A segregation analysis of Barrett's esophagus and associated adenocarcinomas

Upper Gastrointestinal Cancers and the Role of Genetic Testing

Beyond the few established hereditary cancer syndromes with an upper gastrointestinal cancer component, there is increasing recognition of the contribution of novel pathogenic germline variants (gPVs) to upper gastrointestinal carcinogenesis. The detection of gPVs has potential implications for novel treatment approaches of the index cancer patient as well as long-term implications for surveillance and risk-reducing measures for cancer survivors and far-reaching implications for the patients' family. With widespread availability of multigene panel testing, new associations may be identified with germline-somatic integration being critical to determining true causality of novel gPVs. Comprehensive cancer care should incorporate both somatic and germline testing.

Age of diagnosis in familial Barrett's associated neoplasia

The identification of hereditary cancer genes for esophageal adenocarcinoma (EAC) and its precursor, Barrett's esophagus (BE), may prove critical for the development of novel prevention and treatment strategies. Specifically, efforts for detecting BE and EAC susceptibility genes have focused on families with three or more affected members, since these individuals have an earlier age onset compared to non-familial individuals. Given that the use of BE may overestimate the likelihood of disease heritability, we evaluated the age of diagnosis in kindreds with a restricted definition including only confirmed high-grade dysplasia (HGD) or EAC. The Familial Barrett's Esophagus Consortium database was used to identify individuals with HGD and EAC. These individuals were subsequently split into three kindred groups: non-familial-a single affected family member, duplex-two affected family members, and multiplex-three or more affected family members. Age of cancer diagnosis and other risk factors were compared between individuals in these groups. The study included 441 non-familial, 46 duplex, and 13 multiplex individuals. There was a statistically significant difference for age of diagnosis for individuals in the multiplex families compared to the non-familial and duplex families (56.0 versus 64.3, 63.5; p = 0.049). There was no significant difference between demographic factors and other cancer risk factors between family types. The results of this study support a genetic basis for familial Barrett's associated neoplasia and evaluation of the genetic susceptibility to this disease should continue to focus on families with multiple (three or more) affected members.

Systematic review with meta-analysis: the effects of family history on the risk of Barrett's oesophagus and oesophageal adenocarcinoma

BACKGROUND

Current guidelines recommend different screening approaches for individuals with a family history of Barrett's oesophagus (BO) or oesophageal adenocarcinoma (OAC), varying from no screening to screening all individuals with a positive family history.

AIMS

To determine evidence-based risk estimates for individuals with a family history of BO or OAC METHODS: We systematically searched Pubmed, Embase and Cochrane Library until October 2020 to identify all studies that reported on the association between family history and the risk of BO and OAC. Pooled summary estimates of adjusted relative risks and prevalence of familial BO/OAC with 95% confidence intervals (CIs) were calculated using a random effects model.

RESULTS

Fourteen studies comprising 16 189 BO/OAC patients were analysed. Familial clustering was seen in 8.84% (95% CI: 5.54-13.82) and 4.37% (95% CI: 2.15-8.69) of patients with BO and OAC, respectively (nine studies). Screening first-degree relatives of BO patients had a diagnostic yield between 12% and 44% for BO (four studies). However, the yield for high-grade dysplasia and OAC was low (<2%). Individuals with a positive family history had a higher risk of having BO (aRR 3.26; 95% CI 1.43-7.40; I²  = 46%; three studies) and OAC (aRR 2.19; 95% CI 1.14-4.21; I²  = 48%; five studies) compared to individuals without a family history.

CONCLUSIONS

A verified family history of BO or OAC is a strong risk factor for both BO and OAC. A positive family history could be a clinically meaningful way to identify high-risk individuals who may benefit from early detection strategies.

Increased risk of Barrett's oesophagus and related neoplasia in individuals with a positive family history

BACKGROUND

Considering the poor prognosis of oesophageal adenocarcinoma (EAC), it is important to identify individuals at increased risk of developing EAC who may benefit from early detection and prevention strategies. We aimed to determine whether individuals with a positive family history of Barrett's oesophagus (BE) and EAC are at an increased risk of oesophageal neoplasia.

METHODS

In a multi-centre case-control study, BE patients with or without related oesophageal neoplasia and randomly selected population controls filled out a questionnaire to collect information on family history and other risk factors for BE and EAC. Positive family history was defined as having ≥1 first-degree relative with BE or EAC whose diagnosis was histologically confirmed in the Dutch nationwide histopathology database.

FINDINGS

We included 480 BE patients and 420 controls without BE who had a total of 6393 first-degree relatives. A pathologically confirmed positive family history was significantly higher in BE patients compared with controls (6.5% versus 0.9; p < 0.001). Positive family history was independently associated with an increased risk of BE (OR 5.04; 95% CI 1.45-17.58; p = 0.01) after adjusting for known risk factors, such as gastroesophageal reflux disease and body mass index, and family size.

INTERPRETATION

We found that familial clustering of BE and EAC is present in 6.5% of Dutch BE patients. Subjects with ≥1 first-degree relative with BE or EAC have a 5-fold increased risk of BE and EAC. These findings emphasize the importance of a detailed family history in patients with BE or EAC to identify individuals at increased risk who may benefit from early detection strategies to prevent EAC-related mortality.

Esophageal Cancer: An Updated Review

The incidence of esophageal cancer (EC) is on the rise. With the distinct subtypes of adenocarcinoma and squamous cell carcinoma comes specific risk factors, and as a result, people of certain regions of the world can be more prone to a subtype. For example, squamous cell carcinoma of the esophagus has the highest incidence in eastern Africa and eastern Asia, with smoking being a major risk factor, whereas adenocarcinoma is more prevalent in North America and western Europe, with gastroesophageal reflux disease being a leading risk factor. With that being said, adenocarcinoma and squamous cell carcinoma have similar and unfortunately poor survival rates, partly because EC is prone to early metastasis given that the esophagus does not have a serosa, as well as the superficial nature of its lymphatics compared with the rest of the gastrointestinal tract. This makes early detection of the utmost importance, and certain patients have been shown to have the benefit of screening/surveillance endoscopies, including those with Barrett's esophagus, lye-induced/caustic strictures, tylosis, and Peutz-Jeghers syndrome. Until treatments significantly improve, identifying EC at the earliest stage will have the best success for patient outcomes, and further elucidation of its pathogenesis and risk factors may lead to identifying other high-risk groups that should be screened.

Esophagus and Gastrointestinal Junction Tumors

Esophageal squamous cell carcinoma and adenocarcinoma account for 95% of all esophageal malignancies. The rates of esophageal adenocarcinoma have increased in Western countries, making it the predominant type of esophageal cancer. Treatment of both types of cancer has transformed to a more minimally invasive approach, with endoscopic methods being used for superficial cancers and more frequent use of video-assisted and laparoscopic modalities for locally advanced tumors. The current National Comprehensive Cancer Network guidelines advocate a trimodal approach to treatment, with neoadjuvant chemoradiation and surgery for locally advanced cancers.

Germline variant in MSX1 identified in a Dutch family with clustering of Barrett's esophagus and esophageal adenocarcinoma

The vast majority of esophageal adenocarcinoma cases are sporadic and caused by somatic mutations. However, over the last decades several families have been identified with clustering of Barrett’s esophagus and esophageal adenocarcinoma. This observation suggests that one or more hereditary factors may play a role in the initiation of Barrett’s esophagus and esophageal adenocarcinoma in these families. A Dutch family with clustering of Barrett’s esophagus and esophageal adenocarcinoma was identified. Normal DNA obtained from the proband diagnosed with Barrett’s esophagus was analyzed with SNP array and exome sequencing. A custom-made panel consisting of potential germline variants was verified in the normal DNA of the affected family members. In addition, the respective tumors were analyzed for somatic loss of the wild type allele or the presence of an inactivating somatic mutation in the wild type allele. Exome sequencing revealed 244 candidate variants in the normal DNA of the proband, of which 212 variants were verified successfully. After the normal DNA of the affected family members was analyzed for the presence of the 212 potential germline variants and subsequently the respective tumors, only one potential germline variant in MSX1 (chr4: 4861985 T > G, c.359T > G, p.V120G, NM_002448) showed loss of the wild type allele in the tumor DNAs of the affected family members. A germline variant in MSX1 was identified in a Dutch family with clustering of Barrett’s esophagus and esophageal adenocarcinoma. This finding indicates that the germline defect in MSX1 may be associated with Barrett’s esophagus and cancer in this particular family.

Association of sporadic and familial Barrett's esophagus with breast cancer

Barrett's esophagus (BE) is the only known precursor to esophageal adenocarcinoma (EAC). Based on striking aggregation of breast cancer and BE/EAC within families as well as shared risk factors and molecular mechanisms of carcinogenesis, we hypothesized that BE may be associated with breast cancer. Pedigree analysis of families identified prospectively at multiple academic centers as part of the Familial Barrett's Esophagus Consortium (FBEC) was reviewed and families with aggregation of BE/EAC and breast cancer are reported. Additionally, using a matched case-control study design, we compared newly diagnosed BE cases in Caucasian females with breast cancer (cases) to Caucasian females without breast cancer (controls) who had undergone upper endoscopy (EGD). Two familial pedigrees, meeting a stringent inclusion criterion, manifested familial aggregation of BE/EAC and breast cancer in an autosomal dominant inheritance pattern with incomplete penetrance. From January 2008 to October 2016, 2812 breast cancer patient charts were identified, of which 213 were Caucasian females who underwent EGD. Six of 213 (2.82%) patients with breast cancer had pathology-confirmed BE, compared to 1 of 241 (0.41%) controls (P-value < 0.05). Selected families with BE/EAC show segregation of breast cancer. A breast cancer diagnosis is marginally associated with BE. We postulate a common susceptibility between BE/EAC and breast cancer.

Complex Segregation Analysis Provides Evidence for Autosomal Dominant Transmission in the Chinese Han Families with Ankylosing Spondylitis

Introduction

Familial aggregation of ankylosing spondylitis (AS) has been frequently noticed. However, the mode of inheritance in AS remains poorly understood. Our aim was to determine the mode of inheritance best fitting the observed transmission pattern of AS families.

Methods

Families with 5 or more AS patients diagnosed with 1984 modified New York criteria were recruited. We performed complex segregation analysis for a binary trait in regressive multivariate logistic models. The inheritance models, including sporadic, major gene, environmental, general, and other 9 models, were compared by likelihood ratio tests and Akaike's Information Criterion.

Results

This research included 9 Chinese Han AS families with a total number of 315 persons, including 74 patients. First, familial association was determined. Sporadic with familial association model was rejected when compared with either the general model or the homogeneous general model (p < 0.001). The environmental model was also rejected when compared with general models (p < 0.02). Mendelian dominate mode fitted best in 5 AS families, while Tau AB free model best explained the mode of inheritance in these AS families.

Conclusion

This study provided evidence in support of Mendelian dominant mode and firstly discovered a non-Mendelian mode called tau AB free inheritance mode in AS.

The Evolving Genomic Landscape of Barrett's Esophagus and Esophageal Adenocarcinoma

We have recently gained unprecedented insight into genetic factors that determine risk for Barrett's esophagus (BE) and progression to esophageal adenocarcinoma (EA). Next-generation sequencing technologies have allowed us to identify somatic mutations that initiate BE and track genetic changes during development of tumors and invasive cancer. These technologies led to identification of mechanisms of tumorigenesis that challenge the current multistep model of progression to EA. Newer, cost-effective technologies create opportunities to rapidly translate the analysis of DNA into tools that can identify patients with BE at high risk for cancer, detect dysplastic lesions more reliably, and uncover mechanisms of carcinogenesis.

Association Between Germline Mutation in VSIG10L and Familial Barrett Neoplasia

Importance

Esophageal adenocarcinoma and its precursor lesion Barrett esophagus have seen a dramatic increase in incidence over the past 4 decades yet marked genetic heterogeneity of this disease has precluded advances in understanding its pathogenesis and improving treatment.

Objective

To identify novel disease susceptibility variants in a familial syndrome of esophageal adenocarcinoma and Barrett esophagus, termed familial Barrett esophagus, by using high-throughput sequencing in affected individuals from a large, multigenerational family.

Design, Setting, and Participants

We performed whole exome sequencing (WES) from peripheral lymphocyte DNA on 4 distant relatives from our multiplex, multigenerational familial Barrett esophagus family to identify candidate disease susceptibility variants. Gene variants were filtered, verified, and segregation analysis performed to identify a single candidate variant. Gene expression analysis was done with both quantitative real-time polymerase chain reaction and in situ RNA hybridization. A 3-dimensional organotypic cell culture model of esophageal maturation was utilized to determine the phenotypic effects of our gene variant. We used electron microscopy on esophageal mucosa from an affected family member carrying the gene variant to assess ultrastructural changes.

Main Outcomes and Measures

Identification of a novel, germline disease susceptibility variant in a previously uncharacterized gene.

Results

A multiplex, multigenerational family with 14 members affected (3 members with esophageal adenocarcinoma and 11 with Barrett esophagus) was identified, and whole-exome sequencing identified a germline mutation (S631G) at a highly conserved serine residue in the uncharacterized gene VSIG10L that segregated in affected members. Transfection of S631G variant into a 3-dimensional organotypic culture model of normal esophageal squamous cells dramatically inhibited epithelial maturation compared with the wild-type. VSIG10L exhibited high expression in normal squamous esophagus with marked loss of expression in Barrett-associated lesions. Electron microscopy of squamous esophageal mucosa harboring the S631G variant revealed dilated intercellular spaces and reduced desmosomes.

Conclusions and Relevance

This study presents VSIG10L as a candidate familial Barrett esophagus susceptibility gene, with a putative role in maintaining normal esophageal homeostasis. Further research assessing VSIG10L function may reveal pathways important for esophageal maturation and the pathogenesis of Barrett esophagus and esophageal adenocarcinoma.

Common Variants Confer Susceptibility to Barrett's Esophagus: Insights from the First Genome-Wide Association Studies

Eight loci have been identified by the two genome-wide association studies of Barrett's esophagus that have been conducted to date. Esophageal adenocarcinoma cases were included in the second study following evidence that predisposing genetic variants for this cancer overlap with those for Barrett's esophagus. Genes with roles in embryonic development of the foregut are adjacent to 6 of the loci identified (FOXF1, BARX1, FOXP1, GDF7, TBX5, and ALDH1A2). An additional locus maps to a gene with known oncogenic potential (CREB-regulated transcription coactivator 1), but expression quantitative trait data implicates yet another gene involved in esophageal development (PBX4). These results strongly support a model whereby dysregulation of genes involved in esophageal and thoracic development increases susceptibility to Barrett's esophagus and esophageal adenocarcinoma, probably by reducing anatomical antireflux mechanisms. An additional signal at 6p21 in the major histocompatibility complex also reinforces evidence that immune and inflammatory response to reflux is involved in the development of both diseases. All of the variants identified are intronic or intergenic rather than coding and are presumed to be or to mark regulatory variants. As with genome-wide association studies of other diseases, the functional variants at each locus are yet to be identified and the genes affected need confirming. In this chapter as well as discussing the biology behind each genome-wide association signal, we review the requirements for successfully conducting genome-wide association studies and discuss how progress in understanding the genetic variants that contribute to Barrett's esophagus/esophageal adenocarcinoma susceptibility compares to other cancers.

Segregation Analysis Using the Unified Model

Segregation analysis is a basic tool in human genetics. It is a statistical method to determine if a trait, continuous or binary, has a transmission pattern in pedigrees that is consistent with Mendelian segregation. Major locus segregation is combined together with multifactorial/polygenic inheritance in the unified model. Segregation analysis as a procedure to identify the presence of segregation at a major Mendelian locus, with/without multifactorial inheritance, is introduced in this chapter. It is illustrated with the program SEGREG in the Statistical Analysis for Genetic Epidemiology (S.A.G.E.) package, which can use either regressive models or the finite polygenic mixed model to incorporate the multifactorial/polygenic component.

The Genetics of Barrett's Esophagus: A Familial and Population-Based Perspective

Barrett's esophagus (BE) is intestinal metaplasia of the lower esophagus and a precursor lesion for esophageal adenocarcinoma (EAC). Both are important health issues as they have rising incidences in the Western world. Improving the management of BE relies on understanding the underlying biology of this disease, but the exact biological mechanisms have been difficult to determine. BE is generally thought to be an acquired condition that develops secondarily to chronic gastroesophageal reflux. However, multiple reports of familial clustering of patients with BE and/or EAC suggest a possible inherited predisposition to BE may be driving this condition, at least in a subset of patients. Identifying the genetic variants that predispose to BE in these families would open up the possibility for blood-based screening tests that could inform decision-making in regard to surveillance strategies, particularly for relatives of patients with BE and/or EAC. Perhaps more importantly, understanding the genetic mechanisms that predispose to BE may provide valuable insights into the biology of this condition and potentially identify novel targets for therapeutic intervention. Here we review the current evidence for a genetic predisposition to BE and discuss the potential implications of these findings.

Linkage and related analyses of Barrett's esophagus and its associated adenocarcinomas

Background

Familial aggregation and segregation analysis studies have provided evidence of a genetic basis for esophageal adenocarcinoma (EAC) and its premalignant precursor, Barrett's esophagus (BE). We aim to demonstrate the utility of linkage analysis to identify the genomic regions that might contain the genetic variants that predispose individuals to this complex trait (BE and EAC).

Methods

We genotyped 144 individuals in 42 multiplex pedigrees chosen from 1000 singly ascertained BE/EAC pedigrees, and performed both model‐based and model‐free linkage analyses, using S.A.G.E. and other software. Segregation models were fitted, from the data on both the 42 pedigrees and the 1000 pedigrees, to determine parameters for performing model‐based linkage analysis. Model‐based and model‐free linkage analyses were conducted in two sets of pedigrees: the 42 pedigrees and a subset of 18 pedigrees with female affected members that are expected to be more genetically homogeneous. Genome‐wide associations were also tested in these families.

Results

Linkage analyses on the 42 pedigrees identified several regions consistently suggestive of linkage by different linkage analysis methods on chromosomes 2q31, 12q23, and 4p14. A linkage on 15q26 is the only consistent linkage region identified in the 18 female‐affected pedigrees, in which the linkage signal is higher than in the 42 pedigrees. Other tentative linkage signals are also reported.

Conclusion

Our linkage study of BE/EAC pedigrees identified linkage regions on chromosomes 2, 4, 12, and 15, with some reported associations located within our linkage peaks. Our linkage results can help prioritize association tests to delineate the genetic determinants underlying susceptibility to BE and EAC.

Predictors of Progression to High-Grade Dysplasia or Adenocarcinoma in Barrett's Esophagus

The prevalence of esophageal adenocarcinoma is increasing dramatically. Barrett's esophagus remains the most well-established risk factor for the development of esophageal adenocarcinoma. There are multiple clinical, endoscopic, and pathologic factors that increase the risk of neoplastic progression to high-grade dysplasia or esophageal adenocarcinoma in Barrett's esophagus. This article reviews both risk and protective factors for neoplastic progression in patients with Barrett's esophagus.

Barrett's oesophagus: frequency and prediction of dysplasia and cancer

The incidence of oesophageal adenocarcinoma is continuing to increase at an alarming rate in the Western world today. Barrett's oesophagus is a clearly recognized risk factor for the development of oesophageal adenocarcinoma, but the overwhelming majority of patients with Barrett's oesophagus will never develop oesophageal cancer. A number of endoscopic, histologic and epidemiologic risk factors identify Barrett's oesophagus patients at increased risk for progression to high-grade dysplasia and oesophageal adenocarcinoma. Endoscopic factors include segment length, mucosal abnormalities as seemingly trivial as oesophagitis and the 12 to 6 o'clock hemisphere of the oesophagus. Both intestinal metaplasia and low grade dysplasia, the latter only if confirmed by a pathologist with expertise in Barrett's oesophagus pathologic interpretation are the histologic risk factors for progression. Epidemiologic risk factors include ageing, male gender, obesity, and smoking. Factors that may protect against the development of adenocarcinoma include a diet rich in fruits and vegetables, and the use of proton pump inhibitors, aspirin/NSAIDs and statins.

Familial clustering of Barrett's esophagus and esophageal adenocarcinoma in a European cohort

BACKGROUND & AIMS

Up to 7% of cases of Barrett's esophagus (BE) or esophageal adenocarcinoma (EAC) in the United States occur in family clusters. We identified first-degree and second-degree relatives of patients with BE and EAC to determine the extent of familial clustering in a European cohort and studied differences between familial and nonfamilial cases.

METHODS

A questionnaire was sent to all patients diagnosed with BE or EAC from 2000-2011 at 3 hospitals in the Netherlands (n = 838). Diagnoses of affected relatives were confirmed by using the Dutch Pathology Registry. Familial statuses of BE were defined as definitive (≥1 first-degree or second-degree relative with BE or EAC), possible (≥1 reported relative with BE or esophageal cancer without histologic confirmation), unlikely (no family history), or unknown.

RESULTS

A total of 603 patients with BE or EAC (71%) responded and were included in the analysis. Familial BE was definitive for 7% of cases (n = 39, 10% of first-degree relatives affected), possible for 6% (n = 36), unlikely for 49% (n = 297), and unknown for 38% (n = 231). Definitive cases of familial BE were younger at onset of heartburn and EAC diagnosis; their first-degree relatives more frequently had reflux symptoms and a prior upper endoscopy, compared with unlikely cases of familial BE.

CONCLUSIONS

In a database analysis of patients diagnosed with BE or EAC in the Netherlands, 7% of cases of BE and EAC were familial. These cases have a younger average age of onset of reflux symptoms and diagnosis of EAC than unlikely familial cases. These findings may indicate that genetic factors contribute to BE susceptibility, with a possible central role of gastroesophageal reflux.

Molecular epidemiology of and genetic susceptibility to esophageal cancer

The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on clonal evolution in Barrett's carcinogenesis; biomarkers for early detection of esophageal cancer; the role of the methylguanine methyl transferase biomarker in the management of adenocarcinoma; and the discovery of high-risk genes in families.

Hereditary Factors in Esophageal Adenocarcinoma

BACKGROUND

The vast majority of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC) cases are sporadic and caused by somatic mutations. However, over the last decades several families have been identified with clustering of EAC. Here, we review data from the published literature in order to address the current knowledge on familial EAC.

SUMMARY

Although familial EAC comprises a relatively small group of patients, it is a clinically relevant category due to the poor prognosis of this type of cancer. Efforts should be made to identify specific genetic risk factors for familial EAC to enable identification of relatives at risk, since endoscopic surveillance can diagnose preneoplastic or early neoplastic lesions leading to early treatment, with improved outcome.

KEY MESSAGE

Although familial EAC comprises a relatively small group of patients, this is a clinically relevant category due to the poor prognosis. Efforts should be made to identify specific genetic risk factors for familial EAC in order to facilitate the identification of other family members with a predisposition for this type of cancer.

PRACTICAL IMPLICATIONS

Approximately 7% of BE and EAC cases are considered familial. Age at diagnosis is generally lower for patients with familial EAC as compared to sporadic cases, while other known risk factors for EAC, such as male gender and Caucasian ethnicity, do not differ between the two groups. In several described families with clustering of EAC the pattern of inheritance seems to be consistent with a rare autosomal dominant genetic trait. However, some association has been found with (attenuated) familial adenomatous polyposis, mismatch repair deficiency and recently with the genes MSR1, ASCC1 and CTHRC1. Nevertheless, no specific genetic predisposition has yet been identified.

Barrett's oesophagus: epidemiology, cancer risk and implications for management

Although endoscopic surveillance of patients with Barrett's oesophagus has been widely implemented, its effectiveness is debateable. The recently reported low annual oesophageal adenocarcinoma risk in population studies, the failure to identify most Barrett's patients at risk of disease progression, the poor adherence to surveillance and biopsy protocols, and the significant risk of misclassification of dysplasia all tend to undermine the effectiveness of current management, in particular, endoscopic surveillance programmes, to prevent or improve the outcomes of patients with oesophageal adenocarcinoma. The ongoing increase in incidence of Barrett's oesophagus and consequent growth of the surveillance population, together with the associated discomfort and costs of endoscopic surveillance, demand improved techniques for accurately determining individual risk of oesophageal adenocarcinoma. More accurate techniques are needed to run efficient surveillance programmes in the coming decades. In this review, we will discuss the current knowledge on the epidemiology of Barrett's oesophagus, and the challenging epidemiological dilemmas that need to be addressed when assessing the current screening and surveillance strategies.

Segregation analysis of mandibular prognathism in Korean orthognathic surgery patients and their families

Objective:

To investigate the existence of genetic influences on the incidence of mandibular prognathism (MP) in Korean Class III patients.

Materials and Methods:

The probands consisted of 100 Class III patients with MP (51 men and 49 women; mean age, 22.1 ± 5.2 years; SNA, 81.2° ± 3.2°; SNB, 84.1° ± 3.9°) who underwent orthognathic surgery. Using three-generation pedigree charts, questionnaires, and clinical examinations, general information and information regarding MP for a total of 3777 relatives of the probands (1911 men and 1866 women) was ascertained. Familial correlations of MP between possible pairs in the pedigree were estimated. Heritability (h2) of MP under various models was estimated. Segregation analysis was conducted under the assumption of the nonpolygenic multivariate logistic model and finite polygenic mixed model. One-, two-, and three-susceptibility-type models were evaluated.

Results:

Among 3777 relatives, 199 (97 men and 102 women) were affected with MP (5.3%). Correlation coefficients of MP incidence in full siblings and in parent-offspring were .2003 and .2036, respectively (all P &lt; .001). The h2 of MP was estimated as 21.5% after adjusting for sex and founder effects. Two- and three–susceptibility-type models showed that the general model fit better than the other models. MP incidence did not have a major gene transmission model and was influenced by numerous minor effect genes and their additive effects.

Conclusion:

These results suggest that the inherited susceptibility to MP in Korean Class III patients might be due to the summation of minor effects from a variety of different genes and/or influence of environmental factors, rather than Mendelian transmission of major genes.

Common variants at the MHC locus and at chromosome 16q24.1 predispose to Barrett's esophagus

Barrett’s Esophagus is an increasingly common disease that is strongly associated with reflux of stomach acid and usually a hiatus hernia. Barrett’s Esophagus strongly predisposes to esophageal adenocarcinoma (EAC), a tumour with a very poor prognosis. We have undertaken the first genome-wide association study on Barrett’s Esophagus, comprising 1,852 UK cases and 5,172 UK controls in discovery and 5,986 cases and 12,825 controls in the replication. Two regions were associated with disease risk: chromosome 6p21, rs9257809 (P_combined=4.09×10⁻⁹, OR(95%CI) =1.21(1.13-1.28)) and chromosome 16q24, rs9936833 (P_combined=2.74×10⁻¹⁰, OR(95%CI) =1.14(1.10-1.19)). The top SNP on chromosome 6p21 is within the major histocompatibility complex, and the closest protein-coding gene to rs9936833 on chromosome 16q24 is FOXF1, which is implicated in esophageal development and structure. We found evidence that the genetic component of Barrett’s Esophagus is mediated by many common variants of small effect and that SNP alleles predisposing to obesity also increase risk for Barrett’s Esophagus.

Diagnosis and management of Barrett's esophagus

Barrett esophagus is characterized by the replacement of squamous mucosa in the esophagus by specialized intestinal metaplasia. Its clinical significance lies in it being the strongest risk factor for and known precursor for esophageal adenocarcinoma. Diagnosis requires endoscopic confirmation of columnar metaplasia in the distal esophagus and histologic confirmation of specialized intestinal metaplasia. Recommendations for the management of subjects diagnosed with Barrett esophagus include periodic endoscopic surveillance to detect the development of high-grade dysplasia or adenocarcinoma. Careful endoscopic evaluation with high-resolution endoscopy and endoscopic resection is recommended in the evaluation of subjects with high-grade dysplasia and early adenocarcinoma.

Diagnosis and management of Barrett's esophagus

Barrett esophagus is characterized by the replacement of squamous mucosa in the esophagus by specialized intestinal metaplasia. Its clinical significance lies in it being the strongest risk factor for and known precursor for esophageal adenocarcinoma. Diagnosis requires endoscopic confirmation of columnar metaplasia in the distal esophagus and histologic confirmation of specialized intestinal metaplasia. Recommendations for the management of subjects diagnosed with Barrett esophagus include periodic endoscopic surveillance to detect the development of high-grade dysplasia or adenocarcinoma. Careful endoscopic evaluation with high-resolution endoscopy and endoscopic resection is recommended in the evaluation of subjects with high-grade dysplasia and early adenocarcinoma.

Barrett's esophagus and esophageal cancer: an overview

Although esophageal cancer (EC) is the eighth most common cancer in several European countries, it is one of deadliest worldwide. The most frequent predisposing factor implicated in its development is Barrett's esophagus (BE), an acquired metaplastic transformation of the esophageal lining cells from normal squamous epithelium into specialised or intestinal-like columnar epithelium. The major risk factor for BE is gastroesophageal reflux disease. Although BE is in itself a benign and often asymptomatic disorder, its clinical importance stems from the recognition that it represents the main precursor lesion for the development of esophageal adenocarcinoma (AC), a tumor that is rapidly increasing especially in developed countries and is associated with a low survival rate. This paper provides an overview of the epidemiology and natural history of BE as well as of the possible pathogenetic mechanisms underlying the development of BE and its progressive transition to AC. New diagnostic tests are described, recommendations for screening and surveillance are provided and surgical and ablative procedures to treat dysplastic lesions and early neoplasia are discussed. Claimed chemopreventive agents and biomarkers that in the near future may help identify people with a higher risk of EC are also considered.

Segregation analysis using the unified model

Segregation analysis is a basic tool in human genetics. It is a statistical method to determine if a trait, continuous or binary, has a transmission pattern in pedigrees that is consistent with Mendelian segregation. Major locus segregation is combined together with multifactorial/polygenic inheritance in the unified model. Segregation analysis as a procedure to identify the presence of segregation at a major Mendelian locus, with/without multifactorial inheritance, is introduced in this chapter. It is illustrated with the program SEGREG in the Statistical Analysis for Genetic Epidemiology (S.A.G.E.) package, which can use either regressive models or the finite polygenic mixed model to incorporate the multifactorial/polygenic component.

Some capabilities for model-based and model-free linkage analysis using the program package S.A.G.E. (Statistical Analysis for Genetic Epidemiology)

For both model-free and model-based linkage analysis the S.A.G.E. (Statistical Analysis for Genetic Epidemiology) program package has some unique capabilities in analyzing both continuous traits and binary traits with variable age of onset. Here we highlight model-based linkage analysis of a quantitative trait (plasma dopamine β hydroxylase) that is known to be largely determined by monogenic inheritance, using a prior segregation analysis to produce the best fitting model for the trait. For a binary trait with variable age of onset (schizophrenia), we illustrate how using age of onset information to obtain a quantitative susceptibility trait leads to more statistically significant linkage signals, suggesting better power.

Variation in age at cancer diagnosis in familial versus nonfamilial Barrett's esophagus

BACKGROUND

Genetic influences may be discerned in families that have multiple affected members and may manifest as an earlier age of cancer diagnosis. In this study, we determine whether cancers develop at an earlier age in multiplex Familial Barrett's Esophagus (FBE) kindreds, defined by 3 or more members affected by Barrett's esophagus (BE) or esophageal adenocarcinoma (EAC).

METHODS

Information on BE/EAC risk factors and family history was collected from probands at eight tertiary care academic hospitals. Age of cancer diagnosis and other risk factors were compared between nonfamilial (no affected relatives), duplex (two affected relatives), and multiplex (three or more affected relatives) FBE kindreds.

RESULTS

The study included 830 nonfamilial, 274 duplex, and 41 multiplex FBE kindreds with 274, 133, and 43 EAC and 566, 288, and 103 BE cases, respectively. Multivariable mixed models adjusting for familial correlations showed that multiplex kindreds were associated with a younger age of cancer diagnosis (P = 0.0186). Median age of cancer diagnosis was significantly younger in multiplex compared with duplex and nonfamilial kindreds (57 vs. 62 vs. 63 years, respectively, P = 0.0448). Mean body mass index was significantly lower in multiplex kindreds (P = 0.0033), as was smoking (P < 0.0001), and reported regurgitation (P = 0.0014).

CONCLUSIONS

Members of multiplex FBE kindreds develop EAC at an earlier age compared with nonfamilial EAC cases. Multiplex kindreds do not have a higher proportion of common risk factors for EAC, suggesting that this aggregation might be related to a genetic factor.

IMPACT

These findings indicate that efforts to identify susceptibility genes for BE and EAC will need to focus on multiplex kindreds.

Prevalence of Barrett esophagus in first-degree relatives of patients with esophageal adenocarcinoma

AIM

The aim of this study is to determine the prevalence of Barrett esophagus (BE) in first-degree relatives of patients with esophageal adenocarcinoma (EAC) and Barrett high-grade dysplasia (HGD).

METHODS

After Institutional Review Board approval, first-degree relatives of patients with EAC/HGD underwent unsedated ultrathin transnasal endoscopy (UUTNE) with biopsy. BE was suspected if any salmon-colored epithelial tongues were seen above the gastroesophageal junction. A diagnosis of BE was made only if biopsy from these areas confirmed columnar-lined epithelium with intestinal metaplasia.

RESULTS

From 23 families, 47 first-degree relatives underwent ultrathin transnasal endoscopy and 1 patient underwent routine upper endoscopy with sedation as part of this study. The mean age of cases was 44.4 years. All patients tolerated the procedure well and there were no procedure-related complications. BE was suspected in 16 (34%) patients and confirmed in 13 of 16 (27.7%) patients. There were 4 long segments (>3 cm) and 9 short segments (<3 cm) of BE.

CONCLUSION

There is a significantly higher than expected prevalence of BE in first-degree relatives of patients with EAC/HGD. This should be taken in to consideration to develop further screening guidelines. Further work is needed to confirm these findings. Unsedated transnasal endoscopy is a safe and well-tolerated method for BE screening.

Hereditary gastrointestinal cancer syndromes

The rapid growth of molecular genetics and its attendant germline mutation discoveries has enabled identification of persons who are at an inordinately high cancer risk and, therefore, ideal candidates for prevention. However, one must fully appreciate the extensive genotypic and phenotypic heterogeneity that exists in hereditary cancer. Once the causative germline mutation has been identified in a patient, high-risk members of the family can be similarly tested and identified and provided highly targeted surveillance and management opportunities. DNA testing can change the individual's presumed risk status and affect decision making by patients and their physicians regarding surveillance and management. Our purpose is to describe familial/hereditary cancers of the gastrointestinal tract, including familial Barrett's esophagus, hereditary diffuse gastric cancer, gastrointestinal stromal tumors, familial adenomatous polyposis and desmoid tumors, Lynch syndrome, small bowel cancer, and familial pancreatic cancer. We use our discussion of Lynch syndrome as a model for diagnostic and clinical translation strategies for all hereditary gastrointestinal tract cancers, which clearly can then be extended to cancer of all anatomic sites. Highly pertinent questions from the patient's perspective include the following: What kind of counseling will be provided to a patient with a Lynch syndrome mutation, and should that counseling be mandatory? Does the proband have the responsibility to inform relatives about the familial mutation, even if the relatives do not want to know whether they carry it? Is the patient is responsible for notifying family members that a parent or sibling has Lynch syndrome? Can notification be forced and, if so, under what circumstances? These questions point out the need for criteria regarding which family members to inform and how to inform them.

Comparison of endoscopic and clinical characteristics of patients with familial and sporadic Barrett's esophagus

BACKGROUND

A proportion of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC) displays familial aggregation, known as familial Barrett's esophagus (FBE). Pedigrees and characteristics of EAC in these families have been previously described.

AIMS

We aimed to evaluate endoscopic and clinical characteristics of Barrett's esophagus in FBE.

METHODS

A cohort of 979 BE patients were retrospectively evaluated for FBE, defined as having a first-degree relative with BE or esophageal cancer, confirmed when possible by interview. FBE and sporadic BE were compared regarding demographic, clinical, and endoscopic characteristics. Potential FBE probands were contacted and interviewed to obtain full family pedigrees.

RESULTS

Of 603 BE probands (61.6% of total cohort) with a documented family history, 35 (5.8%) had FBE. There was no difference between FBE and non-FBE probands with regard to BE length (median: 3 cm, IQR 2-5 vs. 3 cm, IQR 1-6 cm, respectively; p = 0.78) or hiatal hernia size (p = 0.90). FBE probands were younger (mean, 58.4 vs. 63.8; p = 0.02) and had a significant association with less-advanced neoplasia (adjusted OR 0.41, 95% CI 0.19-0.90). There was no obvious association between FBE and other malignancies.

CONCLUSIONS

There were no differences in endoscopic characteristics between FBE and non-FBE probands. While FBE patients were younger and had less-advanced neoplasia, we speculate that these findings may have been the result of more aggressive screening due to the family history. Further studies are warranted to determine whether familial clustering is due to genetic predisposition to development of BE or to risk of neoplastic progression.

Barrett's esophagus

Barrett's esophagus is an acquired metaplastic abnormality in which the normal stratified squamous epithelium lining of the esophagus is replaced by an intestinal-like columnar epithelium. While in itself a benign and asymptomatic disorder, the clinical importance of this relatively common condition relates to its role as a precursor lesion to esophageal adenocarcinoma, the incidence of which has dramatically increased in Western populations in recent years. Although known to arise as a consequence of chronic gastroesophageal reflux, the cellular and molecular mechanisms underlying development Barrett's esophagus and its progression to cancer remain unclear.