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PubMed2006

A new definition of Genetic Counseling: National Society of Genetic Counselors' Task Force report.

The Genetic Counseling Definition Task Force of the National Society of Genetic Counselors (NSGC) developed the following definition of genetic counseling that was approved by the NSGC Board of Directors: Genetic counseling is the process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease. This process integrates the following: Interpretation of family and medical histories to assess the chance of disease occurrence or recurrence. Education about inheritance, testing, management, prevention, resources and research. Counseling to promote informed choices and adaptation to the risk or condition. The definition was approved after a peer review process with input from the NSGC membership, genetic professional organizations, the NSGC legal counsel, and leaders of several national genetic advocacy groups.

Genetic Counseling↗

PubMed2004

Characteristics of genetic epidemiology and genetic models for vitiligo.

BACKGROUND: Vitiligo occurs with a frequency of 0.1% to 2% in various populations and is classified into several subtypes by its clinical presentation. Although genetic factors are thought to be involved in the cause of vitiligo, the genetic models for different phenotypes of vitiligo are unknown. OBJECTIVE: Our purpose was to explore potential genetic models for different phenotypes of vitiligo and analyze genetic epidemiologic characteristics of vitiligo in a Chinese population. METHODS: Information from 2247 patients and members in their families was collected using a uniform questionnaire. Patients' clinical characteristics and their family history were analyzed using software. A complex segregation analysis was conducted to propose potential genetic models for vitiligo. RESULTS: Different subtypes of vitiligo had different ages of disease onset. In relatives of patients with vitiligo, the risk of developing vitiligo increased with increasing relatedness to the patients with vitiligo. A polygenic additive model was the best model for focal vitiligo, vitiligo vulgaris, acrofacial vitiligo, and segmental vitiligo with approximately 50% heritability in each. For universal vitiligo, the best model was an environmental model. CONCLUSION: This study indicated that different phenotypes of vitiligo had different pathogeneses and genetic backgrounds. Onset of vitiligo is possibly affected by both genetic backgrounds and common environmental factors.

Adolescent↗

PubMed1998

Genetic risks of intracytoplasmic sperm injection in the treatment of male infertility: recommendations for genetic counseling and screening.

OBJECTIVE: To review the most clinically significant genetic disorders associated with severe oligospermia and azoospermia in males, and to present recommendations for the genetic counseling and screening of infertile males and their partners before undertaking intracytoplasmic sperm injection (ICSI)-assisted reproduction. DESIGN: The literature on genetic disorders associated with severe oligospermia and azoospermia was reviewed, and the most recent outcome data from surveys of ICSI-derived offspring are presented. Studies related to this topic were identified through MEDLINE. RESULT(S): Genetic disorders are not infrequent causes of severe oligospermia and azoospermia in males undergoing ICSI-assisted reproduction. The application of ICSI in the treatment of oligospermic or azoospermic males may result in the transmission or de novo introduction of genetic mutations or chromosomal abnormalities in their offspring. Genetic counseling and appropriate screening of couples with male infertility should be performed before their undertaking ICSI-assisted reproduction. CONCLUSIONS: An understanding of the genetic risks and possible consequences that are inherent when ICSI is used to assist fertilization in couples with male infertility is necessary for clinicians and their patients.

Cytoplasm↗

PubMed2000

Ionizing radiation and genetic risks. XII. The concept of "potential recoverability correction factor" (PRCF) and its use for predicting the risk of radiation-inducible genetic disease in human live births.

Genetic risks of radiation exposure of humans are generally expressed as expected increases in the frequencies of genetic diseases over those that occur naturally in the population as a result of spontaneous mutations. Since human data on radiation-induced germ cell mutations and genetic diseases remain scanty, the rates derived from the induced frequencies of mutations in mouse genes are used for this purpose. Such an extrapolation from mouse data to the risk of genetic diseases will be valid only if the average rates of inducible mutations in human genes of interest and the average rates of induced mutations in mice are similar. Advances in knowledge of human genetic diseases and in molecular studies of radiation-induced mutations in experimental systems now question the validity of the above extrapolation. In fact, they (i) support the view that only in a limited number of genes in the human genome, induced mutations may be compatible with viability and hence recoverable in live births and (ii) suggest that the average rate of induced mutations in human genes of interest from the disease point of view will be lower than that assumed from mouse results. Since, at present, there is no alternative to the use of mouse data on induced mutation rates, there is a need to bridge the gap between these and the risk of potentially inducible genetic diseases in human live births. In this paper, we advance the concept of what we refer to here as "the potential recoverability correction factor" (PRCF) to bridge the above gap in risk estimation and present a method to estimate PRCF. In developing the concept of PRCF, we first used the available information on radiation-induced mutations recovered in experimental studies to define some criteria for assessing potential recoverability of induced mutations and then applied these to human genes on a gene-by-gene basis. The analysis permitted us to estimate unweighted PRCFs (i.e. the fraction of genes among the total studied that might contribute to recoverable induced mutations) and weighted PRCFs (i.e. PRCFs weighted by the incidences of the respective diseases). The estimates are: 0.15 (weighted) to 0.30 (unweighted) for autosomal dominant and X-linked diseases and 0.02 (weighted) to 0.09 (unweighted) for chronic multifactorial diseases. The PRCF calculations are unnecessary for autosomal recessive diseases since the risks projected for the first few generations even without using PRCFs are already very small. For congenital abnormalities, PRCFs cannot be reliably estimated. With the incorporation of PRCF into the equation used for predicting risk, the risk per unit dose becomes the product of four quantities (risk per unit dose=Px(1/DD)xMCxPRCF) where P is the baseline frequency of the genetic disease, 1/DD is the relative mutation risk per unit dose, MC is the mutation component and PRCF is the disease-class-specific potential recoverability correction factor instead of the first three (as has been the case thus far). Since PRCF is a fraction, it is obvious that the estimate of risk obtained with the revised risk equation will be smaller than previously calculated values.

Genetic Diseases, Inborn↗

PubMed2001

Genetic counselling and genetic screening for Alzheimer's disease and other dementias.

Genetic and nongenetic factors have been identified to have roles in the etiology of dementia. Etiologic heterogeneity and genetic heterogeneity are recognized, especially for Alzheimer's disease which is the most common form of dementia. Asymptomatic individuals are increasingly requesting genetic services such as genetic counselling, predictive testing and screening for genetic risk factors. This paper provides an overview of the current knowledge about genetic counselling and genetic screening for dementia as well as guidelines for the physician.

Aged↗

PubMed2001

A survey of genetic counselors' use of informed consent documents for prenatal genetic counseling sessions.

Thirty six members of the Prenatal Diagnosis Special Interest Group of the National Society of Genetic Counselors were interviewed about their use of informed consent documents for the genetic counseling component of their prenatal genetic counseling sessions and their perceptions of the utility and feasibility of such documents. Major findings include (1) None of the genetic counselors currently used a consent document describing the genetic counseling component of the session itself; (2) Only three participants stated that they had ever used an informed consent document for this component of the session; (3) They disagreed about the importance and usefulness of such a document; (4) There was variability in their reported likelihood of using a document if one were available; (5) There was a fair amount of agreement about the types of information to include on an informed consent document for genetic counseling; over half of the sample endorsed 8 of 10 topics; and (6) Participants identified 10 obstacles to using such a document. Recommendations for genetic counseling practice, policy, and research are given.

Attitude of Health Personnel↗

PubMed2002

The population genetics of host specificity: genetic differentiation in dove lice (Insecta: Phthiraptera).

Some species of parasites occur on a wide range of hosts while others are restricted to one or a few host species. The host specificity of a parasite species is determined, in part, by its ability to disperse between host species. Dispersal limitations can be studied by exploring the genetic structure of parasite populations both within a single species of host and across multiple host species. In this study we examined the genetic structure in the mitochondrial cytochrome oxidase I (COI) gene of two genera of lice (Insecta: Phthiraptera) occurring on multiple sympatric species of doves in southern North and Central America. One genus, Columbicola, is generally less host-specific than the other, Physconelloides. For both genera we identified substantial genetic differentiation between populations of conspecific lice on different host species, generally 10-20% sequence divergence. This level of divergence is in the range of that often observed between species of these two genera. We used nested clade analysis to explore fine scale genetic structure within species of these feather lice. We found that species of Physconelloides exhibited more genetic structure, both among hosts and among geographical localities, than did species of Columbicola. In many cases, single haplotypes within species of Columbicola are distributed on multiple host species. Thus, the population genetic structure of species of Physconelloides reveals evidence of geographical differentiation on top of high host species specificity. Underlying differences in dispersal biology probably explain the differences in population genetic structure that we observed between Columbicola and Physconelloides.

Animals↗

PubMed2004

From degeneration to genetic susceptibility, from eugenics to genethics, from Bezugsziffer to LOD score: the history of psychiatric genetics.

Reviewing the history of psychiatric genetics is a difficult task, since--in contrast to genetic research into most other disorders--it cannot simply be done by chronologically listing methodological achievements and major findings. Instead, it necessitates a comprehensive assessment of how the aetiological concept of mental disorders has developed since as early as the world of ancient Greece. Furthermore, it has to touch upon the sensitive issue of the eugenic movement that was closely linked to the study of heredity in mental disorders in the first half of the 20th century and, in Nazi Germany, led to the systematic mass murder of psychiatric patients. Finally, reviewing the scientific dimensions, history of psychiatric genetics is at the same time a walk through the history of complex genetics in general. In our review, we try to pay tribute to this complexity. We argue that psychiatric genetics has not only propelled our understanding of mental disorders but has significantly benefited genetic research into other complex disorders through the development of methodologically robust approaches (e.g., systematic phenotype characterisation, methods to control for ascertainment biases, age-correction). Given the recent reasons for new optimism, i.e., the identification of susceptibility genes for psychiatric phenotypes, a continued methodologically sound approach is needed more than ever to guarantee robust results. Finally, psychiatric genetic research should never again be performed in an environment void of ethical standards.

Ethics, Medical↗

PubMed2005

Integrative genetic analysis of transcription modules: towards filling the gap between genetic loci and inherited traits.

Genetic loci that regulate inherited traits are routinely identified using quantitative trait locus (QTL) mapping methods. However, the genotype-phenotype associations do not provide information on the gene expression program through which the genetic loci regulate the traits. Transcription modules are 'self-consistent regulatory units' and are closely related to the modular components of gene regulatory network [Ihmels, J., Friedlander, G., Bergmann, S., Sarig, O., Ziv, Y. and Barkai, N. (2002) Revealing modular organization in the yeast transcriptional network. Nat. Genet., 31, 370-377; Segal, E., Shapira, M., Regev, A., Pe'er, D., Botstein, D., Koller, D. and Friedman, N. (2003) Module networks: identifying regulatory modules and their condition-specific regulators from gene expression data. Nat. Genet., 34, 166-176]. We used genome-wide genotype and gene expression data of a genetic reference population that consists of mice of 32 recombinant inbred strains to identify the transcription modules and the genetic loci regulating them. Twenty-nine transcription modules defined by genetic variations were identified. Statistically significant associations between the transcription modules and 18 classical physiological and behavioral traits were found. Genome-wide interval mapping showed that major QTLs regulating the transcription modules are often co-localized with the QTLs regulating the associated classical traits. The association and the possible co-regulation of the classical trait and transcription module indicate that the transcription module may be involved in the gene pathways connecting the QTL and the classical trait. Our results show that a transcription module may associate with multiple seemingly unrelated classical traits and a classical trait may associate with different modules. Literature mining results provided strong independent evidences for the relations among genes of the transcription modules, genes in the regions of the QTLs regulating the transcription modules and the keywords representing the classical traits.

Animals↗

PubMed2003

Genetic and geographic differentiation in the Rio Negro tuco-tuco (Ctenomys rionegrensis): inferring the roles of migration and drift from multiple genetic markers.

Among tuco-tucos, Ctenomys rionegrensis is especially amenable to the study of the forces driving population differentiation because of the restricted geographic range it occupies in Uruguay. Within this limited area, the Rio Negro tuco-tuco is limited to sandy soils. It nonetheless exhibits remarkable variation in pelage color, including melanic, agouti, and dark-backed individuals. Two hypotheses have been put forth to explain this pattern: (1) local differentiation and fixation of alternative pelage types by genetic drift under limited gene flow; or (2) fixation by natural selection that may take place even in the presence of gene flow. A previous allozyme study rejected the genetic drift hypothesis on the basis of high inferred levels of migration. New estimates of gene flow from microsatellites and mitochondrial cytochrome b sequences were obtained for C. rionegrensis populations to further test these hypotheses. Much lower levels of gene flow were estimated with these more sensitive markers. Microsatellite-based estimates of gene flow are close to zero and may come closest to estimating current levels of migration. A lack of equilibrium between migration and genetic drift is also strongly suggested by the absence of an isolation-by-distance pattern found in all three genetic datasets. The microsatellite genotype data show that the species is strongly structured geographically, with subpopulations constituting distinct genetic entities. If current levels of gene flow are very low, as indicated by the new data, the local fixation of alternative alleles, including those responsible for pelage color polymorphism, is possible by drift alone. A scenario is thus proposed in which the species expanded in the recent past from a more restricted geographic range and has subsequently differentiated in near isolation, with genetic drift possibly playing a primary role in overall genetic differentiation. The local fixation of pelage color types could also be due to drift, but selection on this trait cannot be ruled out without direct analysis.

Animals↗

PubMed1997

Association between genetic polymorphism of the pepsinogen C gene and gastric body ulcer: the genetic predisposition is not associated with Helicobacter pylori infection.

BACKGROUND AND AIMS: The genetic trait plays a part in the pathogenesis of peptic ulcer disease. To identify a DNA marker for peptic ulcer disease, the association between the restriction fragment length polymorphism (RFLP) of the pepsinogen C (PGC) gene and peptic ulcer disease was investigated. PATIENTS AND METHODS: One hundred and seventy seven unrelated controls, 75 patients with gastric ulcer, and 70 with duodenal ulcer were studied. PGC-RFLP was analysed by polymerase chain reaction (PCR), and the association between PGC-RFLP and peptic ulcer disease was examined. The relation between the genetic association of PGC polymorphism with peptic ulcer and Helicobacter pylori infection was also examined. RESULTS: Four alleles, 480 (allele 1), 450 (allele 2), 400 (allele 3), and 310 bp (allele 4), were detected by PCR. The frequency of allele 4 was significantly higher in patients with gastric body ulcer than in controls (chi (2) = 9.92, p < 0.005). Genotypes containing allele 4 were significantly more frequent in patients with gastric body ulcer than in controls and patients with gastric angular or antral ulcer. The relative risk of gastric body ulcer associated with the presence of allele 4, compared with its absence, was 4.63 and was statistically significant (chi (2) = 14.84, p < 0.005). There were no significant differences in the allelic frequencies between H pylori positive and H pylori negative groups in controls, patients with gastric body ulcer, or patients with gastric angular or antral ulcer. Both in H pylori negative and H pylori positive cases, there was an increased frequency of allele 4 in patients with gastric body ulcer compared with controls. CONCLUSIONS: These results suggest that there is a significant association between this genetic polymorphism at the PGC gene locus and gastric body ulcer. There are differences in the genetic aetiology between gastric body ulcer and gastric angular or antral ulcer. PGC-RFLP may be used as a genetic marker for a genetic predisposition to gastric body ulcer; this genetic predisposition is not associated with H pylori infection.

Adult↗

PubMedDate not supplied

Attitudes and psychological impact of genetic testing, genetic counseling, and breast cancer risk assessment among women at increased risk.

PURPOSE/OBJECTIVES: To review research related to the psychological functioning of women with family histories of breast cancer, the impact of genetic counseling on women at increased risk, and their participation in and description of breast cancer risk evaluation programs. DATA SOURCES: Published articles and material from the World Wide Web. DATA SYNTHESIS: Findings from these sources suggest an underlying level of psychological distress in women with family histories of breast cancer. This may either increase or decrease their surveillance practices. With the onset of commercial genetic testing for BRCA1 and BRCA2, researchers have studied some of the initial psychosocial effects of genetic information on women at high risk. CONCLUSIONS: Women with family histories of breast cancer have a very high interest in genetic testing for BRCA1 and BRCA2 mutations. They have an underlying level of psychological distress that is not relieved by genetic counseling. They tend to state reasons for wanting and not wanting testing that are not polar opposites. Women who attend breast cancer risk assessment programs tend to be self-referred, Caucasian, well-educated, and of middle or upper income status. Large gaps exist in the research on women of color and those who are less educated and of lower socioeconomic status. IMPLICATIONS FOR NURSING: Nurses and other healthcare professionals should tailor care given to women at increased risk for hereditary breast cancer by using the current information related to their emotional and medical needs. Decisions regarding genetic testing, genetic counseling, and breast cancer risk assessment are highly individualized. Thus, healthcare professionals should be cautious regarding any generalizations about women at risk for breast cancer.

Adaptation, Psychological↗

PubMed2004

Phenotypic variation resulting from a deficiency of epidermal growth factor receptor in mice is caused by extensive genetic heterogeneity that can be genetically and molecularly partitioned.

The timing of lethality caused by homozygosity for a null allele of the epidermal growth factor receptor (Egfrtm1Mag) in mice is strongly dependent on genetic background. Initial attempts to genetically map background modifiers using Swiss-derived, outbred CD-1 mice were unsuccessful. To investigate the genetic architecture contributing to survival of Egfrtm1Mag homozygous embryos, the genetic variability segregating within the outbred population was partitioned by surveying viability of Egfrtm1Mag mutants using intercrosses between 129S6/SvEvTAC-Egfrtm1Mag and nine Swiss-derived, inbred strains: ALR/LtJ, ALS/LtJ, APN, APS, ICR/HaRos, NOD/LtJ, NON/LtJ, SJL/J, and SWR/J. The observations showed that these strains support varying levels of survival of Egfrtm1Mag homozygous embryos, suggesting that genetic heterogeneity within the CD-1 stock contributed to the original lack of Egfrtm1Mag modifier detection. Similar to the Swiss-derived intercrosses, nine congenic strains, derived from 129S6/SvEvTAC, AKR/J, APN, BALB/cJ, BTBR-T+ tf/tf, C3H/HeJ, C57BL/6J, DBA/2J, and FVB/NJ inbred backgrounds, also supported varying levels of survival of Egfrtm1Mag mutants. By intercrossing the congenic lines to create hybrid F1 embryos, different genetic backgrounds were found to have complementary modifiers. Analysis of the congenic lines argues against heterosis of outbred backgrounds contributing to Egfrtm1Mag phenotypic variability. A detailed analysis of the crosses suggests that modifiers function at three distinct stages of development. One class of modifiers supports survival of Egfrtm1Mag homozygous embryos to mid-gestation, another class supports development through the mid-gestation transition from yolk-sac to placental-derived nutrient sources, and a third class supports survival through later stages of gestation. Data from microarray analysis using RNA from wild-type and Egfrtm1Mag mutant placentas support the existence of extensive genetic heterogeneity and suggest that it can be molecularly partitioned. This method should be generally useful to partition heterogeneity contributing to other complex traits.

Animals↗

PubMed2006

[Current concepts in the genetics of hereditary and sporadic colorectal cancer and the role of genetics in patient management. Hereditary colorectal cancers].

Colorectal cancer (CRC) is the second leading cause of mortality of malignant diseases in Hungary and according to the incidence and prevalence of CRC Hungary is second among European countries. Hence, it is of outstanding interest to know the current concepts on pathogenesis and genetical background of CRC, as well as incorporate this knowledge in the everyday practice. In the first part of the review authors address the genetic background of hereditary colorectal cancer syndromes. In fact, a positive family history may be found in 20-30% and genetically defined trait (e.g. familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC) and Peutz-Jeghers-syndrome (PJS)) is responsible for 3-5% of all colon cancers. Germline mutations of tumor suppressor gene, APC (5q21) are found in 70-90% of the cases. Until now more than 300 mutations were identified. Though a typical mutation was not found, the location of the mutation is associated to the clinical phenotype and prognosis. Of note, beside APC mutations, biallelic mutations of the MYH gene may be found in a subset of individuals with FAP. The diagnosis of HNPCC is based on family history and the presence of Amsterdam I-Il or Bethesda criteria. The genetic background and clinical phenotype of the syndrome is heterogeneous. Mutations of different mismatch repair genes (mainly hMLH1 or hMSH2) may be identified in most cases. Genetic testing is advised in first degree relatives of FAP patients, if genetic testing is not available colonoscopic surveillance should be done starting at the age of 10-12 years. Due to the high number of mutation genetic testing is difficult in HNPCC families and colonoscopic screening should be advised to affected families.

Adaptor Proteins, Signal Transducing↗

PubMed1991

ASHG/NSGC activities related to education. The doctoral degree in genetic counseling: attitudes of genetic counselors.

All 565 full members of the National Society of Genetic Counselors were surveyed in September 1989 to assess their attitudes toward a potential doctoral degree in genetic counseling. The usable return rate was 59.6% (337/565) of the full membership. One hundred eighty (54.4%) respondents indicated a need for a doctoral degree in genetic counseling, 101 (30.5%) were undecided as to the need, and 50 (15.1%) did not see a need for such a degree. One hundred forty-seven (44.3%) respondents indicated their individual interest in pursuing a doctorate in genetic counseling, 109 (32.8%) would not pursue such a degree, and 76 (22.9%) were undecided. Beyond the generally accepted feeling that genetic counseling should expand as a professional field, the reasons cited most often for seeking the Ph.D. in genetic counseling were professional recognition, a desire to specialize in a particular area, and greater depth of knowledge. The study revealed a strongly positive attitude, among full members of the NSGC, toward establishment of a doctoral degree in genetic counseling.

Adult↗

PubMed2003

An investigation of genetic counselors' discussion of genetic discrimination with cancer risk patients.

Twenty-five genetic counselors who see familial cancer risk patients were interviewed about their definitions of genetic discrimination, perceptions of patient risk for discrimination, frequency and type of discrimination experienced by their patients, sources of information about discrimination, and what they tell patients about genetic discrimination. There was variability in participant definitions and content of discussions of genetic discrimination. Although 82% regarded risk to be low to theoretical, 40% reported possible instances of genetic discrimination, including insurance companies requiring results to cover procedures, denial of life/health insurance, social discrimination, and employment discrimination. Ninety-six percent of the sample reported always or almost always discussing genetic discrimination, and one or more of the following: insurance discrimination risks, protective legislation, no known cases positively documenting discrimination, strategies to avoid discrimination, and uncertainty of protective measures. The majority use current literature and research as information sources. Practice, policy, and research implications are discussed.

Adult↗

PubMed2000

Laws restricting health insurers' use of genetic information: impact on genetic discrimination.

Since 1991, 28 states have enacted laws that prohibit insurers' use of genetic information in pricing, issuing, or structuring health insurance. This article evaluates whether these laws reduce the extent of genetic discrimination by health insurers. From the data collected at multiple sites, we find that there are almost no well-documented cases of health insurers either asking for or using presymptomatic genetic test results in their underwriting decisions, either (a) before or after these laws have been enacted or (b) in states with or without these laws. By using both in-person interviews with insurers and a direct market test, we found that a person with a serious genetic condition who is presymptomatic faces little or no difficulty in obtaining health insurance. Furthermore, there are few indications that the degree of difficulty varies according to whether a state regulates the use of genetic information. Nevertheless, these laws have made it less likely that insurers will use genetic information in the future. Although insurers and agents are only vaguely aware of these laws, the laws have shaped industry norms and attitudes about the legitimacy of using this information.

Genetic Counseling↗

PubMed1982

Public policy implications of human genetic technology: genetic screening.

As rapid advances in human genetic research are transferred into new areas of genetic technology, questions relating to the use of these techniques will escalate. This paper examines some of the policy concerns surrounding recent developments in genetic screening. It discusses the impetus and implications of genetic screening in general, examines various applications, and analyzes the costs and benefits of screening programs currently in existence. Special emphasis is placed on whether or not screening should be considered a matter of public health and mandated on those grounds. This paper argues against any compulsory screening programs except where the disease is easily identified, applicable across social groups, and treatable. While screening services for carriers of genetic disease and prenatal diagnosis should be made available and education programs should be expanded substantially, the burden of proof for involuntary programs is placed on the proponents. There is little public health justification at this time for mandatory screening though this does not preclude future public health demands. It is argued that the goals and justification of various human genetic technologies must be examined at this time due to the rapid advancement of the research as well as the ultimate benefits promised for humankind.

Cost-Benefit Analysis↗