Please contact LabCorp to discuss testing options at 1-800-345-GENE.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

Methodology

DNA sequencing and multiplex ligation-dependent probe amplification (MLPA)

Specimen Requirements

Specimen

Whole blood

Volume

7 mL

Minimum Volume

4 mL

Container

Lavender-top (EDTA) tube

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Container broken or leaking; container not labeled; improper anticoagulant

Clinical Information

References

Evans JT, Vana J, Aronoff BL, Baker HW, Murphy GP. Management and survival of carcinoma of the colon: Results of a national survey of the American College of Surgeons. Ann Surg. 1978 Dec;188(6):716-720.736649
Hutter P, Wijnen J, Rey-Berthod C, et al. An MLH1 haplotype is over-represented on chromosomes carrying an HNPCC predisposing mutation in MLH1.J Med Genet. 2002 May;39(5):323-327.12011148
Kohlmann W, Gruber SB. Lynch syndrome. In: Pagon RA, Adam MP, Ardinger HH, et al, eds. GeneReviews®. 2004 Feb 5; Seattle, Wash: University of Washington;1993-2014. Available at: http://www.ncbi.nlm.nih.gov/books/NBK1211/.20301390
Online Mendelian Inheritance in Man (OMIM™). Colorectal cancer, hereditary nonpolyposis, type 8; HNPCC8. Baltimore, Md: Johns Hopkins University. Available at: http://www.ncbi.nlm.nih.gov/omim/613244.
Online Mendelian Inheritance in Man (OMIM™). Lynch syndrome I. Baltimore, Md: Johns Hopkins University. Available at: http://www.ncbi.nlm.nih.gov/omim/120435.
Online Mendelian Inheritance in Man (OMIM™). MutL, E coli, homolog of, 1; MLH1. Baltimore, Md: Johns Hopkins University. Available at: http://www.ncbi.nlm.nih.gov/omim/120436.
Online Mendelian Inheritance in Man (OMIM™). MutS, E coli, homolog of, 2; MSH2. Baltimore, Md: Johns Hopkins University. Available at: http://www.ncbi.nlm.nih.gov/omim/609309.
Online Mendelian Inheritance in Man (OMIM™). Postmeiotic segregation increased, S cerevisiae, 2; PMS2. Baltimore, Md: Johns Hopkins University. Available at: http://www.ncbi.nlm.nih.gov/omim/600259.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
511700 MLH1/MSH2/MSH6/PMS2 Comp 511699 Specimen Type 31208-2
511700 MLH1/MSH2/MSH6/PMS2 Comp 511698 Result 79570-8
511700 MLH1/MSH2/MSH6/PMS2 Comp 511697 Director Review 72486-4
511700 MLH1/MSH2/MSH6/PMS2 Comp 511696 Tracking N/A
511700 MLH1/MSH2/MSH6/PMS2 Comp 512123 PDF 80563-0

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CPT Statement/Profile Statement

The LOINC® codes are copyright © 1994-2018, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf