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A Malafosse

Publications and source records attributed to A Malafosse.

At least 19 recordsLinked to original sources
PubMed2006

Genome-wide scan for genes involved in bipolar affective disorder in 70 European families ascertained through a bipolar type I early-onset proband: supportive evidence for linkage at 3p14.

Preliminary studies suggested that age at onset (AAO) may help to define homogeneous bipolar affective disorder (BPAD) subtypes. This candidate symptom approach might be useful to identify vulnerability genes. Thus, the probability of detecting major disease-causing genes might be increased by focusing on families with early-onset BPAD type I probands. This study was conducted as part of the European Collaborative Study of Early Onset BPAD (France, Germany, Ireland, Scotland, Switzerland, England, Slovenia). We performed a genome-wide search with 384 microsatellite markers using non-parametric linkage analysis in 87 sib-pairs ascertained through an early-onset BPAD type I proband (AAO of 21 years or below). Non-parametric multipoint analysis suggested eight regions of linkage with P-values<0.01 (2p21, 2q14.3, 3p14, 5q33, 7q36, 10q23, 16q23 and 20p12). The 3p14 region showed the most significant linkage (genome-wide P-value estimated over 10 000 simulated replicates of 0.015 [0.01-0.02]). After genome-wide search analysis, we performed additional linkage analyses with increased marker density using markers in four regions suggestive for linkage and having an information contents lower than 75% (3p14, 10q23, 16q23 and 20p12). For these regions, the information content improved by about 10%. In chromosome 3, the non-parametric linkage score increased from 3.51 to 3.83. This study is the first to use early-onset bipolar type I probands in an attempt to increase sample homogeneity. These preliminary findings require confirmation in independent panels of families.

Adolescent↗
PubMed2004

Prevalence of DSM-IV psychiatric disorder in the French elderly population.

BACKGROUND: France has high rates of psychotropic drug consumption and suicide in the elderly population, but it has not yet been possible to determine whether this is due to exceptionally high morbidity rates. AIMS: To describe the first longitudinal population study of psychiatric disorder undertaken in France, and to estimate current and lifetime prevalences and age of onset of psychiatric disorder. METHOD: A study group of 1873 non-institutionalised persons aged 65 years and over was randomly recruited from the Montpellier district electoral rolls. The Mini International Neuropsychiatric Interview was used to assess current and lifetime symptoms. Cases identified by the application of DSM-IV criteria were re-examined by a clinical panel. RESULTS: Forty-six per cent of the study population had experienced a mental disorder in their lifetime, and 3.7% had made a suicide attempt. Lifetime prevalence of major depression was 26.5% and 30% for anxiety disorders. Current prevalence rates were 14.2% for anxiety disorders, 10.7% for phobia, 3% for major depression and 1.7% for psychosis. CONCLUSIONS: Results show very high rates of lifetime but not current major depression. Rates of current phobia and suicidal ideation in the very elderly are also high compared with other studies. The rates reported are likely to be underestimates.

Age of Onset↗
PubMed2003

Antidepressant-induced mania, rapid cycling and the serotonin transporter gene polymorphism.

The genes involved in the serotonin system are major candidates in association studies on affective disorders and responses to antidepressants. We studied a functional polymorphism of the serotonin transporter (5-HTT) gene (a 44 bp insertion/deletion in the 5-HTT-linked polymorphic region (5-HTTLPR)) and lifetime history of antidepressant-induced mania (AIM) in a population of 305 patients with bipolar affective disorder. AIM was defined using a broad definition and a restrictive definition. No association was found between the "s" allele of the 5-HTTLPR and AIM for either definition. However, we found an association between the 5-HTTLPR and lifetime history of rapid cycling in a subsample of patients (for allele and genotype distributions: exact probability, p=0.0009 and chi(2)=9.4; df=1; p=0.002, respectively). These results may help to explain the conflicting association results obtained with the 5-HTT gene polymorphism, in particular with AIM. Indeed, the precise phenotype associated with the 5-HTT gene is unclear. The association between the "s" allele and rapid cycling may provide further evidence for an association between the 5-HTTLPR "s" allele and a pattern of affective instability.

Adult↗
PubMed2002

How mutations in the nAChRs can cause ADNFLE epilepsy.

PURPOSE: The linkage between autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) and neuronal nicotinic acetylcholine receptor has been strongly reinforced by the report of five distinct mutations in the two genes coding for the major brain alpha4beta2 nicotinic acetylcholine (ACh) receptors. As a first step toward understanding the basic mechanisms underlying this genetically transmissible neurologic disorder, we examined the similarities and differences of the functional properties displayed by naturally occurring mutant forms of this ligand-gated channel. METHODS: Functional studies of neuronal nicotinic ACh receptors reconstituted in Xenopus oocytes were designed to analyze the common traits displayed by the different mutations associated with ADNFLE. RESULTS: Coexpression of the control and mutated alleles harboring the alpha4S248F mutation obtained from patient DNAs yielded ACh-evoked currents of amplitude comparable to the control responses but with a higher sensitivity and desensitization to the natural agonist. Alternatively, the other mutants (alpha4L776ins3, alpha4S252L, and beta2V287M) displayed an increased ACh sensitivity without pronounced desensitization. In addition, whereas a reduction of calcium permeability was observed for the mutants (alpha4S248F and alpha4L776ins3), no significant modification of ionic selectivity could be detected in the alpha4S252L mutation. Hence increase in ACh sensitivity is the only common characteristic so far observed between the four naturally occurring mutant receptors investigated. CONCLUSIONS: Analyses of functional properties of four nAChR mutants associated with ADNFLE indicate that a gain of function of these mutant receptors may be at the origin of the neuronal network dysfunction that causes the epileptic seizures. These data are discussed in the context of our latest knowledge of the pyramidal cell function.

Acetylcholine↗
PubMed2002

[Genetic aspects of epilepsy: current knowledge and perspectives].

Rapidly advancing knowledge concerning the genetic aspects of epilepsy have led us to complete a recent article on the subject published in the journal. A contrasting picture is emerging, particularly between symptomatic and idiopathic epilepsy. For symptomatic epilepsy, divers gene products implicated in brain development and neuron survival have been identified. Inversely, for idiopathic epilepsy, the latest discoveries confirm their canalopathic nature. In addition, rapid progress in the field of mendelian inherited epilepsy has pointed out the lack of notable progress concerning common epilepsy with a complex hereditary pattern. These forms are one of the major challenges for genetic analysis of epilepsy.

Animals↗
PubMed2002

[Genetics en epileptology].

Recently, major advances have been obtained concerning the molecular genetic basis of Mendelian inherited epilepsies. Several responsible genes have been identified, leading to a better understanding of the pathophysiology of epilepsy, as well as new approaches in its diagnosis and treatment. However, several questions remain. Indeed, Mendelian epilepsies are rare and few patients are concerned. Despite several lines of evidence demonstrating the involvement of genetic factors in the common forms of epilepsy, no progress has been made in this field. Statistical and molecular strategies adapted to identify susceptibility genes for common epilepsies are now available. But these approaches require large samples of patients and relatives, and a collaborative network will be required for characterisation.

Electroencephalography↗
PubMed2001

A non-radioactive assay for the cAMP-dependent protein kinase activity in rat brain homogenates and age-related changes in hippocampus and cortex.

Cyclic AMP-dependent protein kinase (PKA) activity was involved in a number of brain functions such as cognitive process or aging. The measurement of PKA activity is traditionally based on the use of [(32)P]ATP in phosphorylation of specific protein. Recently non-isotopic PKA assays have been developed, but none has been tested on brain homogenates. This work aimed to adapt a fluorimetric method of PKA activity into a novel assay never applied before in brain homogenate, and to characterize the enzyme activity and ratio in hippocampus and cortex from rats of different ages. Optimal conditions of homogenization and enzyme protection were determined. The method was sensitive and reproducible (intra-assay and interassay variation was 5.0% and 9.0%, respectively). In hippocampal cytosol, PKA activity was 27+/-8 and 80+/-9 nmol/min per mg protein in basal and cAMP-stimulated activity, respectively, and accounted for 80% of total cell PKA activity. The non-PKA activity, assessed by the use of the PKA specific inhibitor (PKI) accounted for 49.0% and 65.0% of endogenous levels in cytosol and membrane, respectively. cAMP-augmenting drugs effects were measured and increase of 53%, 273% and 118% over basal by 10 microM isoproterenol, 100 microM forskolin, 1 microM Sp-AMP, respectively, was observed. With respect to the changes in animal age, PKA activity increased from newborn to the mature rats but decreased in older rats. The PKA ratio was higher in cytosol than in particulate fraction, and was decreased in hippocampal sample from old rats (P<0.05). This last result was interpreted as related to the loss of cognitive capacities in old animals.

Aging↗
PubMed2001

Ion channel variation causes epilepsies.

The discovery of genetically transmissible form of epilepsy associated with a mutation in a gene that codes for a subunit of a ligand-gated channel shined a new light in this field of neurological diseases. Because this gene (CHRNA4) codes for a neuronal nicotinic acetylcholine receptor subunit, functional studies could be designed to evaluate the alterations caused by this mutation. Since this initial observation, five mutations were identified and determination of their functional properties initiated. These experiments were extended to pairwise expression of the control and mutated allele to mimic the heterozygote human genotype. The first common functional trait identified so far, in four of these mutants, is an increased sensitivity to the acetylcholine, suggesting that these mutations may cause a gain of function. An alternative possibility that cannot be excluded is that conditions in the brain are such that these higher responding receptors may be more prone to desensitization. The importance of ionic channels as cause of epilepsies was further demonstrated with the identification of the association between the benign neonatal epilepsy and mutations in genes coding for potassium channel subunits (KCNQ2, KCNQ3). Additional evidences were brought by the identification of mutations in voltage-dependent sodium channels (SCN1A, SCN1B) in a form of generalized epilepsy with febrile seizures.

Acetylcholine↗
PubMed2001

Magnesium involvement in sleep: genetic and nutritional models.

Alterations of peripheral magnesium (Mg) concentration have been reported in association with several behavioral disorders and sleep organization. Blood Mg regulation is under a strong genetic control, whereas brain Mg regulation does not seem to be affected. We have studied peripheral and central levels of Mg and analyzed sleep in two lines of mice selected for low (MGL) and high (MGH) red blood cell (RBC) Mg levels. The same variables were also studied in C57BL/6J mice before and after 3 weeks of Mg deficiency. Whereas blood Mg was highly affected by the selection, brain Mg exhibited only small differences between the two lines. In contrast, Mg deficiency strongly decreased both central and peripheral Mg levels. Sleep analysis indicated that in both models the amount of paradoxical sleep was lower in mice with higher Mg levels. The amplitude of daily variation in sleep and slow-wave sleep delta power was markedly decreased in MGH line. Quantitative electroencephalogram (EEG) analysis also revealed a faster theta peak frequency in MGH mice, irrespective of behavioral states. Central Mg showed significant correlations with the amount of paradoxical sleep and sleep consolidation. However, because the direction of these correlations was not consistent, it is concluded that optimal, (physiological) rather than high or low, Mg levels are needed for normal sleep regulation.

Animals↗
PubMed2001

Suicide attempts and the tryptophan hydroxylase gene.

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme of serotonin synthesis. In this case-control study, we investigated whether the TPH gene was a susceptibility factor for suicidal behavior. Seven polymorphisms spanning the entire gene were studied in a case-control study including 231 individuals who had attempted suicide and 281 controls. Significant associations were found between variants in introns 7, 8 and 9 (chi(2) = 11.2, df = 1, P< 0.0008 for the allele distribution; these loci are in complete linkage disequilibrium) and in the 3' noncoding region (chi(2) = 30.94, P = 0.0014) and suicide attempt. The association was strongest for subjects who had attempted suicide by violent means and who had a history of major depression. No significant association was observed between suicide attempts and polymorphisms in the promoter, intron 1 and intron 3. The results presented here, and those of previous studies, suggest that a genetic variant of the 3' part of the TPH gene may be a susceptibility factor for a phenotype combining suicidal behavior, mood disorder and impulsive aggression.

Adult↗
PubMed2001

Association between violent suicidal behavior and the low activity allele of the serotonin transporter gene.

There is compelling evidence that serotonin system dysfunction is associated with certain behavioral disorders, such as suicidal behavior and impulsive aggression. A functional polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) was recently identified and the presence of the short allele found to be associated with a lower level of expression of the gene, lower levels of 5-HT uptake, suicidal behavior and anxiety-related traits. We genotyped 51 West European Caucasians who had made violent suicide attempts and 139 controls of the same ethnic origin, with no history of suicidal behavior. The frequencies of the S allele and the SS genotype were significantly higher in the violent suicide attempters than in the controls. The odds ratio for the SS genotype vs the LL genotype was 3.63 (95% CI (1.27--10.40)). This suggests that a change in expression of the gene encoding the 5-HT transporter may be involved in violent suicidal behavior.

Adult↗
PubMed2000

Study of the voltage-gated sodium channel beta 1 subunit gene (SCN1B) in the benign familial infantile convulsions syndrome (BFIC).

Benign familial infantile convulsions (BFIC) is a rare autosomal dominant epilepsy syndrome. This syndrome has been recently described in Italian and French pedigrees. Patients present with partial, then generalized seizures, with onset at age three months. The seizures usually spontaneously cease after one year without treatment, leaving no neurological abnormalities. We have mapped BFIC to chromosome 19q in five Italian pedigrees. The sodium channel beta1 subunit gene (SCN1B) maps to this candidate region and has been shown to be involved in one Australian pedigree with generalized epilepsy and febrile seizures "plus" (GEFS +). In this family, a missense mutation in SCN1B cosegregates with the GEFS+ phenotype. BFIC and GEFS+ have clinical features in common, therefore SCN1B is a candidate gene for BFIC. We studied SCN1B exons 1, 2, 3, 4, and 5, using four SSCP methods in 10 Caucasian BFIC probands of Western Europe. We found no exon variants. One variant was identified in intron 5 (IVS5-10C>G), which did not segregate with BFIC and was observed in 9.2% controls. A second variant in intron 5 was identified (IVS5+30G>A). It was rare, as not observed in controls, but not segregating with the BFIC phenotype.

Base Sequence↗
PubMed2000

Identification and analysis of new sequence variants in the human tryptophan hydroxylase (TpH) gene.

The tryptophan hydroxylase (TpH) gene codes for the rate-limiting enzyme in serotonin biosynthesis. It is one of the major candidate genes for psychiatric and behavioral disorders. A polymorphism in TpH intron 7 has been shown to be associated with suicidal attempts, aggressive behavior and psychiatric illnesses. By systematically screening the TpH genomic sequence, we identified and confirmed an earlier report of four variants in the promoter region and localized six new sequence variants, ie two in intron 1b, one in exon 1c, one in intron 8, one in intron 9 and a microsatellite in the 3' region, 5687 bp downstream of the last exon 11. We analyzed these polymorphisms, as well as the one in intron 7, by Single Strand Conformation Analysis, microsatellite or restriction analysis in a collection of 175 West European Caucasian healthy subjects. The four variants in the promoter region are in complete linkage disequilibrium (frequencies of G-T-G-T and T-C-A-G haplotypes are 0. 41 and 0.59, respectively). Deletion of GTT in intron 1b is rare (0. 7%) and so not informative. The rarer allele T of intron 1b polymorphism T3792A has a frequency of 0.34 and is in partial linkage disequilibrium with the more common alleles of intron 7, 8 and 9. The polymorphisms of these three introns are in complete linkage disequilibrium and the frequencies of haplotypes A-T-C and C-C-T are 0.36 and 0.64 respectively. We detected 10 different alleles in the microsatellite localized in the 3' region; allele '194' is in partial linkage disequilibrium with haplotype A-T-C of introns 7, 8, and 9. Analysis of these different polymorphisms will constitute an important tool for future studies between the TpH gene and psychiatric disorders. Molecular Psychiatry (2000) 5, 49-55.

Alleles↗
PubMed2000

Coexistence of dominant and recessive familial amyotrophic lateral sclerosis with the D90A Cu,Zn superoxide dismutase mutation within the same country.

The Cu,Zn superoxide dismutase (Cu,Zn SOD) mutations described in amyotrophic lateral sclerosis (ALS) have, for the most part, a dominant influence. However, while a few cases with a heterozygous D90A mutation have been described in different countries, D90A has been recently proven to be recessively inherited with a common founder effect in Scandinavia. We screened French ALS families for Cu,Zn SOD mutations. The presence of the D90A allele was found in two index-cases, and their families were subsequently studied. In the first family the ALS patients were homozygotes for D90A, while in the second, all ALS patients were heterozygotes. In both families the disease was found to initially involve the lower limbs with slower progression than in sporadic cases, and frequent atypical signs such as paresthesia and urgency of micturition. We determined the D90A allele frequency in controls (n = 200) and sporadic ALS patients (n = 408). No D90A allele was found. This is the first report of coexistence of dominant and recessive families with the D90A Cu,Zn SOD mutation within the same country.

Adult↗
PubMed2000

Blood and brain magnesium in inbred mice and their correlation with sleep quality.

A strong genetic component in the regulation of blood magnesium (Mg) levels has been demonstrated. The regulation and distribution of brain Mg levels, however, have never been assessed. Herein we report on the genetic variation of peripheral and central Mg levels in six inbred strains of mice. In addition, the possible involvement of Mg in sleep regulation was assessed by establishing correlations between Mg and sleep parameters obtained before and after a 6-h sleep deprivation. Although genotype strongly determined blood Mg levels, it did not affect brain Mg, suggesting that central and peripheral Mg are regulated differently. Central Mg displayed a highly structure-specific distribution with frontal cortex having the highest and brain stem the lowest values. Whereas for the amount and distribution of baseline sleep only marginal correlations with Mg were found, Mg contents in four of nine brain structures were highly positively correlated with the length of slow-wave sleep episodes during recovery. This relationship suggests that higher levels of Mg in specific brain sites promote sleep quality as part of a recovery process.

Animals↗