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K Offit

Publications and source records attributed to K Offit.

At least 19 recordsLinked to original sources
PubMed2006

Accuracy of BRCA1 and BRCA2 founder mutation analysis in formalin-fixed and paraffin-embedded (FFPE) tissue.

BACKGROUND: A major limitation in counseling unaffected women from families with inherited breast and ovarian cancer is that a "true-negative" interpretation of wild type BRCA analysis of the proband cannot be inferred in the absence of demonstration of a BRCA mutation segregating in the kindred. Documentation of familial BRCA mutations from paraffin-derived DNA of deceased patients has been limited due to reports of technical complications leading to lack of reproducibility of BRCA testing of archival material. METHODS: DNA was extracted from formalin-fixed paraffin-embedded (FFPE) morphologically normal tissue of 161 blinded, coded samples from women previously genotyped for the three Ashkenazi Jewish BRCA founder mutations from lymphocyte-derived DNA. Multiplex PCR followed by denaturing polyacrylamide gel electrophoresis was performed for the three founder mutations to determine if analysis on FFPE tissue could produce results concordant with those of the lymphocyte-derived DNA. RESULTS: After disclosure of the sample codes, the results were compared with the original lymphocyte-derived DNA genotypes. Excluding one sample unevaluable due to PCR failure, there was 100% concordance of 160 genotypes (120 mutation samples) derived from DNA from archival FFPE tissue compared to peripheral lymphocytes. CONCLUSIONS: The method described reliably detected BRCA founder mutations in archival DNA derived from FFPE tissue. These results suggests that this technique may be useful in clinical settings to inform wild type BRCA results of unaffected probands, leading to avoidance of unnecessary intensified surveillance or risk-reducing surgery. With further validation this approach can also be applied to other populations where founder mutations are observed.

DNA↗
PubMed2004

Referral for cancer genetics consultation: a review and compilation of risk assessment criteria.

BACKGROUND: There have been many papers on the diagnostic criteria for specific hereditary cancer susceptibility syndromes and the likelihood that an individual has a germline mutation in one of the various cancer susceptibility genes. To assist health care professionals in deciding when a cancer genetics consultation is appropriate, available reports were critically reviewed in order to develop a single set of risk assessment criteria. METHODS: The criteria were based on a comprehensive review of publications describing diagnostic criteria for hereditary cancer syndromes and risk to first degree relatives of cancer patients. Priority was given to diagnostic criteria from consensus statements (for example, those from the National Comprehensive Cancer Network). Expert opinion from study personnel was then used to adopt a single set of criteria from other publications whenever guidelines differed. RESULTS: Based on family history, a set of criteria was developed to identify patients at risk for a hereditary cancer susceptibility syndrome, patients with moderate risk who might benefit from increased cancer surveillance, and patients who are at average risk. The criteria were applied to 4360 individuals who provided their cancer family history between July 1999 and April 2002, using a touch screen computer system in the lobby of a comprehensive cancer centre. They categorised an acceptable number of users into each risk level: 14.9% high risk, 13.7% moderate risk, and 59.6% average risk; 11.8% provided insufficient information for risk assessment. CONCLUSIONS: These criteria should improve ease of referral and promote consistency across centres when evaluating patients for referral to cancer genetics specialists.

Female↗
PubMed2002

The founder mutation MSH2*1906G-->C is an important cause of hereditary nonpolyposis colorectal cancer in the Ashkenazi Jewish population.

Hereditary nonpolyposis colorectal cancer (HNPCC) is caused by mutations in the mismatch-repair genes. We report here the identification and characterization of a founder mutation in MSH2 in the Ashkenazi Jewish population. We identified a nucleotide substitution, MSH2*1906G-->C, which results in a substitution of proline for alanine at codon 636 in the MSH2 protein. This allele was identified in 15 unrelated Ashkenazi Jewish families with HNPCC, most of which meet the Amsterdam criteria. Genotype analysis of 18 polymorphic loci within and flanking MSH2 suggested a single origin for the mutation. All colorectal cancers tested showed microsatellite instability and absence of MSH2 protein, by immunohistochemical analysis. In an analysis of a population-based incident series of 686 Ashkenazi Jews from Israel who have colorectal cancer, we identified 3 (0.44%) mutation carriers. Persons with a family history of colorectal or endometrial cancer were more likely to carry the mutation than were those without such a family history (P=.042), and those with colorectal cancer who carried the mutation were, on average, younger than affected individuals who did not carry it (P=.033). The mutation was not detected in either 566 unaffected Ashkenazi Jews from Israel or 1,022 control individuals from New York. In hospital-based series, the 1906C allele was identified in 5/463 Ashkenazi Jews with colorectal cancer, in 2/197 with endometrial cancer, and in 0/83 with ovarian cancer. When families identified by family history and in case series are included, 25 apparently unrelated Ashkenazi Jewish families have been found to harbor this mutation. Although this pathogenic mutation is not frequent in the Ashkenazi Jewish population (accounting for 2%-3% of colorectal cancer in those whose age at diagnosis is <60 years), it is highly penetrant and accounts for approximately one-third of HNPCC in Ashkenazi Jewish families that fulfill the Amsterdam criteria.

Alanine↗
PubMed2002

Analysis of mismatch repair defects in the familial occurrence of lymphoma and colorectal cancer.

Hereditary non-polyposis colon cancer (HNPCC) is an autosomal dominant disorder featuring familial clustering of colorectal and/or endometrial cancer, and other malignancies. Except for a rare case report, Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) have not been considered part of HNPCC. Recent murine models for HNPCC have shown an increased incidence of B- and T-cell lymphoma, as well as tumors of the gastrointestinal tract and other organ systems, involving defects in genes resulting in faulty mismatch repair (MMR) of DNA. These MMR genes include MLH1, MSH2, MSH3, MSH6, PMS1 and PMS2. We sought to analyze the occurrence of NHL and HD in families with clusters of colorectal cancers (CRC). Probands from 21 kindreds were classified as HNPCC (3), HNPCC-like (5), and HNPCC-variant (13); seen and followed by Clinical Genetics at Memorial Hospital the kindreds were assessed for the occurrence of NHL or HD. Of the 21 pedigrees, a total of 37 patients were identified who were diagnosed with leukemia, lymphoma, or HD. Fourteen of the 37 patients with a diagnosis of NHL or HD were further classified and showed varying histologies ranging from chronic lymphocytic leukemia/small lymphocytic lymphoma (2), mycosis fungoides (1), follicular lymphoma (1), extranodal marginal zone lymphoma of MALT type (2), diffuse large B-cell lymphoma (4), nodular sclerosis HD (3), and mixed cellularity HD (1). Microsatellite instability studies were performed on 6 cases but none showed evidence of replication error repair defects. Immunohistochemical stains performed on paraffin sections from these 6 representative cases showed differential protein expression of MLH1, MSH2, MSH6, and PMS2 when compared to normal reactive tissues from the same patient but showed no significant differences when compared to controls of non-familial, sporadic lymphomas. These results suggest that lymphomas arising in the setting of familial CRC do not bear the molecular hallmarks of HNPCC. Further studies are needed to explain the differential patterns of expression of RER-associated proteins in lymphomas, as well as the association of lymphomas and possibly renal cell cancers in a subset of kindreds in which CRC clustering is evident.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Risk of endometrial carcinoma associated with BRCA mutation.

OBJECTIVE: Inherited mutations in the BRCA1 or BRCA2 genes are associated with a greatly increased lifetime risk of breast and ovarian cancers and a modestly increased risk of several other cancer types. Several case reports of endometrial carcinoma in women with a BRCA mutation have led to speculation regarding the effect of these genes on the risk of endometrial cancer. The purpose of this study was to test the hypothesis that germline mutation of a BRCA gene is associated with an increased risk of endometrial carcinoma. METHODS: A retrospective cohort of 199 consecutive Ashkenazi Jewish patients with endometrial carcinoma was identified from a 12-year period at this institution. All were genotyped for the three BRCA founder mutations (185delAG and 5382insC in BRCA1 and 6174delT in BRCA2) that exist in this population, and the case frequency was compared to the known population frequency of these mutations. Additionally, endometrial carcinomas occurring in patients with BRCA mutations were assessed for somatic loss of the wild-type BRCA allele. RESULTS: Germline BRCA mutations were identified in 3 (1 in BRCA1 and two in BRCA2) of 199 (1.5%) patients, compared to a frequency of 2.0% in this population generally. A relative risk of endometrial carcinoma associated with BRCA mutation, as estimated by the odds ratio, was calculated as 0.75 (95% CI = 0.24--2.34; P = 0.6). Loss of the wild-type BRCA allele was observed in two of three tumors associated with a BRCA mutation. CONCLUSIONS: For individuals with a germline BRCA mutation, the lifetime risk of endometrial carcinoma is not increased.

Aged↗
PubMed2001

The lifetime risks of breast cancer in Ashkenazi Jewish carriers of BRCA1 and BRCA2 mutations.

Several studies using families with multiple occurrences of breast cancer have provided evidence for a very high lifetime penetrance in carriers of BRCA1 or BRCA2 mutations. However, there are reasons to suspect that the estimates of penetrance from studies of cancer families may be inflated. Access to the genotypes of incident cases of breast cancer in three hospitals and from a large series of unaffected survey participants provided the basis for direct estimation of the age-specific relative risks attributable to these mutations, and the resulting lifetime penetrance, without any reference to familial aggregation of cancer. Cases were identified from incident series of Jewish patients treated for primary breast cancer at the three hospitals. Control data were obtained from the large series of Jewish women recruited in the Washington, D.C., area by investigators at the National Cancer Institute and limited to 3434 women with no previous history of breast or ovarian cancer. All subjects were genotyped for the three mutations that are relatively common in Ashkenazi Jews, namely 185delAG and 5382 insC in BRCA1 and 6174delT in BRCA2. For BRCA1, the relative risks of breast cancer were estimated to be 21.6 in women under 40 years of age, 9.6 in women 40-49 years of age, and 7.6 in women > or = 50 years of age. On the basis of these estimates, the penetrance of breast cancer at age 70 among BRCA1 mutation carriers is estimated to be 46% (95% confidence, 31%-80%) rising to 59% (95% confidence, 40%-93%) at age 80. For BRCA2, the relative risks in the same three age categories were estimated to be 3.3, 3.3, and 4.6, respectively, resulting in a penetrance at age 70 of 26% (95% confidence, 14%-50%) rising to 38% (95% confidence, 20%-68%) at age 80. The lifetime risk of breast cancer in Jewish women who are mutation carriers estimated via this approach is substantially lower than the reported lifetime risks estimated using multiple-case families. The risks appear to be different for carriers of BRCA1 and BRCA2 mutations.

Adult↗
PubMed2001

A single nucleotide polymorphism in the 5' untranslated region of RAD51 and risk of cancer among BRCA1/2 mutation carriers.

RAD51 colocalizes with both BRCA1 and BRCA2, and genetic variants in RAD51 would be candidate BRCA1/2 modifiers. We searched for RAD51 polymorphisms by sequencing 20 individuals. We compared the polymorphism allele frequencies between female BRCA1/2 mutation carriers with and without breast or ovarian cancer and between population-based ovarian cancer cases with BRCA1/2 mutations to cases and controls without mutations. We discovered two single nucleotide polymorphisms (SNPs) at positions 135 g-->c and 172 g-->t of the 5' untranslated region. In an initial group of BRCA1/2 mutation carriers, 14 (21%) of 67 breast cancer cases carried a "c" allele at RAD51:135 g-->c, whereas 8 (7%) of 119 women without breast cancer carried this allele. In a second set of 466 mutation carriers from three centers, the association of RAD51:135 g-->c with breast cancer risk was not confirmed. Analyses restricted to the 216 BRCA2 mutation carriers, however, showed a statistically significant association of the 135 "c" allele with the risk of breast cancer (adjusted odds ratio, 3.2; 95% confidence limit, 1.4-40). BRCA1/2 mutation carriers with ovarian cancer were only about one half as likely to carry the RAD51:135 g-->c SNP. Analysis of the RAD51:135 g-->c SNP in 738 subjects from an Israeli ovarian cancer case-control study was consistent with a lower risk of ovarian cancer among BRCA1/2 mutation carriers with the "c" allele. We have identified a RAD51 5' untranslated region SNP that may be associated with an increased risk of breast cancer and a lower risk of ovarian cancer among BRCA2 mutation carriers. The biochemical basis of this risk modifier is currently unknown.

Adult↗
PubMed2000

Absence of premalignant histologic, molecular, or cell biologic alterations in prophylactic oophorectomy specimens from BRCA1 heterozygotes.

BACKGROUND: The high mortality associated with ovarian carcinoma is largely a reflection of the inability to diagnose the disease at an early stage; the identification of a histologic lesion or molecular marker associated early stages of transformation would represent an important advance in understanding the natural history of this cancer. The existence of individuals with germline mutations in the ovarian and breast carcinoma susceptibility gene BRCA1 represents a unique opportunity to search for such premalignant alterations in ovarian tissues that are at unusually high risk for tumorigenesis. In this study, the authors addressed the hypothesis that pathologically normal ovaries removed from BRCA1 heterozygotes are likely to display premalignant histologic, molecular, and/or cell biologic alterations that may provide insight into early stages of ovarian tumorigenesis. METHODS: Ovarian tissues from 18 BRCA1 heterozygotes and from 20 age-matched controls were examined in a blinded fashion for histologic evidence of surface epithelial pseudostratification, epithelial inclusion cysts, deep cortical invaginations of surface epithelium, increased stromal cell activity, and surface papillomatosis. Immunohistochemical analyses for expression of BRCA1, p53, and ERBB-2 and quantitation of cell proliferation (Ki-67 expression) and apoptosis (TUNEL assay), were also performed on all specimens. RESULTS: Although histologic alterations were observed, there was no difference in frequency between cases and controls. Analysis of BRCA1 expression revealed ubiquitous nuclear immunoreactivity in the surface epithelial cells of all ovaries. Similarly, no evidence was found of p53 overexpression in any ovarian tissue or of a difference in ERBB-2 expression between cases and controls. Finally, no differences were observed in epithelial cell proliferation or apoptosis. CONCLUSIONS: Clinically, normal ovaries from BRCA1 heterozygotes do not show evidence of premalignant alterations in histology, molecular markers, cell proliferation, or apoptosis, indicating that such changes are likely rare.

Adult↗
PubMed1999

Breast conservation therapy for invasive breast cancer in Ashkenazi women with BRCA gene founder mutations.

BACKGROUND: Germline mutations in the BRCA1 and BRCA2 genes are associated with an increased risk of breast cancer. Whether women with breast cancer who have inherited mutations in these genes have a different outcome after breast conservation therapy than women with "sporadic" cancer is unresolved. Consequently, we compared the outcomes after breast conservation therapy in Ashkenazi women with or without germline mutations in BRCA1 and/or BRCA2 (hereafter called BRCA). METHODS: We studied 305 women of Ashkenazi Jewish descent undergoing breast-conserving treatment for 329 invasive breast cancers. We reviewed their clinical records, retrieved their archival tissue samples, and tested those samples for the founder mutations BRCA1 185delAG, BRCA1 5382insC, and BRCA2 6174delT. Genetic results were linked to clinical data and outcomes by univariate and multivariate analyses. All Pvalues are two-sided. RESULTS: We detected mutations in BRCA genes in 28 of 305 women. Women with BRCA mutations were more likely to be diagnosed with cancer before the age of 50 years (P<.001) and to have lymph node involvement (P =.04). Ipsilateral breast tumor recurrence was more common in women with BRCA mutations, although this did not reach statistical significance (relative risk [RR] = 1.79; 95% confidence interval [CI] = 0.64-5.03). Women with mutations were more likely to develop contralateral breast cancer (RR = 3.50; 95% CI = 1.78-8.74; P =.001). Distant disease-free survival was shorter in women with mutations (66.2% versus 84.3% at 10 years; P =.05), as was breast cancer-specific survival (71.9% versus 87.2% at 10 years; P =.02). Tumor stage and nodal status, but not mutation status, were predictive of distant disease-free and breast cancer-specific survival in multivariate analysis. CONCLUSIONS: Women with BRCA founder mutations are at increased risk for breast cancer-related events after breast conservation. However, mutation status is not an independent predictor of survival and should not influence decisions regarding adjuvant therapy. The increased contralateral breast cancer risk in women heterozygous for BRCA mutations mandates careful surveillance.

Analysis of Variance↗
PubMed1999

TbetaR-I(6A) is a candidate tumor susceptibility allele.

We have previously described a type I transforming growth factor (TGF)-beta receptor (TbetaR-I) polymorphic allele, TbetaR-I(6A), that has a deletion of three alanines from a nine-alanine stretch. We observed a higher than expected number of TbetaR-I(6A) homozygotes among tumor and nontumor DNA from patients with a diagnosis of cancer. To test the hypothesis that TbetaR-I(6A) homozygosity is associated with cancer, we performed a case-control study in patients with a diagnosis of cancer and matched healthy individuals with no history of cancer and who were identical in their gender and their geographical and ethnic background to determine the relative germ-line frequencies of this allele. We found nine TbetaR-I(6A) homozygotes among 851 patients with cancer. In comparison, there were no TbetaR-I(6A) homozygotes among 735 healthy volunteers (P < 0.01). We also observed an excess of TbetaR-I(6A) heterozygotes in cancer cases compared to controls (14.6% versus 10.6%; P = 0.02, Fisher's exact test). A subset analysis revealed that 4 of 112 patients with colorectal cancer were TbetaR-I(6A) homozygotes (P < 0.01). Using mink lung epithelial cell lines devoid of TbetaR-I, we established stably transfected TbetaR-I and TbetaR-I(6A) cell lines. We found that, compared to TbetaR-I, TbetaR-I(6A) was impaired as a mediator of TGF-beta antiproliferative signals. We conclude that TbetaR-I(6A) acts as a tumor susceptibility allele that may contribute to the development of cancer, especially colon cancer, by means of reduced TGF-beta-mediated growth inhibition.

Activin Receptors, Type I↗
PubMed1998

Molecular genetic characterization of BRCA1- and BRCA2-linked hereditary ovarian cancers.

Hereditary ovarian cancers associated with germline mutations in either BRCA1 or BRCA2 were studied to determine whether somatic mutation of the P53 gene is required for BRCA-linked ovarian tumorigenesis and further, whether the spectrum of additional somatic molecular genetic alterations present in these tumors differs from that known to exist in sporadic ovarian cancers. Forty tumors, 29 linked to BRCA1 and 11 linked to BRCA2, were examined for mutational alterations in P53, K-RAS, ERBB-2, C-MYC, and AKT2. The presence of a P53 mutation in 80% of these cancers indicates that P53 mutation is common but not required for BRCA-linked ovarian tumorigenesis; notably, a significantly higher proportion of the P53 mutations in BRCA2-linked cancers were deletions or insertions compared with the more typical spectrum of missense mutations seen in BRCA1-linked cancers. Additionally, BRCA-linked ovarian carcinomas seem to develop through a unique pathway of tumorigenesis that does not involve mutation of K-RAS or amplification of ERBB-2, C-MYC, or AKT2.

Arabidopsis Proteins↗
PubMed1998

Chromosomal and gene amplification in diffuse large B-cell lymphoma.

Chromosomal translocations leading to deregulation of specific oncogenes characterize approximately 50% of cases of diffuse large B-cell lymphomas (DLBL). To characterize additional genetic features that may be of value in delineating the clinical characteristics of DLBL, we studied a panel of 96 cases at diagnosis consecutively ascertained at the Memorial Sloan-Kettering Cancer Center (MSKCC) for incidence of gene amplification, a genetic abnormality previously shown to be associated with tumor progression and clinical outcome. A subset of 20 cases was subjected to comparative genomic hybridization (CGH) analysis, which identified nine sites of chromosomal amplification (1q21-23, 2p12-16, 8q24, 9q34, 12q12-14, 13q32, 16p12, 18q21-22, and 22q12). Candidate amplified genes mapped to these sites were selected for further analysis based on their known roles in lymphoid cell and lymphoma development, and/or history of amplification in tumors. Probes for six genes, which fulfilled these criteria, REL (2p12-16), MYC (8q24), BCL2 (18q21), GLI, CDK4, and MDM2 (12q13-14), were used in a quantitative Southern blotting analysis of the 96 DLBL DNAs. Each of these genes was amplified (four or more copies) with incidence ranging from 11% to 23%. This analysis is consistent with our previous finding that REL amplification is associated with extranodal presentation. In addition, BCL2 rearrangement and/or REL, MYC, BCL2, GLI, CDK4, and MDM2 amplification was associated with advanced stage disease. These data show, for the first time, that amplification of chromosomal regions and genes is a frequent phenomenon in DLBL and demonstrates their potential significance in lymphomagenesis.

Chromosome Mapping↗