P18: Molecular analysis of unclassified variants in MLH1 and MSH2 genes

Francesca Duraturo1, Raffaella Liccardo1, Giovanni Battista Rossi2, Marina De Rosa1, Paola Izzo1.

1 – Dep Molecular Medicine and Medical Biotecnology, University of Naples, “Federico II”, Italy. 2 – Endoscopy Unit Research and Care Institute “Pascale” Napoli, Italy

Aim

In this study, we have tested two unclassified variants (UVs) detected in the 3’untranslated regions (3’UTR) of the MLH1 and MSH2 genes (c*30_32delTTC in the MLH1 gene and c*226A>G in the MSH2 gene).

Method

The multivariate analysis of this variants by in silico analysis, quantification of mRNA and protein level and functional luciferase assay was performed in order to assess the correlation with the disease phenotype.

Results

For UV in MSH2, this multivariate analysis showed increased mRNA and protein levels, as also confirmed by a functional luciferase assay. In silico analysis was performed for prediction of miRNA target sites (TargetScan and MiRanda) and transcriptional regulation factor binding sites (TRANSFAC). The region in which falls the mutation is identified as a putative target point of two miRNAs (hsa-miR-137, hsa-miR47953p), and some trans-acting protein factors, known also as transcriptional repressors.

Conclusion

Therefore, we hypothesized that this variant could prevent the binding of these factors with the MSH2 3’UTR leading to unregulated expression of the MSH2 gene. In agreement with several literature data showing a deleterious effect derived from overproduction of MMR proteins3, it is conceivable that the variant c.*226A> G in the MSH2 gene has a pathogenic role in the development of the disease.

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