Head-and-neck paragangliomas are associated with sleep-related complaints, especially in the presence of carotid body tumors.

OBJECTIVES: The carotid body functions as a chemoreceptor. We hypothesized that head-and-neck paragangliomas (HNP) may disturb the function of these peripheral chemoreceptors and play a role in sleep-disordered breathing. DESIGN: This is a case-control study. SETTING: This study was conducted in a tertiary referral center. PARTICIPANTS AND MAIN OUTCOME MEASURES: We assessed fatigue, sleep, and exercise capacity in 74 HNP patients using three questionnaires (Epworth Sleepiness Scale, St. George Respiratory Questionnaire, and a standard clinical sleep assessment questionnaire). Outcomes were compared to those of age- and sex-matched controls. RESULTS AND CONCLUSIONS: Activity, disturbance of psychosocial function, and total score were worse compared to controls (15.4 ± 18.5 vs. 7.2 ± 9.9, P = 0.007; 5.3 ± 10.5 vs. 1.2 ± 2.6, P = 0.008; and 10.4 ± 12.9 vs. 5.0 ± 4.8, P = 0.006, respectively). Patients reported more daytime fatigue, concentration difficulties, and depression (51% vs. 24%, P = 0.006; 31% vs. 10%, P = 0.010; and 19% vs. 2%, P = 0.012). Waking up was reported to be less refreshing in HNP patients (53% vs. 73%, P = 0.038). Dysphonia was a predictor of symptoms, activity, disturbance of psychosocial function, and total scores. Remarkably, the presence of a carotid body tumor was an independent predictor of increased daytime sleepiness (ß = 0.287, P = 0.029). In conclusion, patients with HNP have remarkable sleep-related complaints. Especially the presence of carotid body tumors appears to be associated with increased daytime somnolence.

SDHAF2 mutations in familial and sporadic paraganglioma and phaeochromocytoma.

BACKGROUND: Paragangliomas and phaeochromocytomas are neuroendocrine tumours associated frequently with germline mutations of SDHD, SDHC, and SDHB. Previous studies have shown the imprinted SDHAF2 gene to be mutated in a large Dutch kindred with paragangliomas. We aimed to identify SDHAF2 mutation carriers, assess the clinical genetic significance of SDHAF2, and describe the associated clinical phenotype. METHODS: We undertook a multicentre study in Spain and The Netherlands in 443 apparently sporadic patients with paragangliomas and phaeochromocytomas who did not have mutations in SDHD, SDHC, or SDHB. We analysed DNA of 315 patients for germline mutations of SDHAF2; a subset (n=200) was investigated for gross gene deletions. DNA from a group of 128 tumours was studied for somatic mutations. We also examined a Spanish family with head and neck paragangliomas with a young age of onset for the presence of SDHAF2 mutations, undertook haplotype analysis in this kindred, and assessed their clinical phenotype. FINDINGS: We did not identify any germline or somatic mutations of SDHAF2, and no gross gene deletions were noted in the subset of apparently sporadic patients analysed. Investigation of the Spanish family identified a pathogenic germline DNA mutation of SDHAF2, 232G-->A (Gly78Arg), identical to the Dutch kindred. INTERPRETATION: SDHAF2 mutations do not have an important role in phaeochromocytoma and are rare in head and neck paraganglioma. Identification of a second family with the Gly78Arg mutation suggests that this is a crucial residue for the function of SDHAF2. We conclude that SDHAF2 mutation analysis is justified in very young patients with isolated head and neck paraganglioma without mutations in SDHD, SDHC, or SDHB, and in individuals with familial antecedents who are negative for mutations in all other risk genes. FUNDING: Dutch Cancer Society, European Union 6th Framework Program, Fondo Investigaciones Sanitarias, Fundación Mutua Madrileña, and Red Temática de Investigación Cooperativa en Cáncer.

Quantification of sequence exchange events between PMS2 and PMS2CL provides a basis for improved mutation scanning of Lynch syndrome patients.

Heterozygous mutations in PMS2 are involved in Lynch syndrome, whereas biallelic mutations are found in Constitutional mismatch repair-deficiency syndrome patients. Mutation detection is complicated by the occurrence of sequence exchange events between the duplicated regions of PMS2 and PMS2CL. We investigated the frequency of such events with a nonspecific polymerase chain reaction (PCR) strategy, co-amplifying both PMS2 and PMS2CL sequences. This allowed us to score ratios between gene and pseudogene-specific nucleotides at 29 PSV sites from exon 11 to the end of the gene. We found sequence transfer at all investigated PSVs from intron 12 to the 3' end of the gene in 4 to 52% of DNA samples. Overall, sequence exchange between PMS2 and PMS2CL was observed in 69% (83/120) of individuals. We demonstrate that mutation scanning with PMS2-specific PCR primers and MLPA probes, designed on PSVs, in the 3' duplicated region is unreliable, and present an RNA-based mutation detection strategy to improve reliability. Using this strategy, we found 19 different putative pathogenic PMS2 mutations. Four of these (21%) are lying in the region with frequent sequence transfer and are missed or called incorrectly as homozygous with several PSV-based mutation detection methods.

Low penetrance of a SDHB mutation in a large Dutch paraganglioma family.

BACKGROUND: Germline mutations of the succinate dehydrogenase subunit B gene (SDHB) predispose carriers for paragangliomas, and current estimates of the chance of mutation carriers actually developing tumors (penetrance) are high. We evaluate the phenotype and penetrance of a germline SDHB mutation in a large and clinically well-characterized paraganglioma family. METHODS: Following identification of the mutation in a 31 year old index-patient, extensive clinical screening was performed in mutation carriers to evaluate the presence of head and neck, thoracic and abdominal paragangliomas. Presymptomatic DNA testing was performed in 19 family members. RESULTS: DNA analysis detected 14 further SDHB mutation carriers. Three mutation carriers (median age 78 years) declined clinical surveillance, but had no clinical signs or symptoms associated with paragangliomas. The remaining 11 mutation carriers (mean age 53, range 37-76 years) consented to clinical screening. In only two, aged 43 and 48 years, were subclinical vagal paragangliomas identified. CONCLUSIONS: Only three of the fifteen mutation carriers in this family have developed paraganglioma, which results in a calculated penetrance of 26% at 48 years of age. This figure is lower than current estimates, and we conclude that the co-operation of this family allowed an almost complete attainment of mutation carriers, and the extensive clinical evaluation carried out allowed us to identify all affected individuals.

Psychological distress and use of psychosocial support in familial adenomatous polyposis.

OBJECTIVE: Familial adenomatous polyposis (FAP) is characterized by multiple adenomas in the colorectum with a high risk to develop colorectal cancer. It is unclear whether individuals at risk of FAP experience distress due to this potentially life-threatening disease. This nationwide study assessed: (1) the prevalence of psychological distress; and (2) the need for and use of specialized professional psychosocial support. METHODS: In this cross-sectional study, all individuals from families at high risk for FAP registered at the Netherlands Foundation for the Detection of Hereditary Tumours were invited to complete a questionnaire assessing, among other issues, generalized, cancer-specific and FAP-specific distress. RESULTS: In total, 525 individuals completed the questionnaire. Approximately 20% of the respondents had moderate to severe levels of FAP-specific distress. Levels of generalized distress were comparable to the general Dutch population. Significantly more individuals with a FAP diagnosis had frequent cancer worries than those at risk of FAP or non-carriers (p=0.02). Distress levels were more strongly associated with psychosocial variables (e.g. perceived cancer risk), than with sociodemographic or clinical variables. Up to 43% of the variance in distress could be explained by all variables combined. Of those moderately to severely distressed, 26% had received specialized professional psychosocial support, while 30% of those did not receive the support they wanted. CONCLUSIONS: A substantial minority of individuals reported moderate to severe distress levels associated with FAP. However, only one-third of those received specialized professional psychosocial support. We recommend the use of a screening questionnaire to identify individuals in need of such support.

Prognostic factors for hereditary cancer distress six months after BRCA1/2 or HNPCC genetic susceptibility testing.

This study explored predictors for hereditary cancer distress six months after genetic susceptibility testing for a known familial BRCA1/2 or HNPCC related mutation, in order to gain insight into aspects relevant for the identification of individuals needing additional psychosocial support. Coping, illness representations, experiences with cancer in relatives and family system characteristics were assessed in 271 applicants for genetic testing before result disclosure. Hereditary cancer distress was assessed prospectively up to six months after disclosure. Regression analysis revealed that the pretest level of distress, complicated grief, the number of affected first-degree relatives and strong emotional illness representations were factors that best explained hereditary cancer distress. Other significant predictors were illness coherence, passive coping, distraction seeking, being aged <13 years when a parent was affected by cancer and family communication. Individuals who may benefit from additional support may be identified before result disclosure using a short instrument assessing the relevant aspects.

Comparison of individuals opting for BRCA1/2 or HNPCC genetic susceptibility testing with regard to coping, illness perceptions, illness experiences, family system characteristics and hereditary cancer distress.

OBJECTIVE: To study differences between individuals opting for genetic cancer susceptibility testing of a known familial BRCA1/2 and HNPCC related germline mutation. METHODS: Coping, illness perceptions, experiences with cancer in relatives and family system characteristics were assessed in 271 applicants for genetic testing before test result disclosure. Hereditary cancer distress, worry and cancer risk perception were assessed before, 1 week after, and 6 months after disclosure. RESULTS: Individuals from BRCA1/2 and HNPCC mutation families did not differ with regard to the number of experiences with cancer in relatives, grief symptoms, the course of cancer distress, worry and risk perception through time and most illness perceptions, coping responses and family characteristics. Individuals from BRCA1/2 families perceived hereditary cancer as more serious. They reported more frequently a passive coping style, cancer worry and a less open communication with their partner and children. CONCLUSION: Besides subtle differences, psychological mechanisms may be mainly identical in individuals opting for BRCA1/2 and HNPCC susceptibility testing. PRACTICE IMPLICATIONS: Based on our findings, using a similar counseling approach for individuals opting for BRCA1/2 or HNPCC genetic susceptibility testing is justified. In this approach, attention should be directed more to individual aspects than to the type of disorder.

Microsatellite instability, immunohistochemistry, and additional PMS2 staining in suspected hereditary nonpolyposis colorectal cancer.

PURPOSE: Immunohistochemistry (IHC) and microsatellite instability (MSI) analysis can be used to identify patients with a possible DNA mismatch repair defect [hereditary nonpolyposis colorectal carcinoma (HNPCC)]. The Bethesda criteria have been proposed to select families for determination of MSI. The aims of this study were to assess the yield of MSI analysis in families suspected for HNPCC, to compare the results of immunohistochemical staining and MSI analysis, and to assess the additional value of PMS2 staining. EXPERIMENTAL DESIGN: Clinical data and tumors were collected from 725 individuals from 631 families with suspected HNPCC. MSI analysis was performed using eight markers including the 5 National Cancer Institute markers. Four immunohistochemical staining antibodies were used (MLH1, MSH2, MSH6 and PMS2). RESULTS: A MSI-H (tumors with instability for >30% of the markers) phenotype in colorectal cancers (CRCs) was observed in 21-49% of families that met the various Bethesda criteria. In families with three cases of CRC diagnosed at age > 50 years, families with a solitary case of CRC diagnosed between ages 45 and 50 years, and families with one CRC case and a first-degree relative with a HNPCC-related cancer, one diagnosed between ages 45 and 50 years (all Bethesda-negative families), the yield of MSI-H was 10-26%. Immunohistochemical staining confirmed the MSI results in 93% of the cases. With IHC, adding PMS2 staining led to the identification of an additional 23% of subjects with an hMLH1 germ-line mutation (35 carriers were tested). CONCLUSIONS: The Bethesda guidelines for MSI analysis should include families with three or more cases of CRC diagnosed at age > 50 years. The age at diagnosis of CRC in the original guidelines should be raised to 50 years. Routine IHC diagnostics for HNPCC should include PMS2 staining.

Genetic testing in Li-Fraumeni syndrome: uptake and psychosocial consequences.

PURPOSE: Li-Fraumeni syndrome (LFS) is a hereditary cancer syndrome, characterized by a high risk of developing cancer at various sites and ages. To date, limited clinical benefits of genetic testing for LFS have been demonstrated, and there are concerns about the potential adverse psychosocial impact of genetic testing for LFS. In this study, we evaluated the uptake of genetic testing and the psychosocial impact of undergoing or not undergoing a genetic test for LFS. PATIENTS AND METHODS: In total, 18 families with a p53 germline mutation in the Netherlands were identified. Eligible family members were invited to complete a self-report questionnaire assessing motives for undergoing or not undergoing genetic testing, LFS-related distress and worries, and health-related quality of life. RESULTS: Uptake of presymptomatic testing was 55% (65 of 119). Of the total group, 23% reported clinically relevant levels of LFS-related distress. Carriers were not significantly more distressed than noncarriers or than those with a 50% risk who did not undergo genetic testing. Those with a lack of social support were more prone to report clinically relevant levels of distress (odds ratio, 1.3; 95% CI, 1.0 to 1.5). CONCLUSION: Although preventive and treatment options for LFS are limited, more than half of the family members from known LFS families choose to undergo presymptomatic testing. An unfavorable genetic test result, in general, does not cause adverse psychological effects. Nonetheless, it is important to note that a substantial proportion of individuals, irrespective of their carrier status, exhibit clinically relevant levels of distress which warrant psychological support.

Risks of Lynch syndrome cancers for MSH6 mutation carriers.

BACKGROUND: Germline mutations in MSH6 account for 10%-20% of Lynch syndrome colorectal cancers caused by hereditary DNA mismatch repair gene mutations. Because there have been only a few studies of mutation carriers, their cancer risks are uncertain. METHODS: We identified 113 families of MSH6 mutation carriers from five countries that we ascertained through family cancer clinics and population-based cancer registries. Mutation status, sex, age, and histories of cancer, polypectomy, and hysterectomy were sought from 3104 of their relatives. Age-specific cumulative risks for carriers and hazard ratios (HRs) for cancer risks of carriers, compared with those of the general population of the same country, were estimated by use of a modified segregation analysis with appropriate conditioning depending on ascertainment. RESULTS: For MSH6 mutation carriers, the estimated cumulative risks to ages 70 and 80 years, respectively, were as follows: for colorectal cancer, 22% (95% confidence interval [CI] = 14% to 32%) and 44% (95% CI = 28% to 62%) for men and 10% (95% CI = 5% to 17%) and 20% (95% CI = 11% to 35%) for women; for endometrial cancer, 26% (95% CI = 18% to 36%) and 44% (95% CI = 30% to 58%); and for any cancer associated with Lynch syndrome, 24% (95% CI = 16% to 37%) and 47% (95% CI = 32% to 66%) for men and 40% (95% CI = 32% to 52%) and 65% (95% CI = 53% to 78%) for women. Compared with incidence for the general population, MSH6 mutation carriers had an eightfold increased incidence of colorectal cancer (HR = 7.6, 95% CI = 5.4 to 10.8), which was independent of sex and age. Women who were MSH6 mutation carriers had a 26-fold increased incidence of endometrial cancer (HR = 25.5, 95% CI = 16.8 to 38.7) and a sixfold increased incidence of other cancers associated with Lynch syndrome (HR = 6.0, 95% CI = 3.4 to 10.7). CONCLUSION: We have obtained precise and accurate estimates of both absolute and relative cancer risks for MSH6 mutation carriers.

Molecular characterization of novel germline deletions affecting SDHD and SDHC in pheochromocytoma and paraganglioma patients.

A major cause of paraganglioma and pheochromocytoma is germline mutation of the tumor suppressor genes SDHB, SDHC, and SDHD, encoding subunits of succinate dehydrogenase (SDH). While many SDH missense/nonsense mutations have been identified, few large deletions have been described. We performed multiplex ligation-dependent probe amplification deletion analysis in 126 point mutation-negative patients, and here we describe four novel deletions of SDHD and SDHC. Long-range PCR was used for the fine mapping of deletions. One patient had a 10 kb AluSg-AluSx-mediated deletion including SDHD exons 1 and 2, the entire TIMM8B gene, and deletion of exons of C11orf57. A second patient had a deletion of SDHD exons 1 and 2 and exon 1 of the TIMM8B gene. A third patient showed a deletion of exon 2 of SDHD, together with a 235 bp MIRb-Tensin gene insertion. In a fourth patient, a deletion of exons 5 and 6 of the SDHC gene was found, only the second SDHC deletion currently known. The deletions of the TIMM8B and C11orf57 genes are the first to be described, but do not appear to result in an additional phenotype in these patients. Four of the eight breakpoints occurred in Alu sequences and all three SDHD deletions showed an intron 2 breakpoint. This study underlines the fact that clinically relevant deletions may encompass neighboring genes, with the potential to modify phenotype. Gene deletions of SDHD and SDHC represent a substantial proportion of all mutations, and must be considered in paraganglioma patients shown to be negative for mutations by sequencing.

The common sense model of self-regulation and psychological adjustment to predictive genetic testing: a prospective study.

This prospective study explored the contribution of illness representations and coping to cancer-related distress in unaffected individuals undergoing predictive genetic testing for an identified mutation in BRCA1/2 (BReast CAncer) or an HNPCC (Hereditary Nonpolyposis Colorectal Cancer)-related gene, based on the common sense model of self-regulation. Coping with hereditary cancer (UCL), illness representations (IPQ-R) and risk perception were assessed in 235 unaffected applicants for genetic testing before test result disclosure. Hereditary cancer distress (IES) and cancer worry (CWS) were assessed before, 2 weeks after and 6 months after result disclosure. Timeline (r = 0.30), consequences (r = 0.25), illness coherence (r = 0.21) and risk perception (r = 0.20) were significantly correlated to passive coping. Passive coping predicted hereditary cancer distress and cancer worry from pre-test (beta = 0.46 and 0.42, respectively) up to 6 months after result disclosure (beta = 0.32 and 0.19, respectively). Illness coherence predicted hereditary cancer distress up to 6 months after result disclosure (beta = 0.24), too. The self-regulatory model may be useful to predict the cognitive and emotional reactions to genetic cancer susceptibility testing. Identifying unhelpful representations and cognitive restructuring may be appropriate interventions to help distressed individuals undergoing genetic susceptibility testing for a BRCA1/2 or a HNPCC-related mutation.

A prospective study of the impact of genetic susceptibility testing for BRCA1/2 or HNPCC on family relationships.

This study assessed the impact of genetic testing for cancer susceptibility on family relationships and determinants of adverse consequences for family relationships. Applicants for genetic testing of a known familial pathogenic mutation in BRCA1/2 or a HNPCC related gene (N=271) rated the prevalence and nature of changes in family relationships, familial difficulties and conflicts due to genetic testing 6 months after receiving the test result. The level of family functioning, differentiation from parents, support and familial communication style regarding hereditary cancer were assessed before receiving the test result. Genetic testing affected some family relationships in a positive way (37%), i.e. by feeling closer, improved communication and support, more appreciation of the relative and relief of negative test result. A minority reported unwanted changes in relationships (19%), problematic situations (13%) or conflicts (4%). Adverse effects comprised feelings of guilt towards children and carrier siblings, imposed secrecy and communication problems. Predictors of adverse consequences on family relationships were reluctance to communicate about hereditary cancer with relatives and disengaged-rigid or enmeshed-chaotic family functioning. Open communication between relatives should be stimulated because a lack of open communication may be an important determinant of familial adverse effects.

Diagnostic approach and management of Lynch syndrome (hereditary nonpolyposis colorectal carcinoma): a guide for clinicians.

ABSTRACT diagnostic workup of familial colorectal cancer is an elaborate and time consuming process in which the family and several medical specialists closely collaborate. However, establishing a diagnosis can be very rewarding. If a mutation is detected in the family, a satisfactory explanation can be provided for an accumulation of tumors at young age, and often of untimely death. Appropriate presymptomatic testing can be offered to reduce mortality among at-risk family members, and relatives not at risk can avoid uncertainty and needlessly intensive surveillance. We show the differential diagnostic considerations when an individual with a family history of colorectal carcinoma is encountered, with emphasis on Lynch syndrome (Hereditary Nonpolyposis Colorectal Carcinoma [HNPCC]). Practical recommendations for laboratory workup of suspected Lynch syndrome, including analysis of tumor tissue by microsatellite instability analysis and immunohistochemistry, and germline DNA analysis are given. Furthermore, the clinical management after a molecular diagnosis has been made is described. The diagnostic scheme presented here allows efficient and effective analysis of colorectal carcinoma cases with (suspected) Lynch syndrome, making optimal use of currently available technology.

Bleeding in carriers of hemophilia.

A wide range of factor VIII and IX levels is observed in heterozygous carriers of hemophilia as well as in noncarriers. In female carriers, extreme lyonization may lead to low clotting factor levels. We studied the effect of heterozygous hemophilia carriership on the occurrence of bleeding symptoms. A postal survey was performed among most of the women who were tested for carriership of hemophilia in the Netherlands before 2001. The questionnaire included items on personal characteristics, characteristics of hemophilia in the affected family members, and carrier testing and history of bleeding problems such as bleeding after tooth extraction, bleeding after tonsillectomy, and other operations. Information on clotting factor levels was obtained from the hospital charts. Logistic regression was used to assess the relation of carrier status and clotting factor levels with the occurrence of hemorrhagic events. In 2004, 766 questionnaires were sent, and 546 women responded (80%). Of these, 274 were carriers of hemophilia A or B. The median clotting factor level of carriers was 0.60 IU/mL (range, 0.05-2.19 IU/mL) compared with 1.02 IU/mL (range, 0.45-3.28 IU/mL) in noncarriers. Clotting factor levels from 0.60 to 0.05 IU/mL were increasingly associated with prolonged bleeding from small wounds and prolonged bleeding after tooth extraction, tonsillectomy, and operations. Carriers of hemophilia bleed more than other women, especially after medical interventions. Our findings suggest that not only clotting factor levels at the extreme of the distribution, resembling mild hemophilia, but also mildly reduced clotting factor levels between 0.41 and 0.60 IU/mL are associated with bleeding.

Heterozygous mutations in PMS2 cause hereditary nonpolyposis colorectal carcinoma (Lynch syndrome).

BACKGROUND & AIMS: The role of the mismatch repair gene PMS2 in hereditary nonpolyposis colorectal carcinoma (HNPCC) is not fully clarified. To date, only 7 different heterozygous truncating PMS2 mutations have been reported in HNPCC-suspected families. Our aim was to further assess the role of PMS2 in HNPCC. METHODS: We performed Southern blot analysis in 112 patients from MLH1-, MSH2-, and MSH6-negative HNPCC-like families. A subgroup (n = 38) of these patients was analyzed by denaturing gradient gel electrophoresis (DGGE). In a second study group consisting of 775 index patients with familial colorectal cancer, we performed immunohistochemistry using antibodies against MLH1, MSH2, MSH6, and PMS2 proteins. In 8 of 775 tumors, only loss of PMS2 expression was found. In these cases, we performed Southern blot analysis and DGGE. Segregation analysis was performed in the families with a (possibly) deleterious mutation. RESULTS: Seven novel mutations were identified: 4 genomic rearrangements and 3 truncating point mutations. Three of these 7 families fulfill the Amsterdam II criteria. The pattern of inheritance is autosomal dominant with a milder phenotype compared with families with pathogenic MLH1 or MSH2 mutations. Microsatellite instability and immunohistochemical analysis performed in HNPCC-related tumors from proven carriers showed a microsatellite instability high phenotype and loss of PMS2 protein expression in all tumors. CONCLUSIONS: We show that heterozygous truncating mutations in PMS2 do play a role in a small subset of HNPCC-like families. PMS2 mutation analysis is indicated in patients diagnosed with a colorectal tumor with absent staining for the PMS2 protein.

Cancer risk in hereditary nonpolyposis colorectal cancer due to MSH6 mutations: impact on counseling and surveillance.

BACKGROUND & AIMS: Hereditary nonpolyposis colorectal carcinoma (HNPCC) is caused by a mutated mismatch repair (MMR) gene. The aim of our study was to determine the cumulative risk of developing cancer in a large series of MSH6 mutation carriers. METHODS: Mutation analysis was performed in 20 families with a germline mutation in MSH6. We compared the cancer risks between MSH6 and MLH1/MSH2 mutation carriers. Microsatellite instability (MSI) analysis and immunohistochemistry (IHC) were performed in the available tumors. RESULTS: A total of 146 MSH6 mutation carriers were identified. In these carriers, the cumulative risk for colorectal carcinoma was 69% for men, 30% for women, and 71% for endometrial carcinoma at 70 years of age. The risk for all HNPCC-related tumors was significantly lower in MSH6 than in MLH1 or MSH2 mutation carriers (P = 0.002). In female MSH6 mutation carriers, the risk for colorectal cancer was significantly lower (P = 0.0049) and the risk for endometrial cancer significantly higher (P = 0.02) than in MLH1 and MSH2 mutation carriers. In male carriers, the risk for colorectal cancer was lower in MSH6 mutation carriers, but the difference was not significant (P = 0.0854). MSI analysis in colorectal tumors had a sensitivity of 86% in predicting a MMR defect. IHC in all tumors had a sensitivity of 90% in predicting a mutation in MSH6. CONCLUSIONS: We recommend starting colonoscopic surveillance in female MSH6 mutation carriers from age 30 years. Prophylactic hysterectomy might be considered in carriers older than 50 years. MSI and IHC analysis are sensitive tools to identify families eligible for MSH6 mutation analysis.