Clinical utility gene card for: Lynch syndrome (MLH1, MSH2, MSH6, PMS2)

A Rare MSH2 Variant as a Candidate Marker for Lynch Syndrome II Screening in Tunisia: A Case of Diffuse Gastric Carcinoma

Several syndromic forms of digestive cancers are known to predispose to early-onset gastric tumors such as Hereditary Diffuse Gastric Cancer (HDGC) and Lynch Syndrome (LS). LSII is an extracolonic cancer syndrome characterized by a tumor spectrum including gastric cancer (GC). In the current work, our main aim was to identify the mutational spectrum underlying the genetic predisposition to diffuse gastric tumors occurring in a Tunisian family suspected of both HDGC and LS II syndromes. We selected the index case “JI-021”, which was a woman diagnosed with a Diffuse Gastric Carcinoma and fulfilling the international guidelines for both HDGC and LSII syndromes. For DNA repair, a custom panel targeting 87 candidate genes recovering the four DNA repair pathways was used. Structural bioinformatics analysis was conducted to predict the effect of the revealed variants on the functional properties of the proteins. DNA repair genes panel screening identified two variants: a rare MSH2 c.728G>A classified as a variant with uncertain significance (VUS) and a novel FANCD2 variant c.1879G>T. The structural prediction model of the MSH2 variant and electrostatic potential calculation showed for the first time that MSH2 c.728G>A is likely pathogenic and is involved in the MSH2-MLH1 complex stability. It appears to affect the MSH2-MLH1 complex as well as DNA-complex stability. The c.1879G>T FANCD2 variant was predicted to destabilize the protein structure. Our results showed that the MSH2 p.R243Q variant is likely pathogenic and is involved in the MSH2-MLH1 complex stability, and molecular modeling analysis highlights a putative impact on the binding with MLH1 by disrupting the electrostatic potential, suggesting the revision of its status from VUS to likely pathogenic. This variant seems to be a shared variant in the Mediterranean region. These findings emphasize the importance of testing DNA repair genes for patients diagnosed with diffuse GC with suspicion of LSII and colorectal cancer allowing better clinical surveillance for more personalized medicine.

Unique Combination of Diamond-Blackfan Anemia and Lynch Syndrome in Adult Female: A Case Report

We present an extremely rare clinical case of a 38-year-old Russian patient with multiple malignant neoplasms of the uterus and colon caused by genetically confirmed two hereditary diseases: Diamond-Blackfan anemia and Lynch syndrome. Molecular genetic research carried out by various methods (NGS, Sanger sequencing, aCGH, and MLPA) revealed a pathogenic nonsense variant in the MSH6 gene: NM_000179.2: c.742C>T, p.(Arg248Ter), as well as a new deletion of the chromosome 15's locus with the capture of 82,662,932-84,816,747 bp interval, including the complete sequence of the RPS17 gene. The lack of expediency of studying microsatellite instability in endometrial tumors using standard mononucleotide markers NR21, NR24, NR27, BAT25, BAT26 was demonstrated. The estimated prevalence of patients with combination of Diamond-Blackfan anemia and Lynch syndrome in the world is one per 480 million people.

Psychiatric implications of cancer genetic testing

As genetic testing for hereditary cancer syndromes has transitioned from research to clinical settings, research regarding its accompanying psychosocial effects has grown. Men and women being tested for hereditary cancer syndromes may experience some psychological distress while going through the process of testing or after carrier status is identified. Psychological distress appears to decrease over the course of the first year and it is typically not clinically significant. Longer term studies show mixed results with some mutation carriers continuing to experience elevated distress. Baseline distress is the greatest risk factor for both immediate (weeks-12 months) and long-term psychological distress (18 mo-8 years post genetic testing). In addition to baseline psychological distress, other risk factors can be identified to help identify individuals who may need psychosocial interventions during the genetic testing process. The challenges of providing clinical care to the growing population of individuals identified to be at increased risk for heritable cancers present opportunities for research and new models of care.

Patient compliance based on genetic medicine: a literature review

For this literature review, medical literature data bases were searched for studies on patient compliance after genetic risk assessment. The review focused on conditions where secondary or tertiary preventive options exist, namely cancer syndromes (BRCA-related cancer, HNPCC/colon cancer), hemochromatosis, thrombophilia, smoking cessation, and obesity. As a counterpart, patient compliance was assessed regarding medication adherence and medical advice in some of the most epidemiologically important conditions (including high blood pressure, metabolic syndrome, and coronary heart disease) after receiving medical advice based on nongenetic risk information or a combination of genetic and nongenetic risk information. In the majority of studies based on genetic risk assessments, patients were confronted with predictive rather than diagnostic genetic profiles. Most of the studies started from a knowledge base around 10 years ago when DNA testing was at an early stage, limited in scope and specificity, and costly. The major result is that overall compliance of patients after receiving a high-risk estimate from genetic testing for a given condition is high. However, significant behavior change does not take place just because the analyte is "genetic." Many more factors play a role in the complex process of behavioral tuning. Without adequate counseling and guidance, patients may interpret risk estimates of predictive genetic testing with an increase in fear and anxiety.

The challenge of implementing genetic tests with clinical utility while avoiding unsound applications

Genetics and genomics have developed fast in the last decade, but have not revolutionized medicine, as some had expected. While translation of research findings to public health applications is lagging behind, direct-to-consumer (DTC) offers of genetic testing have become available, both for monogenic and severe genetic disorders and for genetic variants possibly associated with common complex diseases (susceptibility variants). The European Society of Human Genetics is concerned about the way in which commercial companies are currently introducing genetic tests into the market outside of the scope of the traditional health-care system. There is a sort of a paradox between the lagging implementation in health care of the few genetic tests with proven clinical utility, on the one hand, and the speedy DTC offer of tests, with or without clinical utility. To translate research findings into appropriate clinical applications, assessment of the clinical validity and utility is needed. Many of the parameters needed in assessment frameworks are not available yet. Clinically relevant associations between genetic variants and disease risks have been established, e.g., in oncogenetics and cardiogenetics, and can be used to reflect on the possibilities and obstacles in using the new genetics in public health. In the absence of sufficient information on clinical validity and clinical utility, introduction of genetic tests in common complex disorders is often premature. Priority should be given to settings where clinical utility is proven or likely, to gain additional information concerning diagnosis, prognosis, and disease management. Monitoring and evaluation are essential.