The protocol enables sequencing of 255 kb DNA from 94 genes including MLHI, MSH2, MSH6, and
PMS2, as well as 284 single nucleotide polymorphisms using 4000 80-mer probes designed from the human NCBI2137/hgl9 reference genome.
The surgical specimens of all newly diagnosed patients with endometrial cancer should undergo IHC staining for the mismatch repair proteins MLH1, MSH2, MSH6, and
PMS2. If loss of MLH1 is noted on IHC staining, the patient should undergo promoter hypermethylation testing because that can be seen in 10% to 20% of sporadic endometrial cancers.
The invasive tumor cells demonstrate loss of normal MLH1 and
PMS2 protein expression, with retention of normal MSH2 and MSH6 protein expression.
By this analysis, SureSelect had 7 genes [SDHD, TGFBR2 (transforming growth factor, 3 receptor II [70/80 kDa]), GLA (galactosidase, a), SDHC(succinate dehydrogenase complex, subunit C, integral membrane protein, 15 kDa), COL3A1 (collagen, type III, a1),
PMS2, PSCK9] for which >50% of HGMD variant locations had inadequate coverage.
Wehner et al., "Nine novel pathogenic germline mutations in MLH1, MSH2, MSH6 and
PMS2 in families with Lynch syndrome," Acta Oncologica, vol.
Because of this difficulty, immunohistochemical screening of CRCs has an important role in identifying families with
PMS2 mutations.
Lynch syndrome (LS) is an inherited cancer syndrome characterized by a very high incidence of colorectal cancer at an early age It is caused by germline mutations in genes coding for DNA mismatch repair enzymes, most commonly mutL homolog 1 (MLH1), [9] mutS homolog 2 (MSH2), mutS homolog 6 (MSH6), and postmeiotic segregation increased 2 (
PMS2) (9, 10).
The test under development is designed to identify a genetic predisposition to HNPCC by analysing specific DNA mismatch repair genes, including MSH2, MLH1, MSH6 and
PMS2, by molecular combing, a novel technology that enables the direct visualisation of individual DNA molecules.
Approximately 15% of colorectal cancers (CRCs) display MSI owing either to epigenetic silencing of MLH1 or approximately 2%-3% of all CRCs which are caused by germline mutations in one of the mismatch repair genes (MLH1, MSH2, MSH6, and
PMS2).