A636P is associated with early-onset colon cancer in Ashkenazi Jews

Cancer Susceptibility Genetic Testing in a High-Risk Cohort of Urban Ashkenazi Jewish Individuals

Prior to 2013, genetic testing for Ashkenazi Jewish (AJ) individuals primarily consisted of the three-site BRCA1/BRCA2 AJ panel, full sequencing of BRCA1/2, or the Lynch syndrome mismatch repair genes. Multigene panel testing became more widely available in 2013, but limited data are available regarding the impact of multigene panel testing for AJ individuals. Here, we report the frequency of cancer susceptibility gene mutations in a cohort of 427 AJ individuals seen in the Cancer Risk Clinic at The University of Chicago. We found that 29% of affected and 37% of unaffected individuals carried a pathogenic mutation (32% of overall cohort), primarily known familial mutations in BRCA1/2. A minority of mutations were identified in non-BRCA1/2 genes and consisted mainly of AJ founder mutations in CHEK2, APC, and the mismatch repair genes. A panel of AJ founder mutations would have identified the majority (94%) of mutations in clinically actionable genes in both affected and unaffected patients. Based on recent cost-effectiveness studies, offering all AJ individuals a founder mutation panel may be a cost-effective cancer prevention strategy.

MSH2 Loss in Primary Prostate Cancer

Purpose: Inactivation of mismatch repair (MMR) genes may predict sensitivity to immunotherapy in metastatic prostate cancers. We studied primary prostate tumors with MMR defects.Experimental Design: A total of 1,133 primary prostatic adenocarcinomas and 43 prostatic small cell carcinomas (NEPC) were screened by MSH2 immunohistochemistry with confirmation by next-generation sequencing (NGS). Microsatellite instability (MSI) was assessed by PCR and NGS (mSINGS).Results: Of primary adenocarcinomas and NEPC, 1.2% (14/1,176) had MSH2 loss. Overall, 8% (7/91) of adenocarcinomas with primary Gleason pattern 5 (Gleason score 9-10) had MSH2 loss compared with 0.4% (5/1,042) of tumors with any other scores (P < 0.05). Five percent (2/43) of NEPC had MSH2 loss. MSH2 was generally homogenously lost, suggesting it was an early/clonal event. NGS confirmed MSH2 loss-of-function alterations in all (12/12) samples, with biallelic inactivation in 83% (10/12) and hypermutation in 83% (10/12). Overall, 61% (8/13) and 58% (7/12) of patients had definite MSI by PCR and mSINGS, respectively. Three patients (25%) had germline mutations in MSH2 Tumors with MSH2 loss had a higher density of infiltrating CD8+ lymphocytes compared with grade-matched controls without MSH2 loss (390 vs. 76 cells/mm2; P = 0.008), and CD8+ density was correlated with mutation burden among cases with MSH2 loss (r = 0.72, P = 0.005). T-cell receptor sequencing on a subset revealed a trend toward higher clonality in cases versus controls.Conclusions: Loss of MSH2 protein is correlated with MSH2 inactivation, hypermutation, and higher tumor-infiltrating lymphocyte density, and appears most common among very high-grade primary tumors, for which routine screening may be warranted if validated in additional cohorts. Clin Cancer Res; 23(22); 6863-74. ©2017 AACR.

Systematic immunohistochemistry screening for Lynch syndrome in early age-of-onset colorectal cancer patients undergoing surgical resection

BACKGROUND

Lynch syndrome (LS), defined by a deleterious (pathogenic) germline mutation in a mismatch repair (MMR) gene, is characterized by early age-of-onset colorectal cancer (CRC). Because clinical criteria for LS, such as the Amsterdam II Criteria, may miss cases, reflex tumor tissue testing of all CRC patients for LS has been proposed. Our study describes the impact of routine immunohistochemistry (IHC) analysis of tumor tissue for loss of MMR protein expression in early age-of-onset CRC patients undergoing resection.

STUDY DESIGN

A prospective institutional program was established to perform IHC analysis on all early age-of-onset (≤50 years) CRC patients undergoing resection. Patients with abnormal IHC analysis were referred to the Clinical Genetics Service for further evaluation. The study cohort excluded patients with other polyposis syndromes and inflammatory bowel disease.

RESULTS

IHC was performed on 198 patients from July 2006 to June 2010. The median age was 42.8 years (range 23.1 to 50.6 years). Abnormal IHC was reported in 38 (19.1%) patients, and 22 (57.8%) with abnormal IHC analysis had germline genetic testing. Seventeen (77.2%) had an alteration detected in an MMR gene: 10 were known to be deleterious mutations and 7 were variants of uncertain significance. Overall, LS was detected in 5.1% of patients. Only 2 of the 10 (20%) with a deleterious mutation actually met the Amsterdam II Criteria.

CONCLUSIONS

Reflex IHC testing for LS on early age-of-onset CRC patients undergoing resection is feasible at the institutional level. This strategy identifies a substantial number of LS patients who would have been missed if genetic testing was based on the Amsterdam II Criteria alone.

High risk of colorectal and endometrial cancer in Ashkenazi families with the MSH2 A636P founder mutation

BACKGROUND & AIMS

The MSH2 A636P mutation is a founder mutation in Ashkenazi Jews that causes Lynch syndrome, with a prevalence of 0.4%-0.7%. Estimates of age-specific cumulative risk and lifetime risk for colorectal cancer (CRC) and endometrial cancer (EC) specific to carriers of this mutation are not available.

METHODS

We studied 27 families with MSH2 A636P gene mutations identified in Israel; 13 were identified via a population-based, case-control study and 14 were identified from a clinical genetics service. Age-specific cumulative risks (penetrance) and hazard ratio (HR) estimates of CRC and EC risks were calculated and compared with the general Ashkenazi population using modified segregation analysis. An ascertainment-corrected likelihood that combined population-based and clinic-based sampling provided a powerful analysis for estimating penetrance. We analyzed 74 cases of CRC (40 in the clinic series and 34 in the population-based series), diagnosed at median ages of 50 years (men) and 49 years (women) in the combined sample.

RESULTS

The cumulative risk of CRC at age 70 was 61.62% for men (95% confidence interval [CI], 37.49%-76.45%) and 61.08% for women (95% CI, 39.39%-75.14%), with overall HRs of 31.8 (19.9-51.0) and 41.8 (27.4-64.0), respectively. There were 28 cases of EC, diagnosed at a median age of 53.0 years. The cumulative risk of EC was 55.64% (95% CI, 33.07%-70.58%) with an overall HR of 66.7 (41.7-106.7).

CONCLUSIONS

Lifetime risks of CRC and EC in MSH2 A636P carriers are high even after adjusting for ascertainment. These estimates are valuable for patients and providers; specialized cancer screening is necessary for carriers of this mutation.

Association of familial colorectal cancer with variants in the E-cadherin (CDH1) and cyclin D1 (CCND1) genes

INTRODUCTION

About 20% of colorectal cancer (CRC) patients show some kind of familiarity, which might be caused by yet unknown combinations of low penetrance susceptibility genes. We aimed to identify genetic factors for familial CRC (fCRC) in a unique study design that includes phenotypic extremes as represented by fCRC cases and 'hyper-normal' controls without CRC history and no adenomatous polyps on colonoscopy.

MATERIALS AND METHODS

Candidate gene variants were determined by allele-specific amplification (SLC10A2 c.169C>T and c.171G>T) and restriction fragment length polymorphism assays (CCND1 c.870A>G; CDH1 -160C>A; TP53 R72P; VDR T2M). In total, 98 patients with fCRC, 96 patients with sporadic CRC, and 220 hyper-normal controls were included.

RESULTS

The minor allele of the CDH1 -160C>A polymorphism occurred significantly more often in controls compared to fCRC cases (OR = 0.664; p = 0.042). Homozygosity of the minor allele was significantly associated with affiliation to the control group (OR = 0.577; p = 0.029), indicating that both heterozygous and homozygous carriers of the common allele are at-risk for CRC. With respect to the CCND1 c.870A>G mutation, comparison of fCRC and sporadic CRC cases showed that A/A homozygosity was more common than G/G homozygosity among fCRC patients compared to controls (OR = 2.119; p = 0.045). However, no differences in allele or genotype frequencies were detected between sporadic CRC cases and controls, and no associations were observed for SLC10A2, TP53, and VDR polymorphisms.

CONCLUSIONS

We report a potential association of variants in the CCND1 and CDH1 genes with fCRC using a unique study design with phenotypic extremes.

Single-amplicon MSH2 A636P mutation testing in Ashkenazi Jewish patients with colorectal cancer: role in presurgical management

OBJECTIVE

This study summarizes our initial experience with prospective, single-amplicon (mutation-specific) A636P testing in Ashkenazi Jewish patients at risk for Hereditary Nonpolyposis Colorectal Cancer (HNPCC).

SUMMARY BACKGROUND DATA

We previously described a founder mutation, MSH2*1906G >C (A636P) that causes HNPCC in 8/1345 (0.59%) of Ashkenazim with colorectal cancer. The mutation was more common in Ashkenazim diagnosed at <or=40 years (7%).

METHODS

Twenty-seven Ashkenazi probands at risk for HNPCC were ascertained. Single-amplicon A636P testing was performed on 21 by polymerase chain reaction of exon 12 of MSH2, followed by direct DNA sequencing. Mutational analysis of the entire open reading frame of MLH1 and MSH2 was performed on 7 by PCR of each exon, followed by heteroduplex analysis using denaturing high-performance liquid chromatography and direct sequencing of exons with variant chromatographs. One patient received both studies,

RESULTS

The A636P mutation was detected in 3/21 (14%) prospectively evaluated patients using single amplicon testing. In 6 patients, the entire open reading frame of MLH1 and MSH2 was analyzed, and 1 additional A636P carrier and 2 carriers of previously unrecognized mutations were identified. The A636P mutation was present in 2 patients who met Amsterdam criteria and in 2 patients who did not.

CONCLUSIONS

Although rare in the general population, A636P mutations are found at increased frequency in Ashkenazim with a personal or family history of colorectal or other HNPCC-associated cancers. This inexpensive and rapid approach may be useful preoperatively in helping determine the extent of colon resection for a subset of patients.

Perceptions of genetic testing for cancer predisposition among Ashkenazi Jewish women

BACKGROUND

Clinical genetic testing can help identify individuals who are predisposed to a variety of diseases and conditions; thus, it is important to understand attitudes and perceptions of individuals who may consider or who may be offered such testing.

METHODS

We examined knowledge and attitudes about cancer genetic testing among 59 women of Ashkenazi Jewish descent (age 25-80 years) through six focus group discussions. Participants were asked about their knowledge and experience with hereditary conditions and genetic testing, and attitudes regarding risk management options, genetic privacy, and potential discrimination issues.

RESULTS

Although 54% reported having a personal and/or some family history of breast, ovarian, or colorectal cancer, none had undergone cancer genetic counseling or testing and few expressed an interest or intention in doing so. While most endorsed benefits of genetic testing for those with a significant cancer family history, women also expressed concerns over the possible distress of learning that one carried a cancer-predisposing mutation and suggested that increasing cancer screening practices may be preferable to having genetic testing. Participants doubted the ability of state genetic privacy legislation to protect against insurance or employment discrimination.

CONCLUSION

Findings underscore the need for public education on the broad range of benefits and limitations associated with genetic testing, in order to help consumers to appropriately interpret complex information and make decisions about these services.

Pathogenicity of MSH2 missense mutations is typically associated with impaired repair capability of the mutated protein

BACKGROUND & AIMS

Inherited deleterious mutations in mismatch repair genes MLH1, MSH2, and MSH6 predispose to hereditary nonpolyposis colorectal cancer. A major diagnostic challenge is the difficulty in evaluating the pathogenicity of missense mutations. Previously we showed that most missense variants in MSH6 do not impair MMR capability and are associated with no or low cancer susceptibility, whereas in MLH1, functional studies distinguished nontruncating mutations with severe defects from those not or slightly impaired in protein expression or function. The present study was undertaken to evaluate the pathogenicity of inherited missense mutations in MSH2.

METHODS

Fifteen mutated MSH2 proteins including 14 amino acid substitutions and one in-frame deletion were tested for expression/stability, MSH2/MSH6 interaction, and repair efficiency. The genetic and biochemical data were correlated with the clinical data. Comparative sequence analysis was performed to assess the value of sequence homology as a tool for predicting functional results.

RESULTS

None of the studied MSH2 mutations destroyed the protein or abolished MSH2/MSH6 interaction, whereas 12 mutations impaired the repair capability of the protein. Comparative sequence analysis correctly predicted functional studies for 13 of 14 amino acid substitutions.

CONCLUSIONS

Interpretation was pathogenic for 12, nonpathogenic for 2, and contradictory for 1 mutation. The pathogenicity could not be distinguished unambiguously by phenotypic characteristics, although correlation between the absence of staining for MSH2 and pathogenicity of the missense mutation was notable. Unlike in MSH6 and MLH1, the pathogenicity of missense mutations in MSH2 was always associated with impaired repair capability of the mutated protein.

The I1307K APC polymorphism in Ashkenazi Jews with colorectal cancer: clinical and pathologic features

Colorectal cancer is common in Ashkenazi Jews. The I1307K APC mutation occurs in 6-7% of Ashkenazi Jews and increases the risk of colorectal cancer. This study aimed to describe the clinical, pathologic and epidemiologic features of colorectal cancer in I1307K carriers to determine whether there were any features which might warrant individual screening for the mutation. In all, 215 Ashkenazi Jews with a personal history of colorectal cancer were enrolled. Clinical and family history, pathology reports, and slides were obtained and blood drawn for I1307K determination. The presence of the mutation was determined by PCR from white blood cell DNA. Colorectal cancer pathology slides were read in a blinded fashion. Of the 215 enrolled patients, 26 (12.1%) tested positive for I1307K. There was no difference in the pathologic features between colorectal cancers in Ashkenazi carriers compared to noncarriers. There was no difference in the age at diagnosis or history of second or other primaries. Carriers had an increased likelihood of having a first-degree relative with colorectal cancer (50%) compared to noncarriers (28%, P < 0.04). We could find no distinguishing feature other than family history that characterizes I1307K positive colorectal cancers. We could find no group of Ashkenazi Jews with colorectal cancer for whom screening for I1307K would be clinically useful.

A636P testing in Ashkenazi Jews

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominantly inherited colorectal cancer syndrome attributable to mutations in one of several DNA mismatch repair genes, most commonly MLH1 and MSH2 . In certain populations, founder mutations account for a substantial portion of HNPCC. In this report we summarize the literature and our personal experience testing for a specific founder mutation in the Ashkenazi Jewish population, MSH2*1906G > C , also known as A636P. Although rare in the general population, the A636P mutation is detected in up to 7% of Ashkenazi Jewish patients with early age-of-onset colorectal cancer, and may account for up to one third of HNPCC in the Ashkenazi Jewish population. In addition, we summarize our initial experience with a prospective A636P testing protocol aimed at Ashkenazi Jewish patients at high or intermediate risk for harboring the A636P mutation.

The Jewish people: their ethnic history, genetic disorders and specific cancer susceptibility

The Jews are an ancient and unique group of people linked by language, religion and customs in spite of their major geographical shifts, expulsions, forced conversions and massacres throughout their entire history. As a result of these historical events that led to repeated migration, the Jewish people became dispersed into various ethnic sub-groups. Between these ethnic groups exists heterogeneity, as well as some similarities, to the populations amongst whom they lived. Rare genetic diseases have been reported to be prevalent among the different groups of Jews, which for the most part can be explained by random genetic drift together with intra-familial marriages. In this publication, we will briefly discuss the origin of the various ethnic groups and some of the genetic diseases commonly found in them, with emphasis on the Ashkenazim, their prevalent genetic diseases and cancer susceptibility.

Cancer in Jews: introduction and overview

This article is based upon a literature overview of cancer in Jews. It involves a comparison of variation in incidence and prevalence rates between Jews and non-Jews. However, the reader must exercise a certain amount of skepticism when considering secular changes in cancer incidence and prevalence and the public health implications of such cancer variation. Ashkenazi Jews have a lifetime CRC risk of 9--15%. This elevated CRC risk is similar to that of individuals in the "familial risk'' category, and differs strikingly from the 5-6% CRC risk for non-Ashkenazi members of general Western populations. A MedLine search tested the hypothesis that site-specific and/or all-cancer incidence and mortality rates are either higher or lower than expected in Ashkenazi Jews worldwide, when compared with reference populations. Results showed that all cancer incidence and mortality is not higher in Ashkenazi Jews when compared to North American non-Hispanic whites. Indeed, rates for some cancers, such as carcinoma of the lung in Ashkenazi males, are low; this example is likely attributable in large part to decreased tobacco use. Carcinoma of the ovary, pancreas, stomach, and non-Hodgkin's lymphoma have a higher incidence rate in Ashkenazi. Even though BRCA1 and BRCA2 founder mutations which predispose to carcinoma of the breast and ovary appear increased in Ashkenazi breast cancer affected women, there was no evidence supporting an elevated risk of breast cancer among Ashkenazi women. Our primary concern, however, is that Ashkenazi Jews may have one of the highest lifetime CRC risks of any ethnic group in the world, a risk that diverges significantly from that of the general population; therein, it logically calls for more intensive CRC screening guidelines. We have emphasized that the reader use caution in the interpretation of statistics which portray variation in incidence and prevalence figures for cancer in any racial, ethnic, or religious group, inclusive, of course, of Jews. Clearly, more research will be required in the interest of accuracy in the understanding of these cancer variations, since they portend the need for special cancer control strategies. A lesser degree of attention can then be given to carcinoma of the penis and uterine cervix, which occur very infrequently in Jews. We urge our colleagues to continue to probe further into these statistical differences in cancer's incidence and prevalence in order to garner a better understanding of cancer's etiology and pathogenesis.

Multiple rare variants in different genes account for multifactorial inherited susceptibility to colorectal adenomas

Clear-cut inherited Mendelian traits, such as familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer, account for <4% of colorectal cancers. Another 20% of all colorectal cancers are thought to occur in individuals with a significant inherited multifactorial susceptibility to colorectal cancer that is not obviously familial. Incompletely penetrant, comparatively rare missense variants in the adenomatous polyposis coli gene, which is responsible for familial adenomatous polyposis, have been described in patients with multiple colorectal adenomas. These variants represent a category of variation that has been suggested, quite generally, to account for a substantial fraction of such multifactorial inherited susceptibility. The aim of this study was to explore this rare variant hypothesis for multifactorial inheritance by using multiple colorectal adenomas as the model. Patients with multiple adenomas were screened for germ-line variants in a panel of candidate genes. Germ-line DNA was obtained from 124 patients with between 3 and 100 histologically proven synchronous or metachronous adenomatous polyps. All patients were tested for the adenomatous polyposis coli variants I1307K and E1317Q, and variants were also sought in AXIN1 (axin), CTNNB1 (beta-catenin), and the mismatch repair genes hMLH1 and hMSH2. The control group consisted of 483 random controls. Thirty of 124 (24.9%) patients carried potentially pathogenic germ-line variants as compared with 55 ( approximately 12%) of the controls. This overall difference is highly significant, suggesting that many rare variants collectively contribute to the inherited susceptibility to colorectal adenomas.

Genetic factors and colorectal cancer in Ashkenazi Jews

The observed increased incidence of colorectal cancer in Ashkenazi Jews compared to other populations is unexplained but likely has a genetic component. The I1307K APC polymorphism/mutation is carried by 6-8% of Ashkenazim and increases the risk of colorectal cancer 1.5-2 fold. There are few differences between the phenotype of colorectal cancer in I1307K carriers and sporadic cases. It is estimated that the mutation accounts for 6% of cases of colorectal cancer in Jews of Eastern European heritage. It should not be the subject of mass screening in Ashkenazi Jews, although it may be important in cases of familial colorectal cancer. Even rarer is the 1906G-->C MSH2 mutation carried by less than 1% of Ashkenazim, but as with other HNPCC mutations likely associated with a high risk of malignancy. Mutations at 15q13-14 are associated with the colorectal adenoma and carcinoma syndrome (CRAC) described in Ashkenazi families. The prevalence of the mutation is not known, nor its significance as a cause of colorectal cancer. Despite the paucity of genetic explanations for the high risk of colorectal cancer in Ashkenazim, that risk warrants aggressive colorectal cancer screening and particular attention to family history of malignancy in all Jews of Ashkenazi descent.

Hereditary ovarian cancer in Ashkenazi Jews

Ovarian cancer is the fourth leading cause of cancer deaths among American women. While women in both the Ashkenazi and non-Ashkenazi populations have an estimated 1.7% lifetime risk of acquiring malignancy, the proportion of hereditary ovarian cancer is much higher in the Ashkenazim. Most of this increased proportion of hereditary ovarian cancer risk is accounted for by inherited mutations in the BRCA1 and BRCA2 genes. In the Ashkenazi Jewish population, 29 to 41% of ovarian cancer is believed to be secondary to inheriting one of three founder mutations in BRCA 1 and BRCA 2, while only 10% of ovarian cancer is attributed to mutations of these genes in non-Ashkenazim. In the US population in general, it is estimated that between 1 out of 345 and 1 out of 1000 individuals carries a BRCA mutation, compared with approximately 1 in 40 individuals of Ashkenazi Jewish descent. The ovarian cancer risk up to age 70 associated with BRCA mutation carriers has been reported to be as high as 66% for BRCA1 and 27% for BRCA2 mutation carriers. Ovarian cancer in Ashkenazi kindreds has served as a model for the study of the histopathology of inherited ovarian cancers as well as for the study of risk reduction and screening among all women at inherited risk of ovarian cancer.