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PubMed2001

[Introduction to genetic psychiatry: progress in uncovering genetic susceptibility to psychiatric disorders].

The recent progress in human genetics suggests major benefits in clinical practice, including psychiatry. This article introduces the research methodology used in psychiatric genetics and explains how it is applied, for a better understanding of the challenges facing psychiatric genetics and the strategies being used to overcome them. We will review the evidence of genetic factors in psychiatric disorder etiology as well as the specificity or non-specificity of their expression. We will discuss problems associated with the approximate nature of diagnostic methods, the incomplete penetrance and the genetic heterogeneity of psychiatric disorders, the presence of phenocopies and our uncertainty concerning the mode of inheritance of psychiatric disorders. Finally, we will provide an overview of the most promising results and set out priorities for future studies.

Genetic Markers↗

PubMed1998

A systematic study of oligodendrocyte growth factors as candidates for genetic susceptibility to MS. French Multiple Sclerosis Genetics Group.

OBJECTIVE: To test 23 genes coding for growth factors and their receptors as candidates for MS genetic susceptibility in 84 multiplex families of French origin by linkage analysis. BACKGROUND: Epidemiologic studies have indicated that genetic susceptibility in MS exists. To identify MS susceptibility genes, association and linkage studies were performed with candidate genes suggested by the pathology of MS. The most consistent result was genetic association and linkage of MS to human leukocyte antigen (HLA) DR15. Recent advances in the knowledge of MS pathology have suggested that the oligodendrocyte, the myelin-forming cell in the CNS, and its growth factors might play a crucial role in MS. METHODS: Fifty-two polymorphic markers within or flanking 23 candidate genes were used. Data were analyzed with the maximum likelihood score (MLS) approach. We also searched for a genetic interaction with HLA. RESULTS: Negative results were obtained for all candidate genes. The lower limits of the relative risk (Xs) possibly excluded for any candidate gene ranged from 1.3 to 2.8. Positive MLS values (up to 0.93) were observed for transforming growth factor beta 3 (TGFbeta3) in HLA DR15-associated families, suggesting a possible role for this growth factor in interaction with HLA. CONCLUSIONS: Oligodendrocyte growth factors do not play a significant role in MS genetic susceptibility, at least in the tested sample. TGFbeta3, the only gene highlighted by this study, deserves further analysis.

Adult↗

PubMed2026

Shared Genetic Basis, Biological Function and Causal Relationship Between Sleep Traits and Hypothyroidism: Evidence from a Comprehensive Genetic Analysis.

BACKGROUND: This research attempts to clarify whether there are any genetic similarities between sleep traits and hypothyroidism based on publicly accessible large-scale genomewide association studies. METHODS: The methodology included colocalization analysis, cross-phenotype association analysis, and linkage disequilibrium score regression analysis to find common genetic overlap. Through tissue function specificity and functional mapping, we were able to identify the shared genetic level. Genetic instrumental factors were used for causal inference in two-sample univariate and multivariable Mendelian randomization analyses. RESULTS: A hereditary correlation between hypothyroidism and napping during the day and getting up in the morning (rg= -0.0982, P= 0.0007; rg= -0.101, P= 0.0001). MAGI3, and HLA-DRB1 BX296568.1 may be potential targets for shared treatments. Colocalization and tissue-specific analysis demonstrated that the common genes and SNPs were identified in the thyroid, lung, brain, and lymphatic tissues. Functional analysis emphasized the importance of these common genes in processes like as protein transport, inflammatory response, and MHC class II protein synthesis. Furthermore, an association has been established between hypothyroidism and sleep duration (IVW, OR 1.5208; 95% CI 1.1142-2.0758, P=0.0082) and getting up in the morning (IVW, OR 1.8375; 95%CI: 1.4502-2.3284, P=4.73E-07). Furthermore, the reverse MR analysis revealed no causal connection between aberrant sleep traits and hypothyroidism. The enduring impact of insomnia on hypothyroidism persists despite controlling for alcohol consumption and smoking habits. CONCLUSION: Certain genetic correlations between sleep traits and hypothyroidism have been emphasized. These findings may elucidate the origin of comorbidity and have implications for future clinical trials.

Humans↗

PubMed2002

Estimates of genetic parameters and genetic change for reproduction, weight, and wool characteristics of Columbia sheep.

Genetic parameters from both single-trait and bivariate analyses for prolificacy, weight and wool traits were estimated using REML with animal models for Columbia sheep from data collected from 1950 to 1998 at the U.S. Sheep Experiment Station (USSES), Dubois, ID. Breeding values from both single-trait and seven-trait analyses calculated using the parameters estimated from the single-trait and bivariate analyses were compared with respect to genetic trends. Number of observations were 31,401 for litter size at birth and litter size at weaning, 24,741 for birth weight, 23,903 for weaning weight, 29,572 for fleece weight and fleece grade, and 2,449 for staple length. Direct heritability estimates from single-trait analyses were 0.09 for litter size at birth, 0.06 for litter size at weaning, 0.27 for birth weight, 0.16 for weaning weight, 0.53 for fleece weight, 0.41 for fleece grade, and 0.55 for staple length. Estimate of direct genetic correlation between littersize at birth and weaning was 0.84 and between birth and weaning weights was 0.56. Estimate of genetic correlation between fleece weight and staple length was positive (0.55) but negative between fleece weight and fleece grade (-0.47) and between staple length and fleece grade (-0.70). Estimates of genetic correlations were positive but small between birth weight and litter size traits and moderate and positive between weaning weight and litter size traits. Fleece weight was lowly and negatively correlated with both litter size traits. Fleece grade was lowly and positively correlated with both litter size traits, while staple length was lowly and negatively correlated with the litter size traits. Estimates of correlations between weight traits and fleece weight were positive and low to moderate. Estimates of correlations between weight traits and fleece grade were negative and small. Estimates of correlations between staple length and birth weight (0.05) and weaning weight were small (-0.04). Estimated breeding values averaged by year of birth from both the single-trait and multiple-trait analyses for the prolificacy and weight traits increased over time, but were unchanged for the wool traits. Estimated changes in breeding values over time did not differ substantially for single-trait and multiple-trait analyses, except for traits highly correlated with another trait that was responding to selection.

Animals↗

PubMed2003

Estimates of genetic parameters and genetic change for reproduction, weight, and wool characteristics of Targhee sheep.

Genetic parameters from both single-trait and bivariate analyses for prolificacy, weight, and wool traits were estimated using REML with animal models for Targhee sheep from data collected from 1950 to 1998 at the U.S. Sheep Experiment Station, Dubois, ID. Breeding values from both single-trait and seven-trait analyses calculated with the parameters estimated from the single-trait and bivariate analyses were compared across years of birth with respect to genetic trends. The numbers of observations were 38,625 for litter size at birth and litter size at weaning, 33,994 for birth weight, 32,715 for weaning weight, 36,807 for fleece weight and fleece grade, and 3,341 for staple length. Direct heritability estimates from single-trait analyses were 0.10 for litter size at birth, 0.07 for litter size at weaning, 0.25 for birth weight, 0.22 for weaning weight, 0.54 for fleece weight, 0.41 for fleece grade, and 0.65 for staple length. Estimate of direct genetic correlation between litter size at birth and weaning was 0.77 and between birth and weaning weights was 0.52. The estimate of genetic correlation between fleece weight and staple length was positive (0.54), but was negative between fleece weight and fleece grade (-0.47) and between staple length and fleece grade (-0.69). Estimates of genetic correlations were near zero between birth weight and litter size traits and small and positive between weaning weight and litter size traits. Fleece weight was slightly and negatively correlated with both litter size traits. Fleece grade was slightly and positively correlated with both litter size traits. Estimates of correlations between staple length and litter size at birth (-0.14) and litter size at weaning (0.05) were small. Estimates of correlations between weight traits and fleece weight were positive and low to moderate. Estimates of correlations between weight traits and fleece grade were negative and small, whereas estimates between weight traits and staple length were positive and small. Estimated breeding values averaged by year of birth from both the single- and seven-trait analyses for the prolificacy and weight traits increased over time, whereas those for fleece weight decreased slightly and those for the other wool traits were unchanged. Estimated changes in breeding values over time did not differ substantially for the single-trait and seven-trait analyses, except for traits highly correlated with another trait that was responding to selection.

Animals↗

PubMedDate not supplied

Applications of molecular genetics technology for prenatal diagnosis of genetic disease.

Information about the studies currently available and guidelines for identifying genetics resources, both clinical and laboratory, for provision of these services is provided. Rapid progress in the field of molecular genetics has provided increased opportunities for carrier and presymptomatic testing and prenatal diagnosis of numerous genetic diseases. The development of these diverse diagnostic services creates new challenges for clinical laboratory professionals who are likely to receive requests for these studies. Crucial decisions must be made in family identification for testing and in posttesting genetic counseling. Specific case examples are presented to illustrate the potential benefits and limitations of these studies. The molecular techniques currently available provide families with highly accurate information about their genetic risks.

Female↗

PubMed2001

[Genetic counseling versus genetic self testing: what challenges?].

The development of molecular genetics allows us to have access to an increasing number of informations on our own genetic code. This leads to a new form of medical activity, called predictive and preclinical medicine. It involves significant ethical stakes in terms of individual information and consent for the test as well as in terms of support for the patient which is summarized by the concept of "genetic council". The self-test, which bypasses this medical supervision, represents, for the patient becoming a consumer, a threat from the emotional point of view as well as from a social perspective (insurance, access to the working market). This analysis shows that the only real driving force for the development of the genetic self-test is commercial. To resist what is sometimes called "genetic shopping" one must consider an ethical, deontological and social priority.

Ethics, Medical↗

PubMedDate not supplied

[An approach to genetic monitoring via a genetic registry].

The analysis of the selective excerpt of the children with the inherited disorders has been made on the basis of the Kiev Medical Genetic Center, where the regional anonymous syndromological computer register has been organized. Register's file during 1993-96 has the information about 883 families that has a genetically ill proband. Genetic syndrome has been diagnosed in 78.02% (105 nosological points). The information taken from the register has allowed for the first time to distinguish the inherited pathology from the acquired one, so the new mutation from 30.23% out of all registered inherited disease. The necessity of the creation of the National Genetic Register in the Ukraine and the new conception of the two-stage genetical monitoring of the population has been proved.

Child↗

PubMedDate not supplied

Genetic structure and affinities of the Corsican population (France): classical genetic markers analysis.

The frequencies of 19 classical genetic markers for a total of 54 alleles were studied in a sample of 1,164 individuals born and residing in five different regions of Corsica. The results, which are also discussed in the context of the Mediterranean populations, show the existence within Corsica of a certain genetic differentiation between north and south which follows the linguistic subdivision differentiation. Compared to the other Mediterranean populations, Corsica also appears to be greatly differentiated from the populations of regions such as France and Tuscany, regions which have had great political and cultural influence. The Mediterranean population most comparable to Corsica is Sardinia. Despite their common origin, however, they do not prove to be absolutely identical. The genetic characteristics of Corsica and their relationship with the Mediterranean populations are interpreted in terms of demographic and matrimonial structure, isolation, and genetic drift.

Alleles↗

PubMed2025

The impact of genetic counselor involvement in genetic and genomic test order review: A scoping review.

PURPOSE: The increasing complexity of genetic technologies paired with more genetic tests being ordered by nongenetic health care providers, has resulted in an increase in the number of inappropriately ordered tests. Genetic counselors (GCs) are ideally suited to assess the appropriateness of a genetic test. METHODS: We performed a scoping review of GC involvement in utilization management initiatives in order to describe the impact of having GCs involved in this process. Five databases (MEDLINE, EMBASE, CINHAL, EBM reviews, and Web of Science Core Collection) and gray literature were searched. We considered literature published in English since 2010. RESULTS: A total of 51 studies were included. The most commonly evaluated outcomes included cancellation rate, economic efficiencies, impact on medical management, diagnostic rate, and time or triage efficiencies. Several studies also described GC impact on nongenetic health care providers. CONCLUSION: Employment of GCs in the laboratory has been implemented widely as a solution to test misordering. These studies describe ways in which GCs can be integrated into testing workflows to reduce the number of inappropriate tests and have wider impacts on nongenetic health care providers' ordering practices and the patient experience.

Humans↗

PubMed2004

Functional genetic polymorphisms in cytokines and metabolic genes as additional genetic markers for susceptibility to develop type 1 diabetes.

Genetic association with type 1 diabetes (T1D) has been established for two chromosomal regions: HLA DQ/DR (IDDM1) and INS VNTR (IDDM2). To identify additional genetic markers, we tested polymorphisms in regulatory regions of several cytokine and important metabolic genes. These polymorphisms exhibit functional consequences for expression and function. Functional genetic polymorphisms of proinflammatory (T-helper-1: IL-2, IL-12 and IFN-gamma), anti-inflammatory (T-helper-2: IL-4, IL-6 and IL-10) and metabolic (IGF-I, VDR and INS) genes were determined in 206 Dutch simplex families with juvenile onset T1D and the results were analysed using the transmission disequilibrium test. Significantly increased transmission to T1D probands was observed for the loci IDDM1, IDDM2 and the vitamin D receptor. Although none of the other individual polymorphisms was associated with disease individually, the combination of T-helper-2 and metabolic/growth alleles IL-10(*)R2, IL-4(*)C, VDR(*)C and IGF-I(*)wt was found to be transmitted more frequently than expected (67%, P(c)=0.015). We conclude that additional genetic predisposition to T1D is defined by combinations of markers (eg Th2 and metabolic) rather than by a single marker. The consequences of the increased transmission of a low Th2 expressing genotypes together with a normal Th1 profile may result in a net proinflammatory cytokine expression pattern.

Adolescent↗

PubMed2000

Genetics of adaptive radiation in Hawaiian species of Tetramolopium (Asteraceae). III. Evolutionary genetics of sex expression.

Despite numerous studies of speciation on oceanic islands, few insights exist on the genetic changes involved in the origin and diversification of island taxa. Here we report a genetic analysis of the evolutionary change in sex expression in Hawaiian Tetramolopium. The most diverse clade in the genus is characterized by a monoecious breeding system. The breeding system resulted from a change in sex expression in disc florets from the ancestral hermaphroditic condition to the derived male state. Analysis of an F2 population from a cross between the two forms of sex expression indicates two regions of the Tetramolopium linkage map are associated with the loss of female function in disc florets. Quantitative trait locus mapping of the two linkage groups confirms that two loci control 56% of the phenotypic variation of the trait in the F2 population. Additive and dominance effects are apparent but no statistical evidence of epistasis was found. Several related reproductive traits also have few genetic associations on the linkage map, but are generally distinct from the control of sex expression. Although modifier loci are likely to be involved, the apparent simple genetic change underlying sex expression parallels a major evolutionary diversification in Hawaiian Tetramolopium and may have initiated the divergence of this novel clade.

Adaptation, Biological↗

PubMed2003

A reassessment of genetic diversity in Icelanders: strong evidence from multiple loci for relative homogeneity caused by genetic drift.

There has been some controversy in the literature concerning whether Icelanders are genetically homogenous or heterogeneous relative to other European populations. We reassess this question in the light of large data sets spanning 83 autosomal SNP loci, 14 serogenetic loci, 6622 Y-chromosomes and 3214 sequences from mtDNA hypervariable segments 1 and 2 (HVS1 and HVS2). Our results strongly support the hypothesis that genetic drift, with a consequent loss of variation, has had a greater impact on Icelanders than most other Europeans. We also analyse 7245 HVS1 sequences from 25 European populations. In line with other studies, we observe a deficit of rare HVS1 haplotypes and an excess of intermediate frequency haplotypes in Icelanders compared to most European populations, with some measures of genetic diversity indicating relative heterogeneity and others indicating relative homogeneity of Icelanders. Simulations indicate that genetic drift, and not admixture (as proposed by Arnason, 2003) is the most likely cause of the atypical Icelandic HVS1 frequency spectrum. These simulations reveal that gene diversity (heterozygosity) and mean pairwise differences are largely insensitive to events in recent population history, while statistics based on the number of haplotypes or segregating sites are much more sensitive. Overall, our analyses strongly indicate that the Icelandic gene pool is less heterogeneous than those of most other European populations.

Chromosomes, Human, Y↗

PubMed2005

The effect of genetic drift in a young genetically isolated population.

The genetic make-up of genetically isolated populations may differ from a general population as a result of genetic drift and founder effects. We assessed the extent of this deviation in a recently isolated population located in the southwest of the Netherlands and studied as part of the Genetic Research in Isolated Population (GRIP) program. A gene-dropping experiment was performed in a large pedigree from this isolate, assuming different initial frequencies in the population founders came from. Allelic frequencies in the last generations of this pedigree were estimated. Simulation analysis showed large fluctuations, as measured by variation coefficient and sufficient loss probability, when initial frequencies were lower than or equal to 1%. For initial frequencies larger than 1% the fluctuations were small. We also analyzed mean heterozygosity and allele diversity of 592 markers in a random sample from the GRIP population. The results were compared with a general population (CEPH sample), old large isolate (Icelandic sample) and the small-sized population of Talana (Sardinia). GRIP mean heterozygosity and mean number of alleles were significantly lower as compared with CEPH and Iceland, but much higher when compared with the Talana population. We also concluded that the findings from the GRIP population for common variants (>1%) are likely to be extendable to other young isolates in Europe as well as to outbred populations.

Cohort Studies↗

PubMed2004

Genetic architecture of idiopathic generalized epilepsy: clinical genetic analysis of 55 multiplex families.

PURPOSE: In families with idiopathic generalized epilepsy (IGE), multiple IGE subsyndromes may occur. We performed a genetic study of IGE families to clarify the genetic relation of the IGE subsyndromes and to improve understanding of the mode(s) of inheritance. METHODS: Clinical and genealogic data were obtained on probands with IGE and family members with a history of seizures. Families were grouped according to the probands' IGE subsyndrome: childhood absence epilepsy (CAE), juvenile absence epilepsy (JAE), juvenile myoclonic epilepsy (JME), and IGE with tonic-clonic seizures only (IGE-TCS). The subsyndromes in the relatives were analyzed. Mutations in genes encoding alpha1 and gamma 2 gamma-aminobutyric acid (GABA)-receptor subunits, alpha1 and beta1 sodium channel subunits, and the chloride channel CLC-2 were sought. RESULTS: Fifty-five families were studied. 122 (13%) of 937 first- and second-degree relatives had seizures. Phenotypic concordance within families of CAE and JME probands was 28 and 27%, respectively. JAE and IGE-TCS families had a much lower concordance (10 and 13%), and in the JAE group, 31% of relatives had CAE. JME was rare among affected relatives of CAE and JAE probands and vice versa. Mothers were more frequently affected than fathers. No GABA-receptor or sodium or chloride channel gene mutations were identified. CONCLUSIONS: The clinical genetic analysis of this set of families suggests that CAE and JAE share a close genetic relation, whereas JME is a more distinct entity. Febrile seizures and epilepsy with unclassified tonic-clonic seizures were frequent in affected relatives of all IGE individuals, perhaps representing a nonspecific susceptibility to seizures. A maternal effect also was seen. Our findings are consistent with an oligogenic model of inheritance.

Adolescent↗

PubMed2006

Genetic research and genetic information: a health information professional's perspective on the benefits and risks.

BACKGROUND: The completion of the Human Genome Project, and recent breakthroughs in identifying the genes both directly responsible for and contributing to the severity of specific diseases and disabilities in humans offer great potential for future health care. AIM: The aim of the paper is to inform the health information community of these developments in order to foster debate over their wide-reaching implications. METHODS: The article outlines recent research in this area and explains how our growing understanding opens the way for improved diagnosis of disease, detection of possible predisposition to specific diseases, the interaction between genetics and environmental aspects such as diet, as well as enabling gene therapy and preventative actions. This new knowledge also opens the way for the use of pharmacogenetic information to enhance the efficacy of pharmaceuticals and to avoid toxic reactions. RESULTS: These advances have significant social, legal and ethical implications. Most countries have limited legislative control over the use and protection of genetic information about individuals. CONCLUSION: There is a role for health information professionals to play in promoting wider public knowledge of genetic research and its implications, in fostering public debate on key issues, and in seeking clearer policies in the health sector concerning the use of genetic information about individuals.

Genetic Counseling↗

PubMed2006

Simultaneous estimation of mixing rates and genetic drift under successive sampling of genetic markers with application to the mud crab (Scylla paramamosain) in Japan.

In stock enhancement programs, it is important to assess mixing rates of released individuals in stocks. For this purpose, genetic stock identification has been applied. The allele frequencies in a composite population are expressed as a mixture of the allele frequencies in the natural and released populations. The estimation of mixing rates is possible, under successive sampling from the composite population, on the basis of temporal changes in allele frequencies. The allele frequencies in the natural population may be estimated from those of the composite population in the preceding year. However, it should be noted that these frequencies can vary between generations due to genetic drift. In this article, we develop a new method for simultaneous estimation of mixing rates and genetic drift in a stock enhancement program. Numerical simulation shows that our procedure estimates the mixing rate with little bias. Although the genetic drift is underestimated when the amount of information is small, reduction of the bias is possible by analyzing multiple unlinked loci. The method was applied to real data on mud crab stocking, and the result showed a yearly variation in the mixing rate.

Animals↗

PubMed1999

Apocalypse...now? Molecular epidemiology, predictive genetic tests, and social communication of genetic contents.

The author analyzes the underlying theoretical aspects in the construction of the molecular watershed of epidemiology and the concept of genetic risk, focusing on issues raised by contemporary reality: new technologies, globalization, proliferation of communications strategies, and the dilution of identity matrices. He discusses problems pertaining to the establishment of such new interdisciplinary fields as molecular epidemiology and molecular genetics. Finally, he analyzes the repercussions of the social communication of genetic content, especially as related to predictive genetic tests and cloning of animals, based on triumphal, deterministic metaphors sustaining beliefs relating to the existence and supremacy of concepts such as 'purity', 'essence', and 'unification' of rational, integrated 'I's/egos'.

Genetic Markers↗