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The first genome-wide association in Alzheimer's disease (AD) suggested that the GAB2 gene rs2373115 polymorphism may be a strong risk factor in APOE ɛ4-carriers. We failed to detect an association of rs2373115 with the risk of developing AD in three populations (totalling 1406 controls and 1749 AD cases) whatever the APOE status, even if we observed a slight tendency for an increase of the GG genotype (OR (GG versus GT + TT) = 1.3, 95% CI 1.0–1.6, p = 0.09) and the G allele frequency (OR = 1.3, 95%CI 1.0–1.6, p = 0.05) in ɛ4-carriers. In addition, the rs2373115 did not modulate the extent of tau phosphorylation in the brain of 89 AD cases. The GAB2 gene is at best a minor genetic determinant of AD.

International audience; Frontotemporal dementia (FTD) is the second most frequent type of neurodegenerative dementias. Mutations in the progranulin gene (GRN, PGRN) were recently identified in FTDU-17, an FTD subtype characterized by ubiquitin-immunoreactive inclusions and linkage to chromosome 17q21. We looked for PGRN mutations in a large series of 210 FTD patients (52 familial, 158 sporadic) to accurately evaluate the frequency of PGRN mutations in both sporadic and familial FTD, and FTD with associated motoneuron disease (FTD-MND), as well as to study the clinical phenotype of patients with a PGRN mutation. We identified nine novel PGRN null mutations in 10 index patients. The relative frequency of PGRN null mutations in FTD was 4.8% (10/210) and 12.8% (5/39) in pure familial forms. Interestingly, 5/158 (3.2%) apparently sporadic FTD patients carried a PGRN mutation, suggesting the possibility of de novo mutations or incomplete penetrance. In contrast, none of the 43 patients with FTD-MND had PGRN mutations, supporting that FTDU-17 and FTD-MND are genetically distinct. The clinical phenotype of PGRN mutation carriers was particular because of the wide range in onset age and the frequent occurrence of early apraxia (50%), visual hallucinations (30%), and parkinsonism (30%) during the course of the disease. This study supports that PGRN null mutations represent a more frequent cause of FTD than MAPT mutations (4.8% vs. 2.9%) but are not responsible for FTD-MND. It also demonstrates that half of the patients with a PGRN mutation in our series had no apparent family history of dementia. Taking this into account, genetic testing should be now considered more systematically, even in patients without obvious familial history of FTD.

Null mutations in the progranulin gene (GRN, PGRN) were recently identified as the causal mechanism underlying frontotemporal dementia (FTD) with ubiquitin-positive brain pathology linked to chromosome 17 (FTDU-17). In a Belgian and French FTD series comprising 332 patients, we reported 13 PGRN null mutations which were mainly nonsense and frameshift mutations resulting in premature stop codons. Here we report in the same patient series three missense mutations of which two (c.743C>T, p.Pro248Leu and c.1294C>T, p.Arg432Cys) were predicted in silico to severely affect protein folding and/or processing leading to PGRN protein haploinsufficiency. In addition, we observed three sequence variations in the 5' regulatory region that might potentially affect PGRN transcription activity. Our findings extend the mutation spectrum in PGRN leading to loss of functional PGRN as the basis for FTD. © 2007 Wiley-Liss, Inc.

We genotyped five polymorphisms, including two polymorphisms with known effects on transcriptional activity, in a large cohort of 427 Alzheimer disease (AD) cases and 472 control subjects. An association between rs463946 (-3102 G/C) and AD was found and was confirmed in a replication sample of a similar size. By contrast, analysis of three recently described rare mutations influencing APP transcription did not confirm their association with AD risk.

International audience; Microdeletions of the 22q11 region, responsible for the velo-cardio-facial syndrome (VCFS), are associated with an increased risk for psychosis and mental retardation. Recently, it has been shown in a hyperprolinemic mouse model that an interaction between two genes localized in the hemideleted region, proline dehydrogenase (PRODH) and catechol-o-methyl-transferase (COMT), could be involved in this phenotype. Here, we further characterize in eight children the molecular basis of type I hyperprolinemia (HPI), a recessive disorder resulting from reduced activity of proline dehydrogenase (POX). We show that these patients present with mental retardation, epilepsy and, in some cases, psychiatric features. We next report that, among 92 adult or adolescent VCFS subjects, a subset of patients with severe hyperprolinemia has a phenotype distinguishable from that of other VCFS patients and reminiscent of HPI. Forward stepwise multiple regression analysis selected hyperprolinemia, psychosis and COMT genotype as independent variables influencing IQ in the whole VCFS sample. An inverse correlation between plasma proline level and IQ was found. In addition, as predicted from the mouse model, hyperprolinemic VCFS subjects bearing the Met-COMT low activity allele are at risk for psychosis (OR = 2.8, 95% CI = 1.04-7.4). Finally, from the extensive analysis of the PRODH gene coding sequence variations, it is predicted that POX residual activity in the 0-30% range results into HPI, whereas residual activity in the 30-50% range is associated either with normal plasma proline levels or with mild-to-moderate hyperprolinemia.

Hyperprolinemia type I (HPI) results from a deficiency of proline oxidase (POX), involved in the first step in the conversion of proline to glutamate. Diverse phenotypes were described in patients with HPI, prior to the identification of the POX gene (PRODH): whereas various patients were asymptomatic, others had neurological and extraneurological defects. The PRODH gene is located in the region deleted in velocardiofacial syndrome (VCFS). Heterozygous and homozygous mutations have been identified in patients with variable hyperprolinemia and various features (patients with schizophrenia, chromosome 22q11 microdeletions and/or neurological defects). A functional study has divided the PRODH missense mutations into three groups: those leading to mild, moderate, or severe reduction of POX activity. In this study, we report four unrelated children with HPI and a homogeneous severe neurological phenotype. We identified biallelic abnormalities in PRODH in these patients that led to severe reduction of POX activity. These included missense and non-sense mutations, deletions of PRODH and a 22q11 microdeletion. Four other children have been reported with severe biallelic PRODH mutations. The phenotype of these eight patients associates early psychomotor development delay with predominant cognitive defects, autistic features and epilepsy. Their values of hyperprolinemia ranged from 400 to 2200 micromol/L. Patients with biallelic PRODH alterations resulting in severely impaired POX activity had an early onset and severe neurological features. Thus, children with this phenotype and those with a microdeletion in chromosome 22q11, especially those with mental retardation and autistic features, should be tested for hyperprolinemia. Hyperprolinemic patients should be screened for PRODH mutations.

International audience; Tauopathies, including Alzheimer's disease (AD), are a group of neurodegenerative disorders characterized by the presence of intraneuronal filamentous inclusions of abnormally phosphorylated tau protein. In AD brains, it has been shown that the level of abnormally phosphorylated tau is higher than in age-matched control brains, suggesting that abnormally phosphorylated tau is resistant to degradation. By using a Drosophila model of tauopathy, we studied the relationship between tau phosphorylation and degradation. We showed that in vivo reduction of proteasome activity results in an accumulation of high-molecular-weight forms of hyperphosphorylated tau. We also found that glycogen synthase kinase (GSK)-3beta-mediated hyperphosphorylated forms of tau are degradable by the proteasomal machinery. Unexpectedly, GSK-3beta inactivation resulted in a very large accumulation of high-molecular-weight species consisting of hyperphosphorylated tau, suggesting that, depending on the kinase(s) involved, tau phosphorylation state affects its degradation differently. We thus propose a model for tauopathies in which, depending on toxic challenges (e.g., oxidative stress, exposure to amyloid peptide, etc.), abnormal phosphorylation of tau by kinases distinct from GSK-3beta leads to progressive accumulation of hyperphosphorylated tau oligomers that are resistant to degradation.

Different duplications of the APP locus have been identified in five families with autosomal dominant early onset Alzheimer's disease (ADEOAD) and Abeta-related cerebral amyloid angiopathy (CAA). This study describes the phenotype of this new entity. Clinical, neuropsychological, imagery and neuropathological data were reviewed. The phenotype was not dependent on the size of the duplication and there was no clinical feature of Down's syndrome. Dementia was observed in all cases; intracerebral haemorrhage (ICH) was reported in 6 (26%) and seizures occurred in 12 (57%) of 21 patients. Age of onset of dementia ranged from 42 to 59 years, ICH from 53 to 64 years and age at death from 46 to 75 years. The neuropathological findings in five cases demonstrated Alzheimer's disease and severe CAA lesions that were reminiscent from those reported in brains of Down's syndrome patients. A striking feature consisted in intraneuronal Abetax-40 accumulation located in the granular cell layer of the dentate gyrus and in the pyramidal cell layer of the Ammon's horn.

We describe the biological consequences on PSEN1 exons 8 or 9 splicing and Abeta peptides production of four PSEN1 mutations associated with a phenotypic variant of Alzheimer disease, which includes cotton wool plaques and spastic paraparesis (CWP/SP). Two of these mutations (c.869-22_869-23ins18 and c.871A > C, p.T291P) are novel mutations located in intron 8 and exon 9, respectively. The c.869-22_869-23ins18 mutation caused exon 9 skipping whereas the c.871A > C (p.T291P) mutation showed only a modest effect on exon 9 skipping. The previously reported E280G and P264L mutations, located in exon 8, had no effect on mRNA splicing. Infection of cells with mutant T291P, E280G, or P264L cDNAs caused a variable increase in secreted Abeta42. We conclude that none of the previously proposed mechanisms, i.e. exceptionally large increases in secreted Abeta42 levels or loss of PSEN1 exons 8 or 9, provides complete explanation of the CWP/SP phenotype.

Contains fulltext : 47983.pdf (Publisher’s version ) (Closed access) Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disease caused by a deficiency of the mitochondrial enzyme 27-sterol hydroxylase (CYP27). We report a 53-year-old man, with an unusual phenotype of CTX. He had xanthomas since adolescence. He had no mental retardation and developed at 44 years a progressive neuropsychiatric phenotype, suggestive of fronto-temporal dementia according to clinical Neary criteria. Cataract and ataxia were absent. Cerebral MRI revealed diffuse hyperintense T2 abnormalities in the supratentorial white matter without cerebellar atrophy or lesions, while Technetium-99m-ECD brain SPECT revealed a severe cerebellar hypoperfusion. Serum cholestanol level was elevated with excessive urinary bile alcohols excretion. Mutation analysis revealed that he was compound heterozygous for two mutations in the CYP27A1 gene: 1016 C > T (exon 5) on one allele and a novel mutation, 1435C > G (exon 8) on the other allele. A follow-up study was conducted to evaluate the effects of chenodeoxycholic acid (CDCA) and simvastatin treatment during 3 years. In spite of this treatment, cognitive functions declined but no other signs of neurological deterioration appeared.

We report duplication of the APP locus on chromosome 21 in five families with autosomal dominant early-onset Alzheimer disease (ADEOAD) and cerebral amyloid angiopathy (CAA). Among these families, the duplicated segments had a minimal size ranging from 0.58 to 6.37 Mb. Brains from individuals with APP duplication showed abundant parenchymal and vascular deposits of amyloid-beta peptides. Duplication of the APP locus, resulting in accumulation of amyloid-beta peptides, causes ADEOAD with CAA.

Background: Autosomal dominant early onset Alzheimer's disease (ADEOAD) is genetically heterogeneous. Mutations of the amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) genes have been identified. Objective: To further clarify the respective contribution of these genes to ADEOAD. Methods: 31 novel families were investigated. They were ascertained using stringent criteria (the occurrence of probable or definite cases of Alzheimer's disease with onset before 60 years of age in three generations). All cases fulfilled the NINCDS-ADRDA criteria for probable or definite Alzheimer's disease. The entire coding regions of PSEN1 and PSEN2 genes and exons 16 and 17 of APP gene were sequenced from genomic DNA Results: PSEN1 mutations, including eight previously unreported mutations, were detected in 24 of the 31 families, and APP mutations were found in five families. In this sample, the mean ages of disease onset in PSEN1 and APP mutation carriers were 41.7 and 51.2 years, respectively. Conclusions: Combining these data with previously published data, yielding 65 ADEOAD families, 66% of the cases were attributable to PSEN1 mutations and 16% to APP mutations, while 18% remained unexplained.

We report a familial disorder occurring in three patients that presented as frontotemporal dementia (FTD). A neuropathological study was performed in a 58-year-old patient, who developed FTD 2 years prior to the onset of motor neuron disease (MND), and died at age 62. Lesions indicative of associated MND were observed: neuronal loss in the anterior horns of the spinal cord, Bunina bodies, axonal spheroids, degeneration of the pyramidal tracts, and of FTD: decreased neuronal density and laminar microvacuolation of layers II and III in the frontal and temporal cortex. Ubiquitin-only-immunoreactive changes were found in the spinal cord and medulla, but were absent from the temporal and frontal cortex. There were also widespread deposits of various neuronal and glial inclusions containing abnormally phosphorylated tau protein, the Western blotting pattern of which was characterized by two major bands of 64 and 69 kDa. There were no abnormalities of the entire coding sequences of microtubule-associated protein tau (MAPT) and copper-zinc superoxide dismutase (SOD(1)) genes. Our results suggest that FTD associated with MND can be caused by a larger spectrum of neuropathological lesions than commonly accepted.

Whether an alteration of dopaminergic function exists in schizophrenia or not, it is tempting to speculate that a genetic abnormality of dopamine (DA) receptors--e i ther structural or affecting gene expression--might play a causative role in the pathogenesis of schizophrenia. Recently, five subtypes of DA receptors were characterized and the human genes corresponding to these different subtypes were cloned and assigned to chromosomes 5q35.1(Dl), l lq22.23(D2), 3q13.3(D3), l lp15.5(D4), and 4p16.1 (D5), respectively (Grandy et al 1989, 1990, 1992; LeConiat et al 1991; Gelernter et al 1992; see Campion et al, 1994). Each of these genes can be regarded as a candidate for a genetic defect in schizophrenia; however, except for a mutation described for the DA D4 receptor in delusional disorder (Catalano et al 1993), no linkage or association between schizophrenia and any of these genes has so far been found (Moises et al 1991; Campion et al 1994; Sabat6 et al 1994; Macciardi et al 1994; Ravindranathan et al 1994). This could be due to the use of incorrect genetic parameters in linkage analyses, or to the etiologic heterogeneity of schizophrenia, but also to misdiagno

The D14S43 marker is closely linked to the major gene for early onset autosomal dominant Alzheimer's disease on chromosome 14. Allelic frequencies at the D14S43 locus were compared in 113 familial and isolated cases of early onset Alzheimer's disease (

Myoclonus-dystonia syndrome (MDS) is an autosomal dominant disorder characterized by myoclonic and dystonic muscle contractions, associated with psychiatric manifestations. MDS is usually considered as a benign disease. In most of the families, MDS is linked to chromosome 7q21 and mutations within epsilon-sarcoglycan (SGCE) gene have been recently described. We report a MDS family with a severe and heterogeneous phenotype, including myoclonus with important functional impact and several psychiatric features, characterized by obsessive-compulsive disorder, depression, and anxiety. This phenotype was shown to be associated with a novel truncating mutation located within exon 4 of SGCE.

Recently, a single nucleotide polymorphism that results in an amino acid change (Q7R) was identified in a previously undescribed gene, named saitohin, nested within the tau gene. We analyzed the distribution of this polymorphism in 499 patients with Alzheimer's disease, 91 patients with frontotemporal dementia, and 402 controls. This polymorphism was in complete disequilibrium with the well-defined extended tau haplotype. We failed to replicate the association between the RR genotype and late-onset Alzheimer's disease, but we found a trend toward an association between the QQ genotype and frontotemporal dementia. Thus, the saitohin Q allele, which is a novel determinant of the tau H1 haplotypes, might represent a causative factor involved in the determinism of several tauopathies.

The increased prevalence of schizophrenia among patients with the 22q11 interstitial deletion associated with DiGeorge syndrome has suggested the existence of a susceptibility gene for schizophrenia within the DiGeorge syndrome chromosomal region (DGCR) on 22q11. Screening for genomic rearrangements of 23 genes within or at the boundaries of the DGCR in 63 unrelated schizophrenic patients and 68 unaffected controls, using quantitative multiplex PCR of short fluorescent fragments (QMPSF), led us to identify, in a family including two schizophrenic subjects, a heterozygous deletion of the entire PRODH gene encoding proline dehydrogenase. This deletion was associated with hyperprolinemia in the schizophrenic patients. In addition, two heterozygous PRODH missense mutations (L441P and L289M), detected in 3 of 63 schizophrenic patients but in none among 68 controls, were also associated with increased plasma proline levels. Segregation analysis within the two families harboring respectively the PRODH deletion and the L441P mutation showed that the presence of a second PRODH nucleotide variation resulted in higher levels of prolinemia. In two unrelated patients suffering from severe type I hyperprolinemia with neurological manifestations, we identified a homozygous L441P PRODH mutation, associated with a heterozygous R453C substitution in one patient. These observations demonstrate that type I hyperprolinemia is present in a subset of schizophrenic patients, and suggest that the genetic determinism of type I hyperprolinemia is complex, the severity of hyperprolinemia depending on the nature and number of hits affecting the PRODH locus.

To date, allele 4 of the apolipoprotein E gene is the only risk factor that has been robustly associated with Alzheimer's disease (AD). Identification and molecular characterization of other risk factors is of great interest. The insulin degrading enzyme (IDE) is an attractive candidate gene since: (i), previous studies have identified a possible role that IDE plays in the degradation and clearance of human amyloid beta from migroglial cells and neurons; and (ii), this gene is located on chromosome 10q23-q24, a region in which a susceptibility locus for AD has recently been mapped. In the present study, we have assessed whether IDE is a potential risk factor for AD. Two intronic single nucleotide polymorphisms (SNPs) were genotyped in a case-control study including 388 French individuals. No association between these SNPs and AD was detected.

Background Recent studies have shown an association between an extended tau haplotype (H1) that covers the entire human tau gene and progressive supranuclear palsy or, more inconsistently, other neurodegenerative disorders, such as corticobasal degeneration, Parkinson disease, Alzheimer disease, and frontotemporal dementia (FTD). In addition, disease-causing mutations in the tau gene on chromosome 17 have been detected in some families with autosomal dominant FTD and parkinsonism. In FTD, the pathological accumulation of the microtubule-associated protein tau suggests that the tau gene may be a genetic risk factor for this disorder. Objective To confirm or refute the association between the H1 haplotype or the H1H1 genotype of the tau gene and FTD. Design Case-control study. Setting Neurology departments of 12 French university hospitals. Participants One hundred unrelated patients with FTD and 79 controls. Methods Tau genotype (contiguous polymorphisms in exons 1, 7, and 13 and in intron 9 used to reconstruct the extended haplotypes H1 and H2). Clinical examination, psychometric testing, laboratory tests, computed tomography and magnetic resonance imaging, single-photon emission computed tomography, and electroencephalography for patients with FTD. Results The H1H1 genotype was significantly overrepresented in patients with FTD compared with controls (62% vs 46%; P = .01, 1-sided; odds ratio adjusted for age and sex, 1.95). After stratification according to apolipoprotein E ( APOE ) genotype, we found a significant interaction between APOE and tau genotypes ( P = .03). Conclusions This study of the largest series of patients with FTD confirms the primary role of tau in FTD and establishes that the H1 haplotype of the tau gene and the E2 allele of APOE interact by an unknown mechanism that increases the risk of FTD.

Introduction The relevance of the cerebrospinal fluid (CSF) biomarkers for the diagnosis of Alzheimer’s disease (AD) and related disorders is clearly established. However, the question remains on how to use these data, which are often heterogeneous (not all biomarkers being pathologic). The objective of this study is to propose to physicians in memory clinics a biologic scale of probabilities that the patient with cognitive impairments has an Alzheimer’s disease (AD) pathologic process. Methods For that purpose, we took advantage of the multicenter data of our Paris-North, Lille, and Montpellier (PLM) study, which has emerged through the initial sharing of information from these memory centers. Different models combining the CSF levels of amyloid-β 42, tau, and p-tau(181) were tested to generate categories of patients with very low (75%), and very high predictive values (>90%) for positive AD. In total, 1,273 patients (646 AD and 627 non-AD) from six independent memory-clinic cohorts were included. Results A prediction model based on logistic regressions achieved a very good stratification of the population but had the disadvantages of needing mathematical optimization and being difficult to use in daily clinical practice. Remarkably, a simple and intuitive model based on the number (from zero to three) of three pathologic CSF biomarkers resulted in a very efficient predictive scale for AD in patients seen in memory clinics. The scale’s overall predictive value for AD for the different categories were as follows: class 0, 9.6% (95% confidence interval (CI), 6.0% to 13.2%); class 1, 24.7% (95% CI, 18.0% to 31.3%); class 2, 77.2% (95% CI, 67.8% to 86.5%); and class 3, 94.2% (95% CI, 90.7% to 97.7%). In addition, with this scale, significantly more patients were correctly classified than with the logistic regression. Its superiority in model performance was validated by the computation of the net reclassification index (NRI). The model was also validated in an independent multicenter dataset of 408 patients (213 AD and 195 non-AD). Conclusions In conclusion, we defined a new scale that could be used to facilitate the interpretation and routine use of multivariate CSF data, as well as helping the stratification of patients in clinical research trials.

Several observations suggest that neurotoxicity in Alzheimer's disease (AD) can be partly attributed to beta-amyloid (Abeta) and senile plaques. Recent work has suggested that the FISH (five SH3 domains) adapter protein and ADAM12 (a disintegrin and metalloprotease) may mediate the neurotoxic effect of Abeta. Both genes are located on chromosome 10, within a region linked to AD (for SH3PXD2A) or nearby (for ADAM12). A recent study reported a statistically significant interaction between 2 variants of these genes (rs3740473 for SH3PXD2A and rs11244787 for ADAM12) with respect to the risk of developing AD. With a view to replicating this observation, we genotyped the two SNPs in four European case-control cohorts of Caucasian origin (1913 cases and 1468 controls) but were unable to confirm the initial results.

The apolipoprotein E (APOE, gene; apoE, protein) isoforms are associated with differential risk of Alzheimer's disease (AD). An additional involvement of APOE promoter polymorphisms in AD risk has recently been suggested by several studies. Indeed, three polymorphisms of the APOE regulatory region (-219 G/T, -427 C/T and -491 A/T) have been found associated with AD even after adjustment on the apoE status. We analysed these three promoter region polymorphisms in a large French case-control study (388 AD cases and 386 controls). We found that the -427 T and -491 A alleles were associated with an increased risk of developing AD, but not the -219 G/T alleles. However, a strong linkage disequilibrium was observed between the alleles of these promoter region polymorphisms and the APOE coding region alleles. We therefore retested association after adjustment on apoE status and found that the sole association which remained significant was the association with the -427 T allele. The alpha level was equal to 0.03 (0.09 after Bonferroni correction for multiple comparisons). Analysis of promoter haplotypes also yielded non-significant results. Thus our study does not reinforce the hypothesis of an independent involvement of the APOE promoter region polymorphisms in AD risk.

Determination of the effects of presenilin 1 (PSEN1) mutations, involved in autosomal dominant early-onset Alzheimer's disease (ADEOAD), on the interaction between PSEN1 and binding proteins is essential to determine which interactions are involved in Alzheimer's disease (AD) pathogenesis. The PSEN1 binding protein glycogen synthase kinase-3 beta (GSK-3 beta) has been considered as a key protein in AD pathogenesis since GSK-3 beta phosphorylates tau and hyperphosphorylated tau is a main component of neurofibrillary tangles associated to AD. We show here, using surface plasmonic resonance, that the pathogenic L392V mutation, identified in a large French ADEOAD pedigree including 39 affected members, leads to a decreased affinity to GSK-3 beta. We conclude therefore that the increase of affinity of PSEN1 to GSK-3 beta reported in previous studies is not a common effect of pathogenic mutations associated to ADEOAD.

Introduction Les ataxies spinocerebelleuses (SCA) sont des maladies heterogenes par leur phenotype clinique et leur determinisme genetique. L’ataxie cerebelleuse est associee dans la majorite des cas a d’autres signes neurologiques (syndrome pyramidal, demence, signes ophtalmologiques). Vingt huit genes ou loci sont actuellement impliques dans les SCA autosomiques dominantes (AD) et trente deux dans les SCA autosomique recessifs (AR). Nous rapportons 4 cas associant ataxie cerebelleuse et demence. Materiel et methode Etude neuropathologique et genetique (genes SCA 1, 2, 3, 6, 7, DRPLA, TTBK2, PSEN1, FMR1, IT15 et MAPT). Resultats Deux familles avec un mode de transmission AD (F1, F2) et une (F3) avec une possible transmission AR. Dans F1, l’ataxie du propositus debutait a 48 ans, la demence a 62 ans. Le pere etait ataxique et dement, le petit-fils etait ataxique. Dans F2, l’ataxie et la demence debutaient a 50 ans. La mere etait atteinte de cecite et decedee a 50 ans, le frere avait un retard mental et une cecite. Dans F3, ataxie, syndrome extrapyramidal et demence debuterent chez 2 soeurs a 47 et 53 ans. L’etude anatomopathologique retrouvait dans les 4 cas, une atrophie diffuse cerebrale, predominant dans les regions infratentorielles. Il existait une perte neuronale corticale et dans les noyaux gris centraux, une gliose de la substance blanche, et de nombreuses inclusions intra-neuronales associees a des astrocytes tau positifs, dont la repartition topographique etait celle des paralysies supra-nucleaires progressives. Chez un patient, des lesions de type Alzheimer etaient associees. L’etude genetique est actuellement negative. Conclusion Quatre cas familiaux de tauopathie avec ataxie et demence dont la cause genetique est indeterminee.

Autosomal dominant early-onset Alzheimer's disease results mainly from mutations of the presenilin 1 (PSEN1) gene, which codes for an integral membrane protein of 467 amino acids. The hydrophilic loop (amino acids 263-407) of PSEN1, in which many pathogenic mutations have been localized, appears to be crucial for the protein function since it includes the binding domains to different PSEN1 partners. Using circular dichroism (CD) we analyzed the structural effects of the pathogenic L392V mutation and compared them with those of the E318G substitution. This study revealed that, the L392V mutation, in a phospholipidic medium which mimics the in vivo membrane environment, reduces the alpha helix content of the PSEN1 loop, whereas the E318G substitution, considered as a polymorphism, does not. These results suggest that the pathogenic effect of some PSEN1 mutations within the hydrophilic loop could be the alteration of the interaction to the different binding proteins through a disruption of the secondary structure.

SummaryTo determine the prevalence of early-onset Alzheimer disease (EOAD) and of autosomal dominant forms of EOAD (ADEOAD), we performed a population-based study in the city of Rouen (426,710 residents). EOAD was defined as onset of disease at age

Presenilin 1 (PS1) mutations account for the majority of early-onset dominant cases of familial Alzheimer's disease. Presenilins (PSs) are located in many intra-cellular compartments such as the endoplasmic reticulum, Golgi apparatus, nuclear region and vesicular structures. These proteins include from seven to nine putative transmembrane domains, with the N- and C-terminal ends and a large hydrophilic loop orientated towards the cytoplasm. We report an interaction between the human PS1 or PS2 hydrophilic loop and Rab11, a small GTPase belonging to the Ras-related superfamily. Interaction domains were mapped to codons 374-400 for PS1 and to codons 106-179 for Rab11, a region including the fourth GTP-binding domain. Considering the implication of Rab proteins in vesicular transport pathways, the PS-Rab11 inter-action suggests that PSs might be involved in amyloid precursor protein vesicular routing.

Presenilin 1 (PSEN1) mutations account for the majority of cases of autosomal dominant early onset Alzheimer’s disease (ADEOAD).1 2 The PSEN1 gene encodes for a 467 amino acid transmembrane protein which functions as a subunit of the γ-secretase complex that cleaves amyloid precursor protein to generate the Aβ amyloid peptide. More than 160 different mutations have been reported (www.molgen.ua.ac.be/ADMutations) with a great diversity of phenotypes: very early age of onset, early myoclonus seizures, parkinsonism, spastic paraplegia associated with “cotton wool plaques” or rare frontotemporal variant of AD. Ataxia has been rarely described during the course of ADEOAD caused by PSEN1 mutations. Ataxia and psychiatric signs were recently reported as initial symptoms associated with a PSEN1 Ser170Phe mutation.3 We report three patients from the same family with early prominent severe ataxia associated with dementia caused by a novel PSEN1 mutation. ### Patient III2 A 35-year-old woman (fig 1) was seen for writing and balance difficulties, with memory complaints. All three symptoms occurred contemporaneously 1 year previously. Examination showed severe ataxia with instability, marked dysarthria and dysmetria with intention tremor, brisk reflexes and rare myoclonus. Neuropsychological assessment, including Mini Mental Scale (score 22/30), Grober and Buschke Learning Test (GBVLT) (delayed total …

Missense mutations in the genes encoding amyloid precursor protein (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2) have been found to cause some forms of autosomal dominant early onset Alzheimer disease (AD). Autosomal dominant point mutations in the APP gene are associated with β-amyloid peptide related cerebral amyloid angiopathy (CAA) and AD.1 Duplications of the APP locus on chromosome 21 have recently been reported to be associated with a phenotype similar to that caused by point mutations in the APP gene, including progressive AD and strokes and intracerebral haemorrhage (ICH) of variable frequency.2–4 The neuropathological findings have been consistent with a diagnosis of definite AD according to the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD). The most prominent feature in all cases has been severe CAA in the leptomeningeal vessels together with superficial and deep intraparenchymatous small arteries, capillaries and venules. Figure 1 Detection of amyloid precursor protein (APP) duplication by quantitative multiplex PCR of short fluorescent fragments (QMPSF). The electropherogram of the affected subject (in red) was superimposed on that of a normal individual (in blue) by adjusting the peaks obtained from the control amplicon PCBD2 located on chromosome 5 to the same level. The vertical axis shows fluorescence in arbitrary units and the horizontal axis indicates the size of the amplicons in base pairs. Arrows indicate heterozygous duplication of the amplicons, as detected by a 1.5 fold heightening of the corresponding peaks. This QMPSF covers four genes located at 21q21: MRPL39 , GABPA , APP and CYYR1 . We have previously described detailed clinical features of a four generation Finnish family, including 14 …

Introduction La maladie d’Alzheimer (MA) et la demence a corps de Lewy (DCL) sont deux entites a part entiere mais dont le diagnostic differentiel peut parfois etre difficile, comme l’atteste notre observation. Observations Clinique : Mme P. (05-143), sans antecedent neurologiques, presenta un syndrome dementiel, debutant a 44 ans par un syndrome aphaso-apraxo-agnosique associe a une desorientation spatiale, d’evolution progressive et rapide en 10 ans. Apres 7 ans d’evolution apparut un syndrome extrapyramidal avec hallucinations, des chutes et des fluctuations comportementales. Absence d’amelioration sous neuroleptiques et apparition de myoclonies en fin de vie. Sa mere et une tante maternelle etaient decedees d’une MA ayant debute a respectivement 48 et 60 ans.Anatomopathologie : Lesions d’angiopathie amyloide severes diffuses intraparenchymateuses et meningees avec predominance de depots d’A b40, dans les secteurs infra et supra-tentoriels, associees a des lesions de type Alzheimer intenses (anticorps anti-Tau) et diffuses (criteres du CERAD). La plupart des lesions de degenerescence neurofibrillaire et des plaques sont ubiquitinees. Negativite des depots A b40 et A b42 intraneuronale Le marquage de l’a — synucleine montre de tres nombreux corps de Lewy diffus realisant l’aspect d’une DCL (criteres de Mac Keith). Genetique : Presence d’une microduplication du gene de l’APP (chromosome 21). Discussion Deux hypotheses sont evoquees: – une MA (syndrome aphasoapraxoagnosique precoce, anatomopathologie, genetique) ; – une DCL (analyse anatomopathologique, syndrome extrapyramidal, hallucinations et fluctuations a un stade precoces pour une MA). La microduplication du gene de l’APP est un syndrome recemment decrit dans 6 familles francaises, exprimant deux phenotypes (MA pure et AVC hemorragiques). Conclusion Ce tableau pose la question du recouvrement des criteres cliniques et anatomopathologiques chez un meme patient, alors que la microduplication du gene de l’APP etaye l’hypothese amyloide de la physiopathologie de la MA.

To investigate the relationship among risk for Alzheimer disease (AD), familial aggregation of AD, and the apolipoprotein E (apoE) epsilon4 allele in first-degree relatives of probands with AD and known apoE genotype.Two hundred ninety subjects fulfilling the criteria of the National Institute of Neurological Communicative Disease and Stroke-Alzheimer's Disease and Related Disorders Association for probable AD were ascertained from March 1, 1992, to December 31, 1996, through consecutive admissions in several university hospitals.Family data were collected on 1176 first-degree relatives (parents and siblings), aged 40 to 90 years. Most living relatives underwent a clinical examination, whereas we relied on family history for clinical data for deceased or unavailable relatives. First, we conducted standard survival analyses to estimate cumulative lifetime risk (LTR) for AD among relatives and to investigate for sex and apoE genotype effects on LTR. Then, we assessed to what extent clustering of secondary AD could be explained by the apoE epsilon4 allele by deriving the expected proportions of relatives with 0, 1, or 2 apoE epsilon4 alleles conditionally on the proband's genotype.Cumulative LTR for AD among first-degree relatives increased significantly with the number of epsilon4 alleles present in the proband. By 90 years of age, LTRs in relatives of probands with epsilon3/epsilon3, epsilon3/epsilon4, and epsilon4/epsilon4 genotypes were 29.2%, 46.1%, and 61.4%, respectively. Significant sex-by-apoE genotype interaction effects on LTR were observed. Women had about a 2-fold higher risk for AD than men among relatives of epsilon4 carriers but not among relatives of non-epsilon4 carriers. The predicted proportion of epsilon4 carriers in relatives of probands with epsilon3/epsilon3 genotype remains about 50% lower than the corresponding LTR for AD, indicating that familial clustering of AD is largely due to other factors than the apoE epsilon4 allele. Although aggregation of AD in families of probands with the epsilon4 allele is more prominent, we estimated that AD would not develop in about 30% of female and up to 60% of male relatives carrying at least 1 epsilon4 allele, even by 90 years of age.Our results support the hypothesis that the apoE epsilon4 allele enhances AD susceptibility, but putative factors enhancing risk for AD remain to be found.

SummaryThe aim of this study was to test that deficit (D) schizophrenic patients as defined by Carpenter et al had a higher prevalence of family history of schizophrenia but less obstetric complications than non-deficit (ND) patients. A lower rate of obstetric complications but an excess of schizophrenic and a higher rate of alcoholism family antecedents in 18 D patients compared to 23 ND patients were found. These results could suggest that there is a different weight of genetic and early environmental factors in D and ND patients.

468 s’expliquer par un besoin minimal en fer de la levure qui peut etre assure par la mitoferrine2 (de meme, dans les cellules non-erythroides du poisson, le transfert mitochondrial du fer est probablement assure par la mitoferrine2). En revanche, les quantites importantes de fer necessaires au cours de la differenciation erythroide semblent pouvoir n’etre suppleees que par la mitoferrine1. Enfin, la derniere serie d’experiences demontrant l’activite de la mitoferrine dans l’import de fer mitochondrial a utilise des clones stables de levure mrs3/4 exprimant un gene rapporteur codant pour une enzyme mitochondriale dont l’activite est dependante du fer. Les auteurs montrent que l’activite de cette enzyme est reduite de moitie dans la souche mutante mrs3/4. Apres transfection de l’ADNc de la mitoferrine de poisson, cette activite retourne a la normale, indiquant bien que la mitoferrine a permis au fer de rentrer dans la mitochondrie et, par la meme, d’activer l’enzyme. En conclusion, ce travail a permis de caracteriser la proteine responsable du transport du fer mitochondrial, la mitoferrine1 pour les precurseurs erythroides et, probablement, la mitoferrine2 pour les cellules non-erythroides. Ce transport de fer est crucial pour la production mitochondriale de l’heme, composant essentiel du metabolisme du fer. En effet, on retrouve l’heme non seulement dans l’hemoglobine du globule rouge mais egalement dans la myoglobine, la neuroglobine ainsi que toutes les enzymes a groupement prosthetique (catalase, peroxydase, cytochrome, nitric oxid synthase...). Il y a fort a parier que tout dereglement de la mitoferrine soit responsable de pathologie(s) chez l’homme. ◊ Gene fishing in zebrafish : identification of the iron mitochondrial transporter

The pathogenesis of schizophrenia might involve abnormal development of the human brain. Interleukin-1 beta is a cytokine implicated in the development of the central nervous system and therefore its gene is a candidate gene in schizophrenia. Polymorphisms within the coding sequence and the 3'UTR of the IL1 beta gene were searched for using PCR-SSCP. Two polymorphisms, 1B-175/1B-173 and 1B-1765/1B-1763 were found in addition to the previously published TaqI site. Furthermore, a mutant was found in codon 106 (exon 5) of the IL1 beta gene located next to the published polymorphism at the TaqI site and abolishing this site. This novel mutation encodes an Asp in place of an Asn and was only observed in one patient in our French population. Association studies were conducted with the polymorphisms 1B-175/1B-173 and TaqI. There was no allelic or genotypic association between either of the two polymorphisms and schizophrenia. In our population, there is no evidence that the IL1 beta gene is involved in schizophrenia.

The apolipoprotein E (ApoE)-epsilon4 allele is associated in a dose dependent manner to an increased risk for Alzheimer's disease. However, the ApoE-epsilon4 allele effect does not account for all patients with Alzheimer's disease, and the existence of other genetic risk factors has been postulated. Kamboh et al reported an association between Alzheimer's disease and the A allele of alpha1-antichymotrypsin (Aact) gene, which was not confirmed in a larger series more recently analysed. The ApoE and Aact genotypes were analysed in 314 patients with Alzheimer's disease and 173 healthy controls, confirming the dose dependent effect of the ApoE-epsilon4 allele. Nevertheless, even using odds ratios adjusted for age and sex, there was no significant effect of the Aact genotype on Alzheimer's disease or on the ApoE-epsilon4 allele associated risk for Alzheimer's disease.

We examined whether there are clinical or biological differences in chronic schizophrenic patients sharing a rare variant allele (a perfect ten tetranucleotide repeats allele of the human TH01 microsatellite) in the tyrosine hydroxylase (TH) gene. For that purpose, clinical parameters (PANSS subscores) and plasma measurements (homovanillic acid and 3-methoxy-4-hydroxy-phenylglycol (MHPG)) were analyzed in five schizophrenic patients sharing the rare allele and 19 schizophrenic patients who did not possess this allele. The mean concentration of plasma HVA and plasma MHPG were significantly lower in the group of schizophrenic patients sharing the rare allele. No other group differences were observed between both groups. These results suggest that this TH gene polymorphism may be associated with disturbances of the catecholaminergic pathway.

We have identified a novel Alzheimer's disease family in which affected subjects had a very young age of onset (range 29-35 years). Neuropathological confirmation of the diagnosis was obtained for one patient. Molecular analysis shows that within this family the disease results from a missense mutation at codon 235 of the presenilin 1 (PS-1) gene. Two patients had exhibited generalized tonico-clonic seizures several years before the onset of dementia. Whether this particular clinical feature is a consequence of the PS-1 mutation remains to be established. The Leu235Pro mutation is, to our knowledge, the PS-1 mutation associated with the youngest age of AD onset, which suggests that it has a drastic effect on PS-1 function.

Monoamine oxidases (MAO) A and B, which are encoded by two distinct genes located on the human X chromosome, are both involved in the oxidative metabolism of dopamine. Decreased levels of platelet MAO-B activity has been reported in patients with schizophrenia and genetic variation in MAO activity had been proposed as a significant factor in the etiology of this disease. We carried out an association study using two intragenic polymorphisms within the MAO-A and MAO-B genes in 110 schizophrenic patients and 87 control subjects. For each polymorphic marker, no significant difference in allelic frequencies was observed between patients and controls. Nevertheless, a trend toward an association between allele 1 of the MAO-B gene and paranoid schizophrenia was found. Our results do not support the hypothesis that inherited variants of MAO genes might play a major role in a genetic predisposition to schizophrenia. Since several previous reports found a low MAO-B platelet activity in patients with paranoid schizophrenia, the identification of polymorphisms related to enzyme activity would be useful.

Missense mutations in the presenilin 2 (PS-2) gene on chromosome 1 were sought by direct nucleotide sequence analysis of the open reading frame of 60 pedigrees with familial Alzheimer's disease (FAD). In the majority of these pedigrees, PS-1 and beta-amyloid precursor protein (beta APP) gene mutations had been excluded. While no additional PS-2 pathogenic mutations were detected, four silent nucleotide substitutions and alternative splicing of nucleotides 1338-1340 (Glu325) were observed. Analysis of additional members of a pedigree known to segregate a Met239Val mutation in PS-2 revealed that the age of onset of symptoms is highly variable (range 45-88 years). This variability is not attributable to differences in ApoE genotypes. These results suggest (i) that, in contrast to mutations in PS-1, mutations in PS-2 are a relatively rare cause of FAD; (ii) that other genetic or environmental factor modify the AD phenotype associated with PS-2 mutations; and (iii) that still other FAD susceptibility genes remain to be identified.