This research article describes a case series investigating three families with suspected Lynch syndrome. The study used genetic screening via whole-exome sequencing and immunohistochemical analysis to characterize pathogenic variants in the MSH2 gene, with no comparator group reported. The population consisted of three families, though the clinical setting was not specified.
In Family 1, researchers identified the missense variant NM_000251.3:c.2633A>T:p.E878V, which was classified as a variant of uncertain significance. Family 2 had the missense variant NM_000251.3:c.998G>A:p.C333Y, confirmed as pathogenic. Family 3 showed a novel frameshift deletion, NM_000251.3:c.507del:p.Q170Rfs*4, identified as a pathogenic variant. No effect sizes, absolute numbers, p-values, or confidence intervals were reported for these findings.
Safety and tolerability data were not reported. The study has several important limitations: it included only three families, providing a very small sample size; it was an observational case series design without statistical testing; and it reported no clinical outcome data for affected individuals. The authors note this provides experimental evidence for precision screening and genetic counseling, but causation was not established.
For clinical practice, these findings should be interpreted with caution. The identification of specific MSH2 variants, including one novel pathogenic variant, in suspected Lynch syndrome families adds to the genetic characterization of this condition. However, the extremely limited sample size and lack of clinical correlation mean these results are preliminary. Clinicians should await confirmation from larger, more robust studies before applying these specific genetic findings to counseling or management decisions.
Researchers looked at three families with a history of colon cancer who doctors thought might have Lynch syndrome, a genetic condition that increases cancer risk. They used genetic testing to search for changes in the MSH2 gene, which is often involved in Lynch syndrome. The study found a different genetic variant in each family. In two families, the variants were confirmed to be disease-causing. In the third family, the variant's effect was unclear and labeled as 'uncertain significance.' The researchers also found one brand new genetic change that had not been seen before, which they classified as disease-causing. This was a very small study of only three families, which means the findings cannot be applied to most people. It was an observational case series, which is an early form of research that describes findings but doesn't prove cause and effect. The study did not report any safety concerns from the genetic testing itself. The main reason to be careful is that this research doesn't tell us anything about whether finding these variants changes a person's actual cancer risk or health outcomes. It also doesn't provide guidance on what to do if a variant of uncertain significance is found. Readers should understand this as a preliminary genetic analysis that helps scientists understand the variety of changes that can occur in the MSH2 gene. It provides evidence for the importance of precise genetic screening and counseling, but it is not yet practice-changing for patients.
What this means for you: Early genetic study in three families identifies Lynch syndrome variants; findings are preliminary and not yet useful for most patients.
View Original Abstract ↓
ObjectiveThis study aimed to characterize the pathogenic variants in three colon cancer families suspected of Lynch syndrome (LS), providing experimental evidence for precision screening and genetic counseling of the disease.MethodsThree suspected LS families were first identified, and subsequently, immunohistochemical analysis was performed on colon tissue samples from probands to assess the expression of four DNA mismatch repair proteins. Whole-exome sequencing was conducted to screen for potential pathogenic variants within the families. The SWISS-MODEL online platform was used to predict the three-dimensional structures of the mutant and wild-type proteins based on bioinformatics analysis. The predicted structures were then visualized using PyMOL software.ResultsTwo known MSH2 missense variants were identified: NM_000251.3:c.2633A>T:p.E878V in Family 1 and NM_000251.3:c.998G>A:p.C333Y in Family 2. A novel variant, designated as NM_000251.3:c.507del:p.Q170Rfs*4, was identified in the MSH2 gene of Family 3. This variant is caused by the deletion of an adenine at nucleotide position 507 within the MSH2 coding sequence, resulting in a frameshift. Consequently, glutamine at amino acid position 170 is altered to arginine, and a premature termination codon is introduced three residues downstream. This frameshift is predicted to generate a truncated protein of only 172 amino acids.ConclusionThe MSH2 missense variant NM_000251.3:c.2633A>T:p.E878V was classified as a variant of uncertain significance regarding its role in LS. In contrast, the NM_000251.3:c.998G>A:p.C333Y missense variant was confirmed as pathogenic. Furthermore, the novel frameshift deletion NM_000251.3:c.507del:p.Q170Rfs*4 was also identified as a pathogenic variant.
