Uncertain pathogenicity of <i>MSH2</i> variants N127S and G322D challenges their classification

Ollila, Saara; Đermadi, Denis; Greenblatt, Marc S.; Nyström, Minna

doi:10.1002/ijc.23573

Cited by 7 publications

(20 citation statements)

References 37 publications

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“…Moreover, p.Gly322 is a conserved amino acid suggesting its importance. Irrespective of the recent study, where enhancer screens with the yeast homolog msh2 p.Gly317Asp did not yield enhancer mutations [Martinez and Kolodner, 2010] and our previous study, where the purified p.Gly322Asp variant did not show MMR deficiency [Ollila et al, 2008], here the total protein extract with over expressed MSH2 p.Gly322Asp individually and as a pair with p.Asp487Glu show a statistically significant decrease in repair efficiency. It is possible that the purification process has at least partly excluded structurally damaged heterodimers suggesting that the in vitro MMR assay performed with total extract is more reliable.…”

Section: Discussionmentioning

confidence: 62%

“…In the present study, of the eight analyzed VUS pairs, MSH2 p.Asn127Ser/p.Ala328Pro and MSH2 p.Gly322Asp/p.Asp487Glu show significantly decreased repair efficiency. In both pairs, one of the partners is a rare variation, whereas the other (p.Asn127Ser and p.Gly322Asp) is among the most frequently reported VUS in CRC [Hampel et al, 2006; Ollila et al, 2008]. Of these pairs, especially p.Asn127Ser/p.Ala328Pro suggests a concomitant contribution to the MMR deficiency.…”

Section: Discussionmentioning

confidence: 99%

“…MSH2 p.Asp487Glu has not been studied functionally before and, although the majority of the published data discusses p.Gly322Asp as a neutral polymorphism [Ollila et al, 2008; Martinez and Kolodner, 2010], it has also been hypothesized to be a low penetrance allele, supported by the functional analyses conducted with yeast assays [Drotschmann et al, 1999; Ellison et al, 2001]. Moreover, p.Gly322 is a conserved amino acid suggesting its importance.…”

Section: Discussionmentioning

confidence: 99%

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Mismatch repair analysis of inherited MSH2 and/or MSH6 variation pairs found in cancer patients

et al. 2012

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Mismatch repair (MMR) malfunction causes the accumulation of mismatches in the genome leading to genomic instability and cancer. The inactivation of an MMR gene (MSH2, MSH6, MLH1, or PMS2) with an inherited mutation causes Lynch syndrome (LS), a dominant susceptibility to cancer. MMR gene variants of uncertain significance (VUS) may be pathogenic mutations, which cause LS, may result in moderately increased cancer risks, or may be harmless polymorphisms. Our study suggests that an inherited MMR VUS individually assessed as proficient may, however, in a pair with another MMR VUS found in the same colorectal cancer (CRC) patient have a concomitant contribution to the MMR deficiency. Here, eight pairs of MMR gene variants found in cancer patients were functionally analyzed in an in vitro MMR assay. Although the other pairs do not suggest a compound deficiency, the MSH2 VUS pair c.380A>G/c.982G>C (p.Asn127Ser/p.Ala328Pro), which nearly halves the repair capability of the wild-type MSH2 protein, is presumed to increase the cancer risk considerably. Moreover, two MSH6 variants, c.1304T>C (p.Leu435Pro) and c.1754T>C (p.Leu585Pro), were shown to be MMR deficient. The role of one of the most frequently reported MMR gene VUS, MSH2 c.380A>G (p.Asn127Ser), is especially interesting because its concomitant defect with another variant could finally explain its recurrent occurrence in CRC patients.

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Section: Discussionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Mismatch repair analysis of inherited MSH2 and/or MSH6 variation pairs found in cancer patients

et al. 2012

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“…The remaining VUS for both genes were selected in an unbiased fashion and were predominantly derived from Dutch and Danish suspected LS patients. [Kolodner et al, 1999], 9 [Berends et al, 2002], 10 [Niessen et al, 2006], 11 [Woods et al, 2005], 12 [Belvederesi et al, 2008], 13 [Mastrocola and Heinen, 2010], 14 [Ollila et al, 2008], 15 [Wielders et al, 2011], 16 [Ollila et al, 2008], 17 [Guerrette et al, 1998], 18 [Yang et al, 2004]. d MAPP-MMR [Chao et al, 2008] All MSH2 and MSH6 VUS proteins were generated by the twostage PCR procedure, followed by their expression in vitro.…”

Section: Mmr Activities Of Msh2 and Msh6 Vusmentioning

confidence: 99%

A rapid and cell-free assay to test the activity of lynch syndrome-associated MSH2 and MSH6 missense variants

et al. 2011

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Lynch syndrome (LS) is an autosomal dominant disorder that predisposes to colon, endometrial, and other cancers. LS is caused by a heterozygous germline mutation in one of the DNA mismatch repair (MMR) genes. A significant proportion of all mutations found in suspected LS patients comprises single amino acid alterations. The pathogenicity of these variants of uncertain significance (VUS) is difficult to assess, precluding diagnosis of carriers and their relatives. Here we present a rapid cell-free assay to investigate MMR activity of MSH2 or MSH6 VUS. We used this assay to analyze a series of MSH2 and MSH6 VUS, selected from the Leiden Open Variation Database. Whereas a significant fraction of the MSH2 VUS has lost MMR activity, suggesting pathogenicity, the large majority of the MSH6 VUS appears MMR proficient. We anticipate that this assay will be an important tool in the development of a comprehensive and widely applicable diagnostic procedure for LS-associated VUS.

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“…We and other groups have addressed this challenge by studying the phenotypic consequences of nontruncating patient-derived MMR gene mutations in functional assays [Kariola et al, 2002[Kariola et al, , 2004Ollila et al, 2006b;Ou et al, 2007;Raevaara et al, 2005]. In our previous MSH2 studies, including 17 nontruncating MSH2 variants found in putative HNPCC patients [Ollila et al, 2006b[Ollila et al, , 2008, we showed that 12 of them impaired MMR. These could therefore be clearly classified as predisposing to HNPCC.…”

Section: Introductionmentioning

confidence: 96%

Mechanisms of pathogenicity in humanMSH2missense mutants

et al. 2008

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The human mismatch repair (MMR) gene MSH2 is the second most frequently mutated hereditary nonpolyposis colorectal cancer (HNPCC) susceptibility locus. Given that missense mutations account for 17% of all identified alterations in this gene, the study of their pathogenicity is of increasing importance. Previously, we showed that pathogenic MSH2 missense mutations typically impaired the repair activity of the protein. In this study, we took advantage of its crystal structure and attempted to correlate the mismatch binding and ATP-catalyzed mismatch release activities with the location of 18 nontruncating MSH2 mutations. We observed that the MMR-deficient mutations situated in the amino-terminal connector and lever domains of MSH2 (V161D, G162R, G164R, L173P, L187P, C333Y, and D603N) affected protein stability, whereas mutations in the ATPase domain (A636P, G674A, C697F, I745_I746del, and E749 K) mainly caused defects in mismatch binding or release. Of the MMR-proficient variants, four (T33P, A272 V, G322D, and V923E) showed slightly reduced mismatch binding and/or release efficiencies compared to wild-type (WT) protein, while two variants (N127S and A834 T) showed no defects in the assays. Similar to our biochemical data, the mutations that affected protein stability were associated with an absence of the protein in tumors in immunohistochemical (IHC) analyses. In contrast, the protein with the mutation E749 K, which abrogates MMR but not protein stability, is well expressed in tumors. In conclusion, pathogenic missense mutations in MSH2 may interfere with different mechanisms that tend to cluster in separate protein domains with varying effects on protein stability, which could be taken into account when interpreting IHC data.

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Uncertain pathogenicity of MSH2 variants N127S and G322D challenges their classification

Cited by 7 publications

References 37 publications

Mismatch repair analysis of inherited MSH2 and/or MSH6 variation pairs found in cancer patients

Mismatch repair analysis of inherited MSH2 and/or MSH6 variation pairs found in cancer patients

A rapid and cell-free assay to test the activity of lynch syndrome-associated MSH2 and MSH6 missense variants

Mechanisms of pathogenicity in humanMSH2missense mutants

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