Challenging interpretation of germline TP53 variants based on the experience of a national comprehensive cancer centre.

TP53 variant interpretation is still challenging, especially in patients with attenuated Li-Fraumeni syndrome (LFS). We investigated the prevalence of pathogenic/likely pathogenic (P/LP) variants and LFS disease in the Hungarian population of cancer patients. By testing 893 patients with multiplex or familial cancer, we identified and functionally characterized novel splice variants of TP53 helping accurate variant classification. The differences among various semi-automated interpretation platforms without manual curation highlight the importance of focused interpretation as the automatic classification systems do not apply the TP53-specific criteria. The predicted frequency of the TP53 P/LP variants in Hungary is 0.3 per million which most likely underestimates the real prevalence. The higher detection rate of disease-causing variants in patients with attenuated LFS phenotype compared to the control population (OR 12.5; p < 0.0001) may raise the potential benefit of the TP53 genetic testing as part of the hereditary cancer panels of patients with multiple or familial cancer even when they do not meet Chompret criteria. Tumours developed at an earlier age in phenotypic LFS patients compared to the attenuated LFS patients which complicates genetic counselling as currently there are no different recommendations in surveillance protocols for LFS, phenotypic LFS, and attenuated LFS patients.

On the asymmetry of the residue compositions of the binding sites on protein surfaces.

By screening all the ligand binding sites in the Protein Data Bank, we have found that while it is geometrically possible that a loop, formed from a protein chain with residues ZYX, would "impersonate" another chain-loop with residues XYZ by a simple twisting of either the loop or the bound ligand, it almost never happens. This fact is rather surprising, and implies a notable asymmetry, since (i) loops in the folded proteins sometimes can be flexible enough to be twisted, but (ii) ligands are almost always extremely mobile before binding to the protein, therefore they can turn around and bind to residue-sequence ZYX as well. Data availability: The supplementary Table 3 lists the appearances of the residue-sequences and their inverses in the binding sites of the whole PDB, and is available at http://www.worldscient.com/jbcb/.