Diagnostic uncertainties, ethical tensions, and accounts of role responsibilities in genetic counseling communication.

Diagnostic uncertainties are intricately associated with genomic testing-especially concerning new technologies such as exome sequencing-with test results being either inconclusive or generating secondary findings or showing variants of uncertain significance. In the process of genetic counseling, diagnostic uncertainties have to be managed even when test results for an individual client are either positive or negative because of differential implications for family members. Previous studies have investigated diagnostic uncertainties in relation to clients wanting to know or not know the test results; here, we extend this line of research by addressing how genetic counselors and clients account for the management of diagnostic uncertainties vis-à-vis the attendant ethical tensions in the complex communicative environment in the clinic setting. Our dataset from the Norwegian context is longitudinal, consisting of ten audio-recorded pre-test genetic counseling sessions. It involves one extended family with a high burden of colorectal cancer. Through theme-oriented discourse analysis, we demonstrate how diagnostic uncertainties give rise to tensions concerning risks and benefits of knowing in both professional and familial spheres, which then map onto accounts of various role responsibilities. For instance, in looking for certainty via advanced genomic testing to reduce diagnostic uncertainty for clients, genetic counselors are confronted with tensions regarding what can be communicated and made known because of their role responsibilities toward what may be regarded as scientific others and clinical others. Likewise, clients are faced with tensions concerning wanting to know/not know, which invokes various familial others and may align or not align with genetic counselors' preferences, especially relating to management of diagnostic uncertainties and secondary findings.

Role of germline aberrations affecting CTNNA1, MAP3K6 and MYD88 in gastric cancer susceptibility.

BACKGROUND: In approximately 10% of all gastric cancer (GC) cases, a heritable cause is suspected. A subset of these cases have a causative germline CDH1 mutation; however, in most cases the cause remains unknown. Our objective was to assess to what extent these remaining cases may be explained by germline mutations in the novel candidate GC predisposing genes CTNNA1, MAP3K6 or MYD88. METHODS: We sequenced a large cohort of unexplained young and/or familial patients with GC (n=286) without a CDH1germline mutation for germline variants affecting CTNNA1, MAP3K6 and MYD88 using a targeted next-generation sequencing approach based on single-molecule molecular inversion probes. RESULTS: Predicted deleterious germline variants were not encountered in MYD88, but recurrently observed in CTNNA1 (n=2) and MAP3K6 (n=3) in our cohort of patients with GC. In contrast to deleterious variants in CTNNA1, deleterious variants in MAP3K6 also occur frequently in the general population. CONCLUSIONS: Based on our results MAP3K6 should no longer be considered a GC predisposition gene, whereas deleterious CTNNA1 variants are confirmed as an infrequent cause of GC susceptibility. Biallelic MYD88 germline mutations are at most a very rare cause of GC susceptibility as no additional cases were identified.

Unraveling genetic predisposition to familial or early onset gastric cancer using germline whole-exome sequencing.

Recognition of individuals with a genetic predisposition to gastric cancer (GC) enables preventive measures. However, the underlying cause of genetic susceptibility to gastric cancer remains largely unexplained. We performed germline whole-exome sequencing on leukocyte DNA of 54 patients from 53 families with genetically unexplained diffuse-type and intestinal-type GC to identify novel GC-predisposing candidate genes. As young age at diagnosis and familial clustering are hallmarks of genetic tumor susceptibility, we selected patients that were diagnosed below the age of 35, patients from families with two cases of GC at or below age 60 and patients from families with three GC cases at or below age 70. All included individuals were tested negative for germline CDH1 mutations before or during the study. Variants that were possibly deleterious according to in silico predictions were filtered using several independent approaches that were based on gene function and gene mutation burden in controls. Despite a rigorous search, no obvious candidate GC predisposition genes were identified. This negative result stresses the importance of future research studies in large, homogeneous cohorts.

The perceived impact of the European registration system for genetic counsellors and nurses.

The aim of the European Board of Medical Genetics has been to develop and promote academic and professional standards necessary in order to provide competent genetic counselling services. The aim of this study was to explore the impact of the European registration system for genetic nurses and counsellors from the perspectives of those professionals who have registered. Registration system was launched in 2013. A cross-sectional, online survey was used to explore the motivations and experiences of those applying for, and the effect of registration on their career. Fifty-five Genetic Nurses and Counsellors are registered till now, from them, thirty-three agreed to participate on this study. The main motivations for registering were for recognition of their work value and competence (30.3%); due to the absence of a registration system in their own country (15.2%) and the possibility of obtaining a European/international certification (27.3%), while 27.3% of respondents registered to support recognition of the genetic counselling profession. Some participants valued the registration process as an educational activity in its own right, while the majority indicated the greatest impact of the registration process was on their clinical practice. The results confirm that registrants value the opportunity to both confirm their own competence and advance the genetic counselling profession in Europe.

Use of multigene-panel identifies pathogenic variants in several CRC-predisposing genes in patients previously tested for Lynch Syndrome.

BACKGROUND: Many families with a high burden of colorectal cancer fulfil the clinical criteria for Lynch Syndrome. However, in about half of these families, no germline mutation in the mismatch repair genes known to be associated with this disease can be identified. The aim of this study was to find the genetic cause for the increased colorectal cancer risk in these unsolved cases. MATERIALS AND METHODS: To reach the aim, we designed a gene panel targeting 112 previously known or candidate colorectal cancer susceptibility genes to screen 274 patient samples for mutations. Mutations were validated by Sanger sequencing and, where possible, segregation analysis was performed. RESULTS: We identified 73 interesting variants, of whom 17 were pathogenic and 19 were variants of unknown clinical significance in well-established cancer susceptibility genes. In addition, 37 potentially pathogenic variants in candidate colorectal cancer susceptibility genes were detected. CONCLUSION: In conclusion, we found a promising DNA variant in more than 25 % of the patients, which shows that gene panel testing is a more effective method to identify germline variants in CRC patients compared to a single gene approach.

A novel POLE mutation associated with cancers of colon, pancreas, ovaries and small intestine.

In some families there is an increased risk for colorectal cancer, caused by heritable, but often unidentified genetic mutations predisposing to the disease. We have identified the likely genetic cause for disease predisposition in a large family with high burden of colorectal adenomas and carcinomas, in addition to extra-colonic cancers. This family had previously been tested for known cancer susceptibility genes, with negative results. Exome sequencing was used to identify a novel mutation, c.1373A>T (p.Tyr458Phe), in the gene for DNA polymerase epsilon catalytic subunit (POLE). This mutation is located in the active site of the exonuclease domain of the enzyme, and affects a residue that has previously been shown to be important for exonuclease activity. The first predisposing mutation identified in POLE (c.1270C>G, p.Leu424Val) was associated with colorectal cancer only, but another mutation with a broader tumour spectrum (c.1089C>A, p.Asn363Lys) has recently been reported. In the family described in the present study, carriers generally have multiple colorectal adenomas and cancer of colon, pancreas, ovaries and small intestine which represents an important broadening of the tumour spectrum of POLE mutation carriers. We also observe a large phenotypic variation among the POLE mutation carriers in this family, most likely explained by modifying variants in other genes. One POLE mutation carrier has a novel variant in EXO1 (c.458C>T, p.Ala153Val), which may contribute to a more severe phenotype. The findings in this study will have important implications for risk assessment and surveillance of POLE mutation carriers.

The Norwegian PMS2 founder mutation c.989-1G > T shows high penetrance of microsatellite instable cancers with normal immunohistochemistry.

BACKGROUND: Using immunohistochemistry (IHC) to select cases for mismatch repair (MMR) genetic testing, we failed to identify a large kindred with the deleterious PMS2 mutation c.989-1G > T. The purpose of the study was to examine the sensitivity of IHC and microsatellite instability-analysis (MSI) to identify carriers of the mutation, and to estimate its penetrance and expressions. METHODS: All carriers and obligate carriers of the mutation were identified. All cancer diagnoses were confirmed. IHC and MSI-analysis were performed on available tumours. Penetrances of cancers included in the Amsterdam and the Bethesda Criteria, for MSI-high tumours and MSI-high and low tumours were calculated by the Kaplan-Meier algorithm. RESULTS: Probability for co-segregation of the mutation and cancers by chance was 0.000004. Fifty-six carriers or obligate carriers were identified. There was normal staining for PMS2 in 15/18 (83.3%) of tumours included in the AMS1/AMS2/Bethesda criteria. MSI-analysis showed that 15/21 (71.4%) of tumours were MSI-high and 4/21 (19.0%) were MSI-low. Penetrance at 70 years was 30.6% for AMS1 cancers (colorectal cancers), 42.8% for AMS2 cancers, 47.2% for Bethesda cancers, 55.6% for MSI-high and MSI-low cancers and 52.2% for MSI-high cancers. CONCLUSIONS: The mutation met class 5 criteria for pathogenicity. IHC was insensitive in detecting tumours caused by the mutation. Penetrance of cancers that displayed MSI was 56% at 70 years. Besides colorectal cancers, the most frequent expressions were carcinoma of the endometrium and breast in females and stomach and prostate in males.

Current clinical criteria for Lynch syndrome are not sensitive enough to identify MSH6 mutation carriers.

BACKGROUND: Reported prevalence, penetrance and expression of deleterious mutations in the mismatch repair (MMR) genes, MLH1, MSH2, MSH6 and PMS2, may reflect differences in the clinical criteria used to select families for DNA testing. The authors have previously reported that clinical criteria are not sensitive enough to identify MMR mutation carriers among incident colorectal cancer cases. OBJECTIVE: To describe the sensitivity of the criteria when applied to families with a demonstrated MMR mutation. METHODS: Families with an aggregation of colorectal cancers were examined for deleterious MMR mutations according to the Mallorca guidelines. All families with a detected MMR mutation as of November 2009 were reclassified according to the Amsterdam and Bethesda criteria. RESULTS: Sixty-nine different DNA variants were identified in a total of 129 families. The original Amsterdam clinical criteria were met by 38%, 12%, 78% and 25% of families with mutations in MSH2, MSH6, MLH1 and PMS2, respectively. Corresponding numbers for the revised Amsterdam criteria were 62%, 48%, 87% and 38%. Similarly, each of the four clinical Bethesda criteria had low sensitivity for identifying MSH6 or PMS2 mutations. CONCLUSION: Amsterdam criteria and each of the Bethesda criteria were inadequate for identifying MSH6 mutation-carrying kindreds. MSH6 mutations may be more common than currently assumed, and the penetrance/expression of MSH6 mutations, as derived from families meeting current clinical criteria, may be misleading. To increase detection rate of MMR mutation carriers, all cancers in the Lynch syndrome tumour spectrum should be subjected to immunohistochemical analysis and/or analysis for microsatellite instability.

A homozygote splice site PMS2 mutation as cause of Turcot syndrome gives rise to two different abnormal transcripts.

Turcot syndrome is a rare, inherited disease predisposing of tumours in the central nerve system and in the colorectal system. This report describes a Turcot patient with an extraordinary clinical history. The patient is still alive at the age of 43. She was operated at the age of 10 by brain tumour and at the age of 16 by colorectal cancer. She has since then been treated for multiple cancers (gastrointestinal, endometrial, basal cell carcinomas), and removal of adenomatous polyps at several occasions. The aim of this work was to investigate if there was any specific genotype that explains her remarkable clinical history. Microsatellite instability and immunohistochemistry analysis for four DNA mismatch repair proteins were performed. DNA mutation analysis was done for genes involved in polyposis and mismatch repair by denaturing high performance liquid chromatography and sequencing. cDNA analysis was carried out for the mismatch repair gene PMS2. The patients genotype was found to be a homozygous splice site mutation in the PMS2 gene, c.989-1G