General regression model: A "model-free" association test for quantitative traits allowing to test for the underlying genetic model.

Most genome-wide association studies used genetic-model-based tests assuming an additive mode of inheritance, leading to underpowered association tests in case of departure from additivity. The general regression model (GRM) association test proposed by Fisher and Wilson in 1980 makes no assumption on the genetic model. Interestingly, it also allows formal testing of the underlying genetic model. We conducted a simulation study of quantitative traits to compare the power of the GRM test to the classical linear regression tests, the maximum of the three statistics (MAX), and the allele-based (allelic) tests. Simulations were performed on two samples sizes, using a large panel of genetic models, varying genetic models, minor allele frequencies, and the percentage of explained variance. In case of departure from additivity, the GRM was more powerful than the additive regression tests (power gain reaching 80%) and had similar power when the true model is additive. GRM was also as or more powerful than the MAX or allelic tests. The true simulated model was mostly retained by the GRM test. Application of GRM to HbA1c illustrates its gain in power. To conclude, GRM increases power to detect association for quantitative traits, allows determining the genetic model and is easily applicable.

A systematic review of non-genetic predictors and genetic factors of glycated haemoglobin in type 1 diabetes one year after diagnosis.

Type 1 diabetes (T1D) results from autoimmune destruction of the pancreatic ßcells. Although all T1D patients require daily administration of exogenous insulin, their insulin requirement to achieve good glycaemic control may vary significantly. Glycated haemoglobin (HbA1c) level represents a stable indicator of glycaemic control and is a reliable predictor of long-term complications of T1D. The purpose of this article is to systematically review the role of non-genetic predictors and genetic factors of HbA1c level in T1D patients after the first year of T1D, to exclude the honeymoon period. A total of 1974 articles published since January 2011 were identified and 78 were finally included in the analysis of non-genetic predictors. For genetic factors, a total of 277 articles were identified and 14 were included. The most significantly associated factors with HbA1c level are demographic (age, ethnicity, and socioeconomic status), personal (family characteristics, parental care, psychological traits...) and features related to T1D (duration of T1D, adherence to treatment …). Only a few studies have searched for genetic factors influencing HbA1c level, most of which focused on candidate genes using classical genetic statistical methods, with generally limited power and incomplete adjustment for confounding factors and multiple testing. Our review shows the complexity of explaining HbA1c level variations, which involves numerous correlated predictors. Overall, our review underlines the lack of studies investigating jointly genetic and non-genetic factors and their interactions to better understand factors influencing glycaemic control for T1D patients.

Gain of power of the general regression model compared to Cochran-Armitage Trend tests: simulation study and application to bipolar disorder.

BACKGROUND: Most genome-wide association studies assumed an additive model of inheritance which may result in significant loss of power when there is a strong departure from additivity. The General Regression Model (GRM), which allows performing an assumption-free test for association by testing for both additive effect and deviation from additive effect, may be more appropriate for association tests. Additionally, GRM allows testing the underlying genetic model. We compared the power of GRM association test to additive and other Cochran-Armitage Trend (CAT) tests through simulations and by applying GRM to a large case/control sample, the bipolar Welcome Trust Case Control Cohort data. Simulations were performed on two sets of case/control samples (1000/1000 and 2000/2000), using a large panel of genetic models. Four association tests (GRM and additive, recessive and dominant CAT tests) were applied to all replicates. RESULTS: We showed that GRM power to detect association was similar or greater than the additive CAT test, in particular in case of recessive inheritance, with up to 67% gain in power. GRM analysis of genome-wide bipolar disorder Welcome Trust Consortium data (1998 cases/3004 controls) showed significant association in the 16p12 region (rs420259; P = 3.4E-7) which has not been identified using the additive CAT test. As expected, rs42025 fitted a non-additive (recessive) model. CONCLUSIONS: GRM provides increased power compared to the additive CAT test for association studies and is easily applicable.

Mutations in myosin heavy chain 11 cause a syndrome associating thoracic aortic aneurysm/aortic dissection and patent ductus arteriosus.

We have recently described two kindreds presenting thoracic aortic aneurysm and/or aortic dissection (TAAD) and patent ductus arteriosus (PDA) and mapped the disease locus to 16p12.2-p13.13 (ref. 3). We now demonstrate that the disease is caused by mutations in the MYH11 gene affecting the C-terminal coiled-coil region of the smooth muscle myosin heavy chain, a specific contractile protein of smooth muscle cells (SMC). All individuals bearing the heterozygous mutations, even if asymptomatic, showed marked aortic stiffness. Examination of pathological aortas showed large areas of medial degeneration with very low SMC content. Abnormal immunological recognition of SM-MHC and the colocalization of wild-type and mutant rod proteins in SMC, in conjunction with differences in their coimmunoprecipitation capacities, strongly suggest a dominant-negative effect. Human MYH11 gene mutations provide the first example of a direct change in a specific SMC protein leading to an inherited arterial disease.

Genetic and functional abnormalities of the melatonin biosynthesis pathway in patients with bipolar disorder.

Patients affected by bipolar disorder (BD) frequently report abnormalities in sleep/wake cycles. In addition, they showed abnormal oscillating melatonin secretion, a key regulator of circadian rhythms and sleep patterns. The acetylserotonin O-methyltransferase (ASMT) is a key enzyme of the melatonin biosynthesis and has recently been associated with psychiatric disorders such as autism spectrum disorders and depression. In this paper, we analysed rare and common variants of ASMT in patients with BD and unaffected control subjects and performed functional analysis of these variants by assaying the ASMT activity in their B-lymphoblastoid cell lines. We sequenced the coding and the regulatory regions of the gene in a discovery sample of 345 patients with BD and 220 controls. We performed an association study on this discovery sample using common variants located in the promoter region and showed that rs4446909 was significantly associated with BD (P= 0.01) and associated with a lower mRNA level (P< 10(-4)) and a lower enzymatic activity (P< 0.05) of ASMT. A replication study and a meta-analysis using 480 independent patients with BD and 672 controls confirmed the significant association between rs4446909 and BD (P= 0.002). These results correlate with the general lower ASMT enzymatic activity observed in patients with BD (P= 0.001) compared with controls. Finally, several deleterious ASMT mutations identified in patients were associated with low ASMT activity (P= 0.01). In this study, we determined how rare and common variations in ASMT might play a role in BD vulnerability and suggest a general role of melatonin as susceptibility factor for BD.

[Patients' contribution to the review of research protocols]. / L'apport des patients dans la relecture des protocoles de recherche.

Involvement of patients in the ethical management of research protocols began by patients' associations involved in the fight against AIDS in France in the 1990s. It was the first step towards recognizing the major role of patients in research that concerns them. This article aims describing this emancipation and its consequences on the evolution of research by drawing on two experiences: 1) The one of the « Comité de patients pour la recherche clinique ¼ founded in 1998 by the « Ligue nationale contre le cancer ¼ and by the « Fédération nationale des centres de lutte contre le cancer ¼; 2) The one of the « Collège des relecteurs de l'Inserm ¼ set up in 2007.

Title: L'apport des patients dans la relecture des protocoles de recherche. Abstract: L'implication des patients dans la gestion éthique des protocoles de recherche, débutée en France dans les années 1990 par les associations de malades impliquées dans la lutte contre le syndrome de l'immunodéficience acquise (sida), a été le premier pas qui a permis de reconnaître le rôle essentiel des patients dans les recherches les concernant. Nous présentons dans cet article cette émancipation et ses conséquences sur l'évolution de la recherche, en s'appuyant sur une double expérience : celle du comité de patients pour la recherche clinique, créé en 1998 par la Ligue nationale contre le cancer et par la fédération nationale des centre de lutte contre le cancer, puis celle du Collège des relecteurs mis en place par l'Inserm en 2007.

[Healthy volunteers' protection around the world]. / VolREthics - Une initiative internationale de l'Inserm pour définir la protection des volontaires sains.

Healthy volunteers participating in biomedical research benefit from varying levels of protection in different parts of the world since they are too rarely identified as a specific subset of study participants with specific vulnerabilities and risks. These differences in protection can lead to unfair and ethically unacceptable situations. Healthy volunteers are subject to a number of risks, not only regarding the respect of their rights and of their health but they are also at risk of being exploited because of their financial situation, educational level and motivations. In the end, the scientific validity of the studies may also be called into question. Through its work, the VolREthics (Volunteers in Research and Ethics) initiative, set up by the Inserm ethics committee, outlines the ethical issues raised by the involvement of healthy volunteers in biomedical research, and highlights the need to improve their protection worldwide. Healthy volunteers are essential to scientific progress and society, and their potential vulnerabilities must be recognized and taken into account.

Title: VolREthics - Une initiative internationale de l'Inserm pour définir la protection des volontaires sains. Abstract: Les volontaires sains qui participent aux recherches biomédicales sont très rarement identifiés comme un groupe spécifique. Pourtant, de par leur vulnérabilité et les risques potentiels auxquels ils sont exposés, ils ne bénéficient que d'un niveau de protection qui reste variable selon les régions du monde. Il en résulte différents risques, non seulement pour le respect de leurs droits, de leur santé, mais également pour la validité scientifique des recherches. L'initiative internationale VolREthics (pour volontaires sains en recherche et éthique, ou Volunteers in Research and Ethics), lancée par le comité d'éthique de l'Inserm, a mis en évidence les questions éthiques soulevées par la participation des volontaires sains dans la recherche biomédicale. Elle insiste également sur la nécessité d'améliorer la protection de ces volontaires lors des recherches menées à travers le monde.

[Towards more informed consent: Making information understandable]. / Vers un consentement plus éclairé - Rendre l'information accessible.

In clinical research and care, information notices are too often reduced to complicated and hard-to-understand mandatory documents. However, every person has the right to transparent and truthful information. These considerations prompted the creation of a multidisciplinary working group in the fall of 2020, headed by the College des relecteurs de l'Inserm. This group associates the different actors involved in the development, evaluation and use of information notices: Health and research professionals, representatives of patient associations or research foundations, ethicists, jurists, scientific educators and communicators. This group has created a set of texts, pictograms and illustrations, adapted to the people concerned and accepted by all actors. These contents will be easily used by professionals through the app Noticeinfobox©. A pilot phase was conducted to generate the notices of the France Genomic Medicine Plan 2025, used for genetic examinations. This app Noticeinfobox© is a response to society's request to be an actor in its own healthcare and to adopt more ethical and responsible research.

Title: Vers un consentement plus éclairé - Rendre l'information accessible. Abstract: Trop souvent, les notices d'information proposées dans le cadre de recherches cliniques se réduisent à des documents réglementaires difficilement compréhensibles. Pourtant, les personnes concernées doivent avoir accès à une information transparente et loyale. Ces considérations ont motivé la création d'un groupe de travail pluridisciplinaire, piloté par le Collège des relecteurs de l'Inserm, associant les acteurs impliqués dans l'élaboration, l'évaluation et l'utilisation de ces notices d'information. Un ensemble de textes, pictogrammes et illustrations, adaptés aux personnes concernées, validés et facilement utilisables via une application a été créé. Une phase pilote, dans le cadre du plan France médecine génomique 2025, a permis de générer des notices simplifiées pour les examens génétiques. Dans cet article, nous présentons le travail réalisé par le groupe de travail « Notices d'information ¼ afin de répondre à la demande sociétale d'être acteur de son parcours de soin et de contribuer à une recherche plus éthique et responsable.

Genetic heterogeneity according to age at onset in bipolar disorder: a combined positional cloning and candidate gene approach.

This study is the first that formally tests for genetic heterogeneity of bipolar disorder (BD) according to age at onset (AAO) sub-groups by combining positional cloning and candidate gene approaches. Our previous genome-wide linkage-scan identified five genomic regions linked to early-onset form of BD. The present study uses association analysis to test genetic heterogeneity of candidate genes located in these five regions in a sample of 443 unrelated bipolar patients and 1,731 controls. The study involved the following steps: (1) test of heterogeneity by comparing early-onset BD patients versus later-onset BD patients; and (2) for significant results in step 1, comparison of early-onset BD patients and later-onset BD patients separately to controls. Two types of analyses were used: the single SNP test and the gene-based association test. We provide evidence for genetic heterogeneity within the ADRB2 (beta-2adrenoreceptor) gene region that is specifically associated with the early onset form of BD with an OR of 1.8. Unfortunately, the genotyping coverage of ADRB2 in the Wellcome Trust Case Control Consortium sample meant undermined our efforts to undertake a replication. However, as the ADRB2 gene product directly interacts with the CACNA1C gene product, and is known to be implicated in BD susceptibility, we conclude that further exploration of the relationships between ADRB2 and BD needs to be undertaken.

[Production of knowledge using data collected by associations of patients: The fibromyalgia example]. / Production de savoirs à partir de données collectées par les associations de malades - L'exemple de la fibromyalgie.

To respond to the social challenge of medical knowledge democratisation, numerous initiatives have been developed: information, training or consultation of patients or research applications funded by associations of patients. Only a few numbers of collaborations are initiated by the persons directly involved (patients and relatives) or fulfill association research need. We have adopted and tested such an approach with the French fibromyalgia association (Fibromyalgie France). Our work demonstrates the interest to use data collected by associations of patients to answer to their questioning or to rise further relevant research questions. Such participative approach will have a pertinent and significant impact on the knowledge of diseases and on the development of collaborative actions of research, providing a better answer to patient needs, while being methodologically rigorous.

TITLE: Production de savoirs à partir de données collectées par les associations de malades - L'exemple de la fibromyalgie. ABSTRACT: Pour répondre au défi sociétal de démocratisation de l'accès à la connaissance, différentes initiatives de recherches participatives se développent : actions d'information, de formation ou de consultation des citoyens ou par l'intermédiaire de demandes de financement par des chercheurs auprès des associations. Cependant, peu des collaborations chercheurs-malades sont à l'initiative des personnes concernées, les patients et leurs familles. Nous avons adopté et testé cette démarche à la demande et en coopération avec l'association Fibromyalgie France.

Preferential association between childhood emotional abuse and bipolar disorder.

Childhood trauma has been suggested to be involved in the susceptibility to bipolar disorder. However, case-control studies are lacking, and the preferential implication and the dose-effect of different trauma subtypes remain poorly investigated. Two hundred six bipolar patients and 94 controls completed the Childhood Trauma Questionnaire (CTQ; Bernstein et al., 1994). The CTQ total score was higher for bipolar patients than for controls. The presence of multiple trauma was significantly more frequent in bipolar patients than in controls (63% vs. 33%). Multiple logistic regression suggested that only emotional abuse was associated with bipolar disorder with a suggestive dose-effect. Clinical practice should include systematic assessment of childhood trauma among bipolar patients with a particular focus on emotional abuse.

European collaborative study of early-onset bipolar disorder: Evidence for genetic heterogeneity on 2q14 according to age at onset.

Bipolar disorder has a genetic component, but the mode of inheritance remains unclear. A previous genome scan conducted in 70 European families led to detect eight regions linked to bipolar disease. Here, we present an investigation of whether the phenotypic heterogeneity of the disorder corresponds to genetic heterogeneity in these regions using additional markers and an extended sample of families. The MLS statistic was used for linkage analyses. The predivided sample test and the maximum likelihood binomial methods were used to test genetic homogeneity between early-onset bipolar type I (cut-off of 22 years) and other types of the disorder (later onset of bipolar type I and early-onset bipolar type II), using a total of 138 independent bipolar-affected sib-pairs. Analysis of the extended sample of families supports linkage in four regions (2q14, 3p14, 16p23, and 20p12) of the eight regions of linkage suggested by our previous genome scan. Heterogeneity testing revealed genetic heterogeneity between early and late-onset bipolar type I in the 2q14 region (P = 0.0001). Only the early form of the bipolar disorder but not the late form appeared to be linked to this region. This region may therefore include a genetic factor either specifically involved in the early-onset bipolar type I or only influencing the age at onset (AAO). Our findings illustrate that stratification according to AAO may be valuable for the identification of genetic vulnerability polymorphisms. © 2010 Wiley-Liss, Inc.

Emotional hyper-reactivity in normothymic bipolar patients.

BACKGROUND: Normothymic states in bipolar disorders are generally considered to be devoid of severe symptoms. However, bipolar patients present subsyndromal symptoms for half of their lives, and often have comorbid psychiatric disorders. If we go beyond the concept of temperamental features, can we identify certain emotional characteristics distinguishing normothymic bipolar patients from normal controls? We previously showed, using self-completed questionnaires, that normothymic bipolar patients display higher levels of emotional lability and intensity than controls. OBJECTIVES: The aim of this study was to assess the emotional reactivity of normothymic bipolar patients, comparing such patients with a normal control group during an experimental mood induction procedure. METHOD: We evaluated the subjective emotional reactivity of 145 subjects (90 control subjects and 55 normothymic bipolar patients), using an emotional induction method based on the viewing of a set of 18 pictures (6 positive, 6 negative, 6 neutral) extracted from the International Affective Picture System. Subjective valence and arousal were recorded with the Self-Assessment Manikin. We also recorded startle reflexes, triggered by a tone occurring during the viewing of two-thirds of the pictures. We controlled for confounding factors, such as concurrent treatments, in all analyses. RESULTS: Normothymic bipolar patients and normal controls assessed valence and arousal similarly for positive and negative images. However, neutral images were considered more pleasant [F(1,143) = 8.4; p = 0.004] and induced a higher level of arousal [F(1,143) = 12.3; p = 0.001] in normothymic bipolar patients than in control subjects. Neutral pictures also triggered a stronger startle reflex in normothymic bipolar patients compared to controls [F(3,123) = 3.1; p = 0.03]. CONCLUSION: Normothymic bipolar patients displayed emotional hyper-reactivity, mostly evidenced in neutral situations. This feature may be linked to emotional dysregulation and is a potential endophenotype and/or a risk factor for bipolar disorders. This trait may be responsible for vulnerability to minor stressful events in everyday life. These findings have potential implications for the daily management of bipolar disorder between crises.

Antipsychotics increase vesicular glutamate transporter 2 (VGLUT2) expression in thalamolimbic pathways.

Recently the two vesicular-glutamate-transporters VGLUT1 and VGLUT2 have been cloned and characterized. VGLUT1 and VGLUT2 together label all glutamatergic neurons, but because of their distinct expression patterns in the brain they facilitate our ability to define between a VGLUT1-positive cortical and a VGLUT2-positive subcortical glutamatergic systems. We have previously demonstrated an increased cortical VGLUT1 expression as marker of antidepressant activity. Here, we assessed the effects of different psychotropic drugs on brain VGLUT2 mRNA and protein expression. The typical antipsychotic haloperidol, and the atypicals clozapine and risperidone increased VGLUT2 mRNA selectively in the central medial/medial parafascicular, paraventricular and intermediodorsal thalamic nuclei; VGLUT2 protein was accordingly amplified in paraventricular and ventral striatum and in prefrontal cortex. The antidepressants fluoxetine and desipramine and the sedative anxiolytic diazepam had no effect. These results highlight the implication of thalamo-limbic glutamatergic pathways in the action of antipsychotics. Increased VGLUT2 expression in these neurons might constitute a marker for antipsychotic activity and subcortical glutamate neurotransmission might be a possible novel target for future generation antipsychotics.

Beyond genetics: childhood affective trauma in bipolar disorder.

OBJECTIVES: Despite the demonstrated high heritability of bipolar disorder, few susceptibility genes have been identified and linkage and/or association studies have produced conflicting results. This search for susceptibility genes is hampered by several methodological limitations, and environmental risk factors for the disease (requiring incorporation into analyses) remain misunderstood. Among them, childhood trauma is probably the most promising environmental factor for further investigation. The objectives are to review the arguments in favor of an association between childhood trauma and bipolar disorder and to discuss the interpretations of such an observation. METHODS: We computed a literature search using PubMed to identify relevant publications concerning childhood trauma and bipolar disorder. We also present some personal data in this field. RESULTS: Growing evidence suggests that incidences of childhood trauma are frequent and severe in bipolar disorder, probably affect the clinical expression of the disease in terms of suicidal behavior and age at onset, and also have an insidious influence on the affective functioning of patients between episodes. The relationships between childhood trauma and bipolar disorder suggest several interpretations, mainly a causal link, a neurodevelopmental consequence, or the intergenerational transmission of traumatic experiences. The neurobiological consequences of childhood trauma on a maturing brain remain unclear, although such stressors may alter the organization of brain development, leading to inadequate affective regulation. CONCLUSIONS: Childhood trauma is associated with bipolar disorder and its clinical expression and may interact with genetic susceptibility factors. Although not completely understood, the relationships between childhood trauma and bipolar disorder require further attention. Several suggestions for further exploration of this environmental factor and of its interaction with susceptibility genes are proposed.

Association between the PPP3CC gene, coding for the calcineurin gamma catalytic subunit, and bipolar disorder.

BACKGROUND: Calcineurin is a neuron-enriched phosphatase that regulates synaptic plasticity and neuronal adaptation. Activation of calcineurin, overall, antagonizes the effects of the cyclic AMP activated protein/kinase A. Thus, kinase/phosphatase dynamic balance seems to be critical for transition to long-term cellular responses in neurons, and disruption of this equilibrium should induce behavioral impairments in animal models. Genetic animal models, as well as post-mortem studies in humans have implicated calcineurin dependent calcium and cyclic AMP regulated phosphorylation/dephosphorylation in both affective responses and psychosis. Recently, genetic association between schizophrenia and genetic variation of the human calcineurin A gamma subunit gene (PPP3CC) has been reported. METHODS: Based on the assumption of the common underlying genetic factor in schizophrenia and bipolar affective disorder (BPAD), we performed association analysis of CC33 and CCS3 polymorphisms of the PPP3CC gene reported to be associated with schizophrenia in a French sample of 115 BPAD patients and 97 healthy controls. RESULTS: Carrying 'CT' or 'TT' genotypes of the PPP3CC-CC33 polymorphism increased risk to develop BPAD comparing to carry 'CC' genotype (OR = 1.8 [1.01-3.0]; p = 0.05). For the PPP3CC-CCS3 polymorphism, 'AG' or 'GG' carriers have an increased risk to develop BPAD than 'AA' carriers (OR = 2.8 [1.5-5.2]). The CC33 and CCS3 polymorphisms were observed in significant linkage disequilibrium (D' = 0.91, r2 = 0.72). Haplotype frequencies were significantly different in BPAD patients than in controls (p = 0.03), with a significant over-transmission of the 'TG' haplotype in BPAD patients (p = 0.001). CONCLUSION: We suggest that the PPP3CC gene might be a susceptibility gene for BPAD, in accordance with current neurobiological hypotheses that implicate dysregulation of signal-transduction pathways, such as those regulated by calcineurin, in the etiology of affective disorders.

Construction and validation of a dimensional scale exploring mood disorders: MAThyS (Multidimensional Assessment of Thymic States).

BACKGROUND: The boundaries between mood states in bipolar disorders are not clear when they are associated with mixed characteristics. This leads to some confusion to define appropriate therapeutic strategies. A dimensional approach might help to better define bipolar moods states and more specifically those with mixed features. Therefore, we proposed a new tool based on a dimensional approach, built with a priori five sub-scales and focus on emotional reactivity rather than exclusively on mood tonality. This study was designed to validate this MAThyS Scale (Multidimensional Assessment of Thymic States). METHODS: One hundred and ninety six subjects were included: 44 controls and 152 bipolar patients in various states: euthymic, manic or depressed. The MAThyS is a visual analogic scale consisting of 20 items. These items corresponded to five quantitative dimensions ranging from inhibition to excitation: emotional reactivity, thought processes, psychomotor function, motivation and sensory perception. They were selected as they represent clinically relevant quantitative traits. RESULTS: Confirmatory analyses demonstrated a good validity for this scale, and a good internal consistency (Cronbach's alpha coefficient = 0.95). The MathyS scale is moderately correlated of both the MADRS scale (depressive score; r = -0.45) and the MAS scale (manic score; r = 0.56). When considering the Kaiser-Guttman rule and the scree plot, our model of 5 factors seems to be valid. The four first factors have an eigenvalue greater than 1.0 and the eigenvalue of the factor five is 0.97. In the scree plot, the "elbow", or the point at which the curve bends, indicates 5 factors to extract. This 5 factors structure explains 68 per cent of variance. CONCLUSION: The characterisation of bipolar mood states based on a global score assessing inhibition/activation process (total score of the MATHyS) associated with descriptive analysis on sub-scores such as emotional reactivity (rather than the classical opposition euphoria/sadness) can be useful to better understand the broad spectrum of mixed states.

Parallel loss of hippocampal LTD and cognitive flexibility in a genetic model of hyperdopaminergia.

Dopamine-mediated neurotransmission has been implicated in the modulation of synaptic plasticity and in the mechanisms underlying learning and memory. In the present study, we tested different forms of activity-dependent neuronal and behavioral plasticity in knockout mice for the dopamine transporter (DAT-KO), which constitute a unique genetic model of constitutive hyperdopaminergia. We report that DAT-KO mice exhibit slightly increased long-term potentiation and severely decreased long-term depression at hippocampal CA3-CA1 excitatory synapses. Mutant mice also show impaired adaptation to environmental changes in the Morris watermaze. Both the electrophysiological and behavioral phenotypes are reversed by the dopamine antagonist haloperidol, suggesting that hyperdopaminergia is involved in these deficits. These findings support the modulation by dopamine of synaptic plasticity and cognitive flexibility. The behavioral deficits seen in DAT-KO mice are reminiscent of the deficits in executive functions observed in dopamine-related neuropsychiatric disorders, suggesting that the study of DAT-KO mice can contribute to the understanding of the molecular basis of these disorders.

Shared executive dysfunctions in unaffected relatives of patients with autism and obsessive-compulsive disorder.

BACKGROUND: Executive dysfunctions have been studied as a potential endophenotype associated with the genetic basis of autism. Given that recent findings from clinical and molecular genetic studies suggest that autism and obsessive-compulsive disorder (OCD) could share a common pattern of heritability, we assessed executive functions as a possible common cognitive endophenotype in unaffected family members of individuals with either autism or OCD. METHODS: Five tests assessing executive functions (Tower of London, verbal fluency, design fluency, trail making and association fluency) were proposed to 58 unaffected first-degree relatives (parents and siblings) of probands with autism and 64 unaffected first-degree relatives of OCD patients. Results were compared with those of 47 healthy controls matched for age, sex, and level of education. RESULTS: In the Tower of London test, both groups of unaffected relatives showed significantly lower scores and longer response times compared with controls. No differences were observed between autism and OCD relatives and healthy controls in the four other tasks (verbal fluency, design fluency, trail making test and association fluency). CONCLUSIONS: Our findings show the existence of executive dysfunction in the unaffected first-degree relatives of probands with OCD, similar to those observed in the relatives of patients with autism. These results support and extend previous cognitive studies on probands indicating executive dysfunctions in autism and OCD. Planning and working memory processes could thus represent a common cognitive endophenotype in autism and OCD that could help in the identification of genes conferring vulnerability to these disorders.

Mapping of familial thoracic aortic aneurysm/dissection with patent ductus arteriosus to 16p12.2-p13.13.

BACKGROUND: Three loci have been shown to be responsible for nonsyndromic familial thoracic aortic aneurysms (TAAs) and aortic dissections (ADs). We recently described a large family in which TAA/AD associates with patent ductus arteriosus (PDA) and provided genetic arguments for a unique pathophysiological entity. METHODS AND RESULTS: Genome-wide scan was performed in 40 subjects belonging to 3 generations in this large pedigree. Using the 7 TAA/AD cases as affected, we observed positive 2-point LOD scores on adjacent markers at chromosome 16p, with a maximum LOD score value of 2.73 at theta=0, a value that increased to 3.56 when 5 PDA cases were included. Multipoint linkage analysis yielded a maximum LOD score of 4.14 in the vicinity of marker D16S3103. Fine mapping allowed the observation of recombinant haplotypes that delimited a critical 20-cM interval at 16p12.2-p13.13. Automatic determination of aortic compliance with cine MRI showed that all subjects bearing the disease haplotype, even asymptomatic, displayed a very low level of aortic compliance and distensibility. Aortic stiffness was strongly associated with disease haplotype with a marked effect of age, indicating subclinical and early manifestation of the disease. CONCLUSIONS: Genetic analysis of this family identified a unique locus responsible for both TAA/AD and PDA at chromosome 16p12.2-p13.13 with aortic stiffness as an early hallmark of the disease. TAA/AD with PDA is a new monogenic entity among the genetically heterogeneous group of TAA/AD disease.