PMS2 Comprehensive Analysis

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, and MSH6, which are involved in DNA mismatch repair. 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, 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).

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