5 - 10 days
Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
MLH1B - MLH-1 Immunostain
MSH2B - MSH-2 Immunostain
MSH6B - MSH-6 Immunostain
PMS2B - PMS-2 Immunostain
SLIDEM - Slide Review, Mol Genetics
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Multiplex Polymerase Chain Reaction (PCR) with Capillary Electrophoresis
Microsatellite instability (MSI) is the change in length of a microsatellite allele due to either insertion or deletion of repeating units and a failure of the DNA mismatch repair (MMR) system to repair these replication errors. This genomic instability arises in a variety of human neoplasms where tumor cells have a decreased ability to faithfully replicate DNA. MSI is particularly associated with colorectal cancer, where 15-20% of sporadic tumors show MSI, in contrast to the more common chromosomal instability (CIN) phenotype, with MSI status being an independent prognostic indicator. MSI analysis is also clinically useful in identifying patients at increased risk of hereditary nonpolyposis colorectal cancer (HNPCC)/Lynch Syndrome, where a germline mutation of a MMR gene causes a familial predisposition to colorectal cancer.
Interpretive report provided.
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Both normal (non-neoplastic) and invasive neoplastic tissue are required for analysis. A formalin-fixed, paraffin-embedded tissue block is preferred but unstained, UNBAKED slides (5-8, 10-micron slides; 10-15 if few neoplastic cells are present) with associated H&E stained slide are also acceptable. The appropriate block/slides should contain an area with a high percentage of invasive neoplastic cells (for micro-/macro-dissection). Either the same block/slides or separate block/slides must contain an area of pure, non-neoplastic tissue of sufficient cellularity. Decalcified tissue or other fixatives will be accepted and the assay attempted, however these may result in failed testing due to degraded nucleic acid. Both blocks and slides should be stored at room temperature.