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MLH1/MSH2/MSH6/PMS2 Comprehensive Analysis
- Lynch Syndrome
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.
Sequencing cannot detect variants in regions not covered by this analysis, such as variants in noncoding or deep intronic regions and may not reliably detect changes in repetitive elements, such as microsatellite repeats. Sequence analysis may also be affected by allele drop-out due to the presence of a rare variant under a primer site. MLPA is designed to detect single exon, multi-exon, and full gene deletions or duplications. MLPA may not detect certain genomic rearrangements, such as translocations, inversions, or some partial exon rearrangements. This assay cannot determine exact breakpoints of deletions or duplications detected. Mosaic variants are not reliably detected by either sequencing or MLPA. These analyses also cannot determine whether two or more heterozygous changes are located on the same or different chromosomes. Due to the presence of the pseudogene PMS2CL, which has not been associated with Lynch syndrome, this assay cannot determine the location, ie, in PMS2 or PMS2CL, of any large deletions or duplications of exons 12 to 15 of the PMS2 gene detected by deletion/duplication analysis.
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).
DNA sequencing and multiplex ligation-dependent probe amplification (MLPA)
Causes for Rejection
|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||511697||Director Review||72486-4|
|Reflex Table for Result|
|Order Code||Order Name||Result Code||Result Name||UofM||Result LOINC|