Contribution of Mendelian disorders to common chronic disease: Opportunities for recognition, intervention, and prevention

Ethical considerations of preconception and prenatal gene modification in the embryo and fetus

The National Academies of Sciences and Medicine 2020 consensus statement advocates the reinstatement of research in preconception heritable human genome editing (HHGE), despite the ethical concerns that have been voiced about interventions in the germline, and outlines criteria for its eventual clinical application to address monogenic disorders. However, the statement does not give adequate consideration to alternative technologies. Importantly, it omits comparison to fetal gene therapy (FGT), which involves gene modification applied prenatally to the developing fetus and which is better researched and less ethically contentious. While both technologies are applicable to the same monogenic diseases causing significant prenatal or early childhood morbidity, the benefits and risks of HHGE are distinct from FGT though there are important overlaps. FGT has the current advantage of a wealth of robust preclinical data, while HHGE is nascent technology and its feasibility for specific diseases still requires scientific proof. The ethical concerns surrounding each are unique and deserving of further discussion, as there are compelling arguments supporting research and eventual clinical translation of both technologies. In this Opinion, we consider HHGE and FGT through technical and ethical lenses, applying common ethical principles to provide a sense of their feasibility and acceptability. Currently, FGT is in a more advanced position for clinical translation and may be less ethically contentious than HHGE, so it deserves to be considered as an alternative therapy in further discussions on HHGE implementation.

Genetic Burden Contributing to Extremely Low or High Bone Mineral Density in a Senior Male Population From the Osteoporotic Fractures in Men Study (MrOS)

Worldwide, one in five men aged over 50 years will experience osteoporosis or a clinical bone fracture, with a greater fracture-related mortality rate than women. However, the genetic etiology of osteoporosis in men is still poorly understood. We aimed to identify the genetic variants and candidate genes associated with extremely low or high BMD for a better understanding of the biology underlying low bone density that may point to potential therapeutic targets for increasing bone mass. Subjects from the Osteoporotic Fractures in Men Study (MrOS) cohort were evaluated by age and BMI-adjusted total hip BMD. Those with BMD values 3 SDs away from the mean were selected and the remaining individuals whose adjusted BMD ranked at the highest or lowest 100 were included. Men with the lowest adjusted BMD (N = 98) and highest adjusted BMD (N = 110) were chosen for exome sequencing. Controls (N = 82) were men of Northern and Western European descent from the US Utah population of the 1000 Genomes Project. Fisher's exact test was performed to compare low- or high-BMD subjects with controls for single-gene associations. Additionally, sets of candidate genes causative of heritable disorders of connective tissue, including osteogenesis imperfecta (OI) and Ehlers-Danlos syndrome (EDS), were grouped for multigene and mutation burden analyses. No single-gene associations with rare variants were found for either the low BMD group (33 genes) or high BMD group (18 genes). In the group of OI genes, we detected a significant threefold increased accumulation of rare variants in low-BMD subjects compared with controls (p = 0.009). Additionally, genes associated with EDS had a twofold increased frequency in low-BMD subjects compared with controls (p = 0.03). These findings reveal a rare variant burden in OI and EDS disease genes at low BMD, which suggests a potential gene-panel approach to screen for multivariant associations in larger cohorts. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Metabolic pathways at the crossroads of diabetes and inborn errors

Research over the past two decades has led to advances in our understanding of the genetic and metabolic factors that underlie the pathogenesis of type 2 diabetes mellitus (T2DM). While T2DM is defined by its hallmark metabolic symptoms, the genetic risk factors for T2DM are more immune-related than metabolism-related, and the observed metabolic disease may be secondary to chronic inflammation. Regardless, these metabolic changes are not benign, as the accumulation of some metabolic intermediates serves to further drive the inflammation and cell stress, eventually leading to insulin resistance and ultimately to T2DM. Because many of the biochemical changes observed in the pre-diabetic state (i.e., ectopic lipid storage, increased acylcarnitines, increased branched-chain amino acids) are also observed in patients with rare inborn errors of fatty acid and amino acid metabolism, an interesting question is raised regarding whether isolated metabolic gene defects can confer an increased risk for T2DM. In this review, we attempt to address this question by summarizing the literature regarding the metabolic pathways at the crossroads of diabetes and inborn errors of metabolism. Studies using cell culture and animal models have revealed that, within a given pathway, disrupting some genes can lead to insulin resistance while for others there may be no effect or even improved insulin sensitivity. This differential response to ablating a single metabolic gene appears to be dependent upon the specific metabolic intermediates that accumulate and whether these intermediates subsequently activate inflammatory pathways. This highlights the need for future studies to determine whether certain inborn errors may confer increased risk for diabetes as the patients age.

Stratifying empiric risk of schizophrenia among first degree relatives using multiple predictors in two independent Indian samples

BACKGROUND

Schizophrenia (SZ) has an estimated heritability of 64-88%, with the higher values based on twin studies. Conventionally, family history of psychosis is the best individual-level predictor of risk, but reliable risk estimates are unavailable for Indian populations. Genetic, environmental, and epigenetic factors are equally important and should be considered when predicting risk in 'at risk' individuals.

OBJECTIVE

To estimate risk based on an Indian schizophrenia participant's family history combined with selected demographic factors.

METHODS

To incorporate variables in addition to family history, and to stratify risk, we constructed a regression equation that included demographic variables in addition to family history. The equation was tested in two independent Indian samples: (i) an initial sample of SZ participants (N=128) with one sibling or offspring; (ii) a second, independent sample consisting of multiply affected families (N=138 families, with two or more sibs/offspring affected with SZ).

RESULTS

The overall estimated risk was 4.31±0.27 (mean±standard deviation). There were 19 (14.8%) individuals in the high risk group, 75 (58.6%) in the moderate risk and 34 (26.6%) in the above average risk (in Sample A). In the validation sample, risks were distributed as: high (45%), moderate (38%) and above average (17%). Consistent risk estimates were obtained from both samples using the regression equation.

CONCLUSIONS

Familial risk can be combined with demographic factors to estimate risk for SZ in India. If replicated, the proposed stratification of risk may be easier and more realistic for family members.

Missed opportunities in primary care: the importance of identifying depression through screening, family history, and chronic disease management

This study explored the adequacy of depression screening in a community health center. The medical charts of individuals (N = 90) enrolled at a community health center were randomly selected, reviewed, and compared to current standard-of-care guidelines for four elements: family history, screening for depression, control of chronic illnesses, and missed opportunities for preventive care. Family history documentation collected by the providers was limited and 44.4% had no family history. There was no routine depression screening process, although 48.9% of the clients had red flags (warning signals) for depression. Laboratory values used for screening control of chronic disease in the medical records were: fasting glucose levels ⩽100 mg/dL (46%), total cholesterol levels ⩽200 mg/dL (38%), and blood pressure ⩽120/80 mmHg (23%). The results highlight the need to focus on depression screening as part of preventive care and the management of chronic disease in the primary care setting.

A compendium of inborn errors of metabolism mapped onto the human metabolic network

Inborn errors of metabolism (IEMs) are hereditary metabolic defects, which are encountered in almost all major metabolic pathways occurring in man. Many IEMs are screened for in neonates through metabolomic analysis of dried blood spot samples. To enable the mapping of these metabolomic data onto the published human metabolic reconstruction, we added missing reactions and pathways involved in acylcarnitine (AC) and fatty acid oxidation (FAO) metabolism. Using literary data, we reconstructed an AC/FAO module consisting of 352 reactions and 139 metabolites. When this module was combined with the human metabolic reconstruction, the synthesis of 39 acylcarnitines and 22 amino acids, which are routinely measured, was captured and 235 distinct IEMs could be mapped. We collected phenotypic and clinical features for each IEM enabling comprehensive classification. We found that carbohydrate, amino acid, and lipid metabolism were most affected by the IEMs, while the brain was the most commonly affected organ. Furthermore, we analyzed the IEMs in the context of metabolic network topology to gain insight into common features between metabolically connected IEMs. While many known examples were identified, we discovered some surprising IEM pairs that shared reactions as well as clinical features but not necessarily causal genes. Moreover, we could also re-confirm that acetyl-CoA acts as a central metabolite. This network based analysis leads to further insight of hot spots in human metabolism with respect to IEMs. The presented comprehensive knowledge base of IEMs will provide a valuable tool in studying metabolic changes involved in inherited metabolic diseases.

Hereditary breast and ovarian cancer and other hereditary syndromes: using technology to identify carriers

PURPOSE AND METHODS

Most patients who harbor a genetic mutation for hereditary breast cancer have not been identified, despite the availability of genetic testing. Developing an effective approach to the identification of high-risk individuals is the key to preventing and/or providing early diagnosis of cancer in this patient population. This educational review addresses these issues.

RESULTS AND DISCUSSION

Using data available on the internet, and making assumptions regarding the types and results of genetic testing, we have estimated the number of mutation carriers in the country and the number who have been tested and identified as such. Overall, our ability to fund and more effectively manage carriers is weak. A technological solution is discussed.

Population prevalence of familial cancer and common hereditary cancer syndromes. The 2005 California Health Interview Survey

PURPOSE

Family history guides cancer prevention and genetic testing. We sought to estimate the population prevalence of increased familial risk for breast, ovarian, endometrial, prostate, and colorectal cancers and hereditary cancer syndromes that include these cancers.

METHODS

Using the 2005 California Health Interview Survey data, a weak, moderate, or strong familial cancer risk was assigned to 33,187 respondents. Guidelines were applied to identify individuals with hereditary breast-ovarian cancer and hereditary nonpolyposis colon cancer.

RESULTS

Among respondents without a personal history of cancer, familial breast cancer was most prevalent; 7% had a moderate and 5% a strong familial risk. Older individuals and women were more likely to report family history of cancer. Generally, whites had the highest prevalence, and Asians and Latinos had the lowest prevalence. Among women without a personal history of breast or ovarian cancer, 2.5% met criteria for hereditary breast-ovarian cancer, and among individuals without a personal history of colorectal, endometrial or ovarian cancer, 1.1% met criteria for hereditary nonpolyposis colon cancer.

CONCLUSIONS

We provide population-based prevalence estimates for moderate and strong familial risk for five common cancers and hereditary breast-ovarian cancer and hereditary nonpolyposis colon cancer. Such estimates are helpful in planning and evaluation of genetic services and prevention programs, and assessment of cancer surveillance and prevention strategies.

Pernicious anemia - genetic insights

Pernicious anemia (PA) is a complex, autoimmune, multi-factorial disease. Rapid progress has been made in the understanding of susceptibility to a spectrum of other autoimmune diseases through genome wide association studies (GWAS). However, PA has been conspicuous by its absence from this work. Here, we examine the evidence that PA has a significant heritable component through epidemiological evidence and its co-occurrence with other autoimmune diseases. Further, we consider how knowledge of the genetic susceptibility to other autoimmune diseases may provide insight into the etiology of PA.

Family history in public health practice: a genomic tool for disease prevention and health promotion

Family history is a risk factor for many chronic diseases, including cancer, cardiovascular disease, and diabetes. Professional guidelines usually include family history to assess health risk, initiate interventions, and motivate behavioral changes. The advantages of family history over other genomic tools include a lower cost, greater acceptability, and a reflection of shared genetic and environmental factors. However, the utility of family history in public health has been poorly explored. To establish family history as a public health tool, it needs to be evaluated within the ACCE framework (analytical validity; clinical validity; clinical utility; and ethical, legal, and social issues). Currently, private and public organizations are developing tools to collect standardized family histories of many diseases. Their goal is to create family history tools that have decision support capabilities and are compatible with electronic health records. These advances will help realize the potential of family history as a public health tool.

Characteristics of health information gatherers, disseminators, and blockers within families at risk of hereditary cancer: implications for family health communication interventions

OBJECTIVES

Given the importance of the dissemination of accurate family history to assess disease risk, we characterized the gatherers, disseminators, and blockers of health information within families at high genetic risk of cancer.

METHODS

A total of 5466 personal network members of 183 female participants of the Breast Imaging Study from 124 families with known mutations in the BRCA1/2 genes (associated with high risk of breast, ovarian, and other types of cancer) were identified by using the Colored Eco-Genetic Relationship Map (CEGRM). Hierarchical nonlinear models were fitted to characterize information gatherers, disseminators, and blockers.

RESULTS

Gatherers of information were more often female (P<.001), parents (P<.001), and emotional support providers (P<.001). Disseminators were more likely female first- and second-degree relatives (both P<.001), family members in the older or same generation as the participant (P<.001), those with a cancer history (P<.001), and providers of emotional (P<.001) or tangible support (P<.001). Blockers tended to be spouses or partners (P<.001) and male, first-degree relatives (P<.001).

CONCLUSIONS

Our results provide insight into which family members may, within a family-based intervention, effectively gather family risk information, disseminate information, and encourage discussions regarding shared family risk.

General practitioners' attitudes to assessment of genetic risk of common disorders in routine primary care

In 2003, the UK Department of Health set out the genetics white paper, a plan for action and investment with particular emphasis on integration of genetic health care into primary care. Since the delivery of the genetics white paper, there has been little exploration of UK primary care doctors' attitudes towards extending their role to include provision of routine genetics services. We explored explore general practitioners' (GPs) attitudes towards provision of genetic health care including routine family history screening and familial risk assessment for common disorders in primary care using a quantitative, evaluative postal survey. Only 25% (797 of 3160) of the GPs returned a completed questionnaire. Although 32% of GPs supported collection of family history information and 41.5% familial risk assessment, 18% were not willing to offer these services even if training is provided. Of the GPs, 50% stated they recognized when referral to genetics services is appropriate, although 43% felt unprepared to collect family history or assess familial risk. Lack of training within the last 3 years was a significant predictor of feeling unprepared to undertake these activities (OR = 2.53,p = 0.012). A substantial group of GPs remain unprepared or unwilling to provide genetic health care. GPs' attitudes to delivery of genetic health care are significantly influenced by factors such as a lack of evidence of the direct benefits to patients, local guidelines and specialist services. These factors need addressing if delivery of genetic health care is to be incorporated into routine primary care.

Are electronic health records ready for genomic medicine?

PURPOSE

The goal of this project was to assess genetic/genomic content in electronic health records.

METHODS

Semistructured interviews were conducted with key informants. Questions addressed documentation, organization, display, decision support and security of family history and genetic test information, and challenges and opportunities relating to integrating genetic/genomics content in electronic health records.

RESULTS

There were 56 participants: 10 electronic health record specialists, 18 primary care clinicians, 16 medical geneticists, and 12 genetic counselors. Few clinicians felt their electronic record met their current genetic/genomic medicine needs. Barriers to integration were mostly related to problems with family history data collection, documentation, and organization. Lack of demand for genetics content and privacy concerns were also mentioned as challenges. Data elements and functionality requirements that clinicians see include: pedigree drawing; clinical decision support for familial risk assessment and genetic testing indications; a patient portal for patient-entered data; and standards for data elements, terminology, structure, interoperability, and clinical decision support rules. Although most said that there is little impact of genetics/genomics on electronic records today, many stated genetics/genomics would be a driver of content in the next 5-10 years.

CONCLUSIONS

Electronic health records have the potential to enable clinical integration of genetic/genomic medicine and improve delivery of personalized health care; however, structured and standardized data elements and functionality requirements are needed.

Rare association of Turner syndrome with neurofibromatosis type 1 and tuberous sclerosis complex

We report a rare association of Turner syndrome with both Neurofibromatosis type I and Tuberous Sclerosis. The patient had XOkaryotype with Turners stigmata and also had features of Neurofibromatosis 1 in the form of significant café-au-lait spots and Plexiform neurofibroma along with typical features of Tuberous Sclerosis complex. Pedigree analysis revealed that the elder brother of the proband in the family also suffered from Tuberous Sclerosis without the manifestation of Neurofibromatosis or any other genetic disorders. We hypothesize that these associations could be due to new independent mutations and also increased maternal and paternal age in a pre-disposition of Turner syndrome.

An overview of the genetic dissection of complex traits

Thanks to the recent revolutionary genomic advances such as the International HapMap consortium, resolution of the genetic architecture of common complex traits is beginning to look hopeful. While demonstrating the feasibility of genome-wide association (GWA) studies, the pathbreaking Wellcome Trust Case Control Consortium (WTCCC) study also serves to underscore the critical importance of very large sample sizes and draws attention to potential problems, which need to be addressed as part of the study design. Even the large WTCCC study had vastly inadequate power for several of the associations reported (and confirmed) and, therefore, most of the regions harboring relevant associations may not be identified anytime soon. This chapter provides an overview of some of the key developments in the methodological approaches to genetic dissection of common complex traits. Constrained Bayesian networks are suggested as especially useful for analysis of pathway-based SNPs. Likewise, composite likelihood is suggested as a promising method for modeling complex systems. It discusses the key steps in a study design, with an emphasis on GWA studies. Potential limitations highlighted by the WTCCC GWA study are discussed, including problems associated with massive genotype imputation, analysis of pooled national samples, shared controls, and the critical role of interactions. GWA studies clearly need massive sample sizes that are only possible through genuine collaborations. After all, for common complex traits, the question is not whether we can find some pieces of the puzzle, but how large and what kind of a sample we need to (nearly) solve the genetic puzzle.

Is family history a useful tool for detecting children at risk for diabetes and cardiovascular diseases? A public health perspective

Several studies indicate that the risk for type 2 diabetes or cardiovascular disease is detectable in childhood, although these disorders may not emerge until adulthood. In addition, type 2 diabetes and cardiovascular disease seem to share risk factors, including obesity and dyslipidemia, and might even share etiology, which has important implications for screening and prevention strategies for both diseases. Primary prevention, in particular, has gained importance because the results of major randomized, controlled trials strongly suggest that, at least in high-risk adult groups, type 2 diabetes can be prevented or delayed. Furthermore, some intervention studies indicate that the risk factors for diabetes and cardiovascular disease can be reduced in children. A simple way to detect risk for either diabetes or cardiovascular disease is to examine the family history. Numerous studies have shown that adults who have 1 or more first- or second-degree relatives affected with diabetes or cardiovascular disease are at high risk of having or developing these diseases. Currently, there are no overall screening strategies recommended for either diabetes or cardiovascular disease among children and adolescents. The evidence is strong, however, that youth with a positive family history already show signs of increased risk for these conditions. Family history can be part of the approach to screening for children at risk of diabetes and cardiovascular disease and should be part of prevention campaigns aimed at reducing the burden of these diseases and their risk factors in children.

Familial testicular cancer: interest in genetic testing among high-risk family members

PURPOSE

This study is part of an ongoing National Cancer Institute multidisciplinary, etiologically-focused, cross-sectional study of Familial Testicular Cancer (FTC). The current report targets interest in clinical genetic testing for susceptibility to FTC.

METHODS

Demographics, knowledge, health beliefs, and psychological and social factors were evaluated as covariates related to interest in genetic testing.

RESULTS

The majority (66%) of 229 participants (64 affected men, 66 unaffected men, and 99 women) from 47 multiple-case FTC families expressed interest in having a genetic test within 6 months, should such a test become available. Interest was similar among the three subgroups mentioned above. Worries about insurance discrimination based on genetic test results were associated with a significantly lower interest in testing. Alternatively, participants were more likely to be interested in genetic testing if they were younger and had higher levels of family support, a physician's recommendation supporting testing, cancer distress, and a need for information to inform the health care of their children.

CONCLUSIONS

This study reveals social and relationship factors that FTC survivors and their relatives considered important when contemplating the use of new genetic technologies. This is the first study describing hypothetical interest in genetic testing for familial testicular cancer.

Evaluation of common variants in the six known maturity-onset diabetes of the young (MODY) genes for association with type 2 diabetes

An important question in human genetics is the extent to which genes causing monogenic forms of disease harbor common variants that may contribute to the more typical form of that disease. We aimed to comprehensively evaluate the extent to which common variation in the six known maturity-onset diabetes of the young (MODY) genes, which cause a monogenic form of type 2 diabetes, is associated with type 2 diabetes. Specifically, we determined patterns of common sequence variation in the genes encoding Gck, Ipf1, Tcf2, and NeuroD1 (MODY2 and MODY4-MODY6, respectively), selected a comprehensive set of 107 tag single nucleotide polymorphisms (SNPs) that captured common variation, and genotyped each in 4,206 patients and control subjects from Sweden, Finland, and Canada (including family-based studies and unrelated case-control subjects). All SNPs with a nominal P value <0.1 for association to type 2 diabetes in this initial screen were then genotyped in an additional 4,470 subjects from North America and Poland. Of 30 nominally significant SNPs from the initial sample, 8 achieved consistent results in the replication sample. We found the strongest effect at rs757210 in intron 2 of TCF2, with corrected P values <0.01 for an odds ratio (OR) of 1.13. This association was observed again in an independent sample of 5,891 unrelated case and control subjects and 500 families from the U.K., for an overall OR of 1.12 and a P value <10(-6) in >15,000 samples. We combined these results with our previous studies on HNF4alpha and TCF1 and explicitly tested for gene-gene interactions among these variants and with several known type 2 diabetes susceptibility loci, and we found no genetic interactions between these six genes. We conclude that although rare variants in these six genes explain most cases of MODY, common variants in these same genes contribute very modestly, if at all, to the common form of type 2 diabetes.

Lost in transition: challenges in the expanding field of adult genetics

It is increasingly clear that medical genetics has broad relevance in adult clinical medicine. More adult patients with genetic conditions are being recognized, genetic testing for adult-onset genetic conditions is expanding, and children with genetic conditions are now more likely to survive to adulthood. While the number of patients who could benefit from medical genetic services increases, adult care providers are less well educated about clinical genetics and are not sufficiently prepared to meet the growing needs of this population. Genetics professionals may also be ill-suited for this challenge, since geneticists and genetic counselors have traditionally had greater experience in pediatric and prenatal settings. Communication between primary care physicians who treat adults and the genetics community is currently suboptimal and the identification and subsequent referral of adult patients for genetic services need improvement. Finally, published guidelines that address how to deliver genetic services to adult patients are unavailable for many genetic conditions. In this article we address the challenges of transitioning genetics services from traditional, and largely pediatric-based models to paradigms that can best address the needs of adult patients with genetic conditions. Potential solutions and the practicality of implementation of a team-based approach to adult genetic medicine, including the application of genetic counseling, are also discussed.

Heterozygosity for a Mendelian disorder as a risk factor for complex disease

While genetic diseases are generally classified as being either 'simple' monogenic or 'complex' polygenic, the distinction between Mendelian and complex disorders is becoming increasingly blurred. Mendelian disorders may demonstrate qualities more typical of multifactorial diseases through shared clinical presentations, the effect of genetic modifiers, moonlighting proteins, synergistic heterozygosity, disease manifestations in heterozygotes and situations where heterozygosity for a 'simple' disorder proves to be a risk factor for seemingly unrelated complex diseases. A recent example of the last instance is the observation that mutations in glucocerebrosidase, the enzyme deficient in Gaucher disease, may be a risk factor for the development of Parkinson disease and other synucleinopathies. Insights gleaned from the study of Mendelian disorders may ultimately lead to a better understanding of factors influencing complex diseases.

Genetic associations in preterm birth: a primer of marker selection, study design, and data analysis

Spontaneous preterm birth (PTB; delivery before 37 weeks gestation) is a primary risk factor for infant morbidity and mortality. The etiology is unclear, but there is evidence that there is a genetic predisposition to PTB. Armed with the suggestion of genetic risk factors and the failure to identify useful biomarkers, investigators are starting to actively pursue the role of genetic predisposition in PTB. Several studies have been done to date assessing the role of single gene variants. However, positive findings have failed to replicate. We argue that heterogeneity in study designs, definition of phenotype, single-nucleotide polymorphism (SNP) selection, population selection, and sample size makes data interpretation difficult in complex phenotypes such as PTB. In this review, we introduce general concepts of study designs in genetic epidemiology, selection of candidate genes and markers for analysis, and analytical methodologies. We also introduce how the concept of gene-gene interactions (biologic epistasis) and gene-environment interactions may affect the predisposition to PTB.

Analysis of association between maternal tumor necrosis factor-alpha promoter polymorphism (-308), tumor necrosis factor concentration, and preterm birth

OBJECTIVE

This study was undertaken to investigate the association of tumor necrosis factor-alpha (TNF-alpha) single nucleotide polymorphism (G-308>A) and risk of preterm birth by performing a systematic review and a meta-analysis of available studies. In addition, association between this variant and TNF-alpha concentration in amniotic fluid (AF) in preterm birth was also investigated.

STUDY DESIGN

Articles were chosen based on a Medline and EMBASE searches (1990-2005) with no language restrictions. An ongoing case-control study conducted in Nashville, TN, was also included. Articles evaluating the association between G-308>A and preterm birth were screened according to specific inclusion criteria. Meta-analysis was performed by using a random effect model. Association between maternal -308 genotype and AF-TNF-alpha concentration was determined by sandwich immunoassays.

RESULTS

Titles and abstracts of 6851 citations identified through the search were screened. Including our own study, a total of 7 studies were included for meta-analysis. Only 2 reported a statistically significant increased risk based on -308 genotype. Meta-analysis of the case-control studies on a pooled dataset (a total of 1846 subjects, 638 cases, and 1208 controls) showed no significant association between the -308 genotype and the risk of preterm birth (odds ratio [OR] 1.41; CI 0.90-2.19). A nonsignificant increase of AF TNF-alpha concentration was demonstrated with the GG genotype in cases compared with the presence of allele A.

CONCLUSION

Meta-analysis of available evidence documented no statistically significant association between a single nucleotide polymorphism in the TNF-alpha gene (G-308>A) and preterm birth. Analyses of AF-TNF-alpha concentration demonstrated no increase in TNF-alpha in the presence of the minor allele (A). These results suggest that this single nucleotide polymorphism does not independently associate strongly with preterm birth.

Population-based study of the prevalence of family history of cancer: implications for cancer screening and prevention

PURPOSE

Family history assessment is gaining importance as a potential public health tool to help determine susceptibility to common cancers. Population-based data on the prevalence of having a family history of common cancers are scant.

METHODS

We queried survey questions from the National Health Interview Survey, an annual nationwide survey of approximately 36,000 households in the United States, to determine the prevalence of persons reporting one or more first-degree relatives with breast, colorectal, lung, prostate, or ovarian cancer.

RESULTS

Breast cancer was the most common condition noted for family members (7.74% of respondents), followed by lung cancer (7.10%), colorectal cancer (4.96%), prostate cancer (4.68%), and ovarian cancer (1.79%). A family history of cancer was more commonly reported by older persons, whites, women, and high-income groups.

CONCLUSION

A substantial proportion of persons in the United States report having a close family member with cancer, and thus may be eligible for earlier or more aggressive cancer screening services.

Genetics of complex diseases

Approaches to the study of the genetic basis of common complex diseases and their clinical applications are considered. Monogenic Mendelian inheritance in such conditions is infrequent but its elucidation may help to detect pathogenic mechanisms in the more common variety of complex diseases. Involvement by multiple genes in complex diseases usually occurs but the isolation and identification of specific genes so far has been exceptional. The role of common polymorphisms as indicators of disease risk in various studies is discussed.

Decision making and decision support for hereditary breast-ovarian cancer susceptibility

Genetic testing for disease susceptibility has the potential to revolutionize health care by allowing for individually tailored disease prevention strategies. To achieve this promise, patients and physicians must use the information obtained through genetic testing to make medical decisions that are consistent with patient preferences and that lead to reduced disease morbidity and mortality. However, decisions associated with genetic testing can be complex. In this article, the authors review decision making associated with genetic testing and the medical management of hereditary breast-ovarian cancer susceptibility. They focus on decisions regarding BRCA1/2 testing and prophylactic surgery among BRCA1 and BRCA2 mutation carriers. They highlight the role of patient preferences and decision support in this population. The studies reviewed indicate that although patients' preferences do predict genetic testing and management decisions, other factors also influence their decision making. In particular, the authors discuss the role of anxiety and worry in relation to testing and surgery decisions.

Clinical application of genetic risk assessment strategies for coronary artery disease: genotypes, phenotypes, and family history

Individuals with genetic predisposition to atherosclerosis have an increased risk for developing coronary artery disease (CAD), especially at young ages. They may derive the greatest benefit from traditional preventive strategies and strategies targeting novel,emerging risk factors. Because CAD is a complex, multifactorial disorder, global risk assessment has been recognized as an effective approach in preventing CAD and its manifestations. The systematic collection and interpretation of family history information is currently the most appropriate screening approach to identify individuals with genetic susceptibility to CAD. Much of the familial aggregation of CAD might be explained by familial aggregation of established risk factors and emerging CAD risk factors. Tests to assess genetic risk for CAD are primarily biochemical analyses that measure the different pathways involved in development and progression of disease. Some of these can guide and explain responses to treatment.