Expression Profiles of SIRT1 and APP Genes in Human Neuroblastoma SK-N-SH Cells Treated with Two Epigenetic Agents

In our previous studies, significant hypermethylation of the sirtuin 1(SIRT1) gene and demethylation of the b-amyloid precursor protein(APP) gene were found in patients with Alzheimer's disease(AD) compared with the normal population. Moreover, the expression of SIRT1 was significantly decreased while that of APP was increased in AD patients. These results indicated a correlation of DNA methylation with gene expression levels in AD patients. To further investigate the epigenetic mechanism of gene modulation in AD, we used two epigenetic drugs, the DNA methylation inhibitor 5-aza-20-deoxycytidine(DAC) and the histone deacetylase inhibitor trichostatin A(TSA), to treat human neuroblastoma SK-N-SH cells in the presence of amyloid b-peptide Ab25–35(Ab25–35). We found that DAC and TSA had different effects on the expression trends of SIRT1 and APP in the cell model of amyloid toxicity. Although other genes, such as microtubule-associated protein s, presenilin 1, presenilin 2, and apolipoprotein E, were up-regulated after Ab25–35treatment, no significant differences were found after DAC and/or TSA treatment. These results support the evidence in AD patients and reveal a strong correlation of SIRT1/APP expression with DNA methylation and/or histone modification, which may help understand the pathogenesis of AD.     

Cognitive function correlations with apolipoprotein Eε4 single nucleotide polymorphism in 1 000 elderly patients following general anesthesia A randomized controlled study

BACKGROUND: Cognitive dysfunction occurs in elderly patients following general anesthesia, and this might be associated with genetics. Studies have shown that theε4 allele gene is closely associated with senile dementia.OBJECTIVE: To compare and analyze the correlations between cognitive dysfunction and single nucleotide polymorphism of apolipoprotein E (ApoE) following inhaJation or intravenous anesthesia.DESIGN, TIME AND SETTING: A randomized, controlled study was performed. The patients were recruited from the Department of Anesthesia, Second Affiliated Hospital, Medical College, Xi'an Jiaotong University, China between May 2005 and December 2008. Genetic analyses were conducted at the Departments of Neuroanatomy and Forensic Medicine, Medical College, Xi'an Jiaotong University, China.PARTICIPANTS: A total of 1 000 patients of ASA Ⅰ-Ⅱ grade, without genetic connection, were enrolled in this study, comprising 520 males and 480 females, aged (70.1±4.6) years and weighing (57.3±7.5) kg. No patients suffered from cognitive dysfunction.METHODS: The patients were equally and randomly divided into intravenous anesthesia and gas anesthesia groups. Total intravenous anesthesia and inhaled anesthesia were used. Genomic DNA from whole blood was extracted. The ApoE gene was amplified by PCR. Restriction fragment length polymorphism of ApoE gene was analyzed. Cognitive function was evaluated by Mini-Mental State Examination (MMSE). Patients scoring < 25 points were diagnosed with cognitive dysfunction.MAIN OUTCOME MEASURES: Correlation of ApoE gene frequency and ApoEε4 allele to MMSE scores was measured.RESULTS: MMSE scores in patients from the gas anesthesia group significantly decreased 3 days after surgery, compared with the intravenous anesthesia group. The proportion of patients that scored < 25 points was significantly greater in the gas anesthesia group compared with the intravenous anesthesia group 3 days after surgery. Reduced MMSE scores closely correlated with expression of the ApoEε4 allele in the gas anesthesia group (odds ratio=2.83; 95% confidence interval was 1.25-6.39, P<0.05). However, decreased MMSE scores did not closely correlated with expression of the ApoEε4 allele in the intravenous anesthesia group (odds ratio=0.96; 95% confidence interval was 0.37-2.39, P>0.05).CONCLUSION: Results demonstrated a correlation between cognitive dysfunction and ApoE single nucleotide polymorphism in elderly patients after gas anesthesia. However, no relationship between cognitive dysfunction and ApoE single nucleotide polymorphism was determined in elderly patients following intravenous anesthesia. Therefore, elderly patients, especially those expressing the ApoEε4 gene, should be cautiously exposed to gas anesthesia.     

Association of Nurr1 gene mutations with Parkinson’s disease in the Han population living in the Hubei province of China

Nurr1 defects could in part underlie Parkinson’s disease pathogenesis,and Nurr1 gene polymorphism has been found in Caucasian patients with Parkinson’s disease.In this study,heteroduplex technology was applied to compare the DNA sequences of eight exons of Nurr1 among 200 sporadic Parkinson’s disease patients and 200 healthy controls in the Han population in the Hubei province,China.One allele amplified from exon 3 of Nurr1 was polymorphic in five Parkinson’s disease patients(2.5%,5/200),and two individuals had a polymorphic allele amplified from exon 2 (1%,2/200).The anomalous electrophoresis fragment in exon 3 of Nurr1 gene contained a 709C/A missense mutation,and a polymorphic single nucleotide polymorphism at 388G/A was identified in exon 2.Compared with the control group,the Nurr1 gene expression level in the Parkinson’s disease group was decreased,and the Nurr1 gene expression levels in Parkinson’s disease patients carrying the polymorphisms at exons 2 and 3 were significantly decreased.Our data indicate that the single nucleotide polymorphism 388G/A in exon 2 and the 709C/A missense mutation in exon 3 of the Nurr1 gene in the Chinese population might affect the pathogenesis of Parkinson’s disease.     

遗传性痉挛性截瘫一家系的临床特点与遗传学分析

Objective To study the clinical and genetic features of a family with hereditary spastic paraplegia(HSP).Methods The patients were from a large Linyi family.Five members were clinically diagnosed with HSP according to Harding's criteria Blood samples were collected from family members.Genomic DNA was extracted from total blood samples using a standard phenol-chloroform extraction.The genetic linkage analysis was performed using microsatellite markers.Two-point linkage analysis was performed using the LINKAGE program.Five members underwent detailed neurological examinations and 4 members underwent electrophysiological analysis,cervical and thoracic MRI and serum enzymes.Results Linkage analysis mapped the AD-HSP locus to chromosome 2p12(SPG31)in this family.Positive LOD scores were obtained for SPG31 markers on chromosome 2 with a maximum multipoint LOD score of Z=1.8.Analysis of the REEP1 gene revealed a heterozygous G-to-A mutation at nucleotide position c417+1 donor site in exon 5.resulting in splice-site mutation.The symptoms of the patients manifested as stiffness,instability or weakness of the legs.MRI of the thoracic revealed atrophies of the spinal cord in the proband's son.Conclusions SPC31 patients have the clinical features of the typical HSP characteristics.REEP1 gene is the pathogenic gene.with REEP1 c417+1G＞A heterozygous mutation.     

Neurotrophin receptors,gamma-secretase inhibitors,and neurodegeneration of basal forebrain cholinergic neurons

The amyloid hypothesis of Alzhemer’s disease(AD)postulates that the generation of amyloid-beta(Aβ)peptide from the amyloid precursor protein(APP)by the action of theγ-secretase complex is one of the principal causes of AD.This idea is supported by the identification of several hereditary mutations in the APP gene or in the PSEN1 and PSEN2 genes that encode Presenilin-1 and Presenilin-2.     

Proteolipid protein 1 gene sequencing of hereditary spastic paraplegia

PCR amplification and sequencing of whole blood DNA from an individual with hereditary spastic paraplegia, as well as family members, revealed a fragment of proteolipid protein 1 (PLP1) gene exon 1, which excluded the possibility of isomer 1 expression for this family. The fragment sequence of exon 3 and exon 5 was consistent with the proteolipid protein 1 sequence at NCBI. In the proband samples, a PLP1 point mutation in exon 4 was detected at the basic group of position 844, T→C, phenylalanine→leucine. In proband samples from a male cousin, the basic group at position 844 was C, but gene sequencing signals revealed mixed signals of T and C, indicating possible mutation at this locus. Results demonstrated that changes in PLP1 exon 4 amino acids were associated with onset of hereditary spastic paraplegia.     

核黄素反应性脂质沉积性肌病20个家系的电子转移黄素蛋白脱氢酶基因存在热点突变

目的 报道20个核黄素反应性脂质沉积性肌病(RR-LSM)患者的电子转移黄素蛋白脱氧酶(ETFDH)基因检查结果.方法 对2003年1月至2010年5月我院神经科收治的24例RRLSM患者(来自20个我国大陆北方地区RR-LSM家系,其中16个家系各有1例患者,其余4个家系各有2例发病者)的临床特点进行分析.对24例患者、11名无症状家系成员以及100名健康人行ETFDH基因检查.结果 24例患者发病年龄为(27.9±9.9)岁,主要症状为四肢无力(21例,87.5%)、咀嚼困难(15例,62.5%)、颈肌无力(14例,58.3%)和肌痛(14例,58.3%)等.18例患者的血代谢筛查均提示脂酰肉碱升高,17例患者中有15例存在戊二酸尿症.我们发现19个家系存在17种ETFDH基因点突变,包括13种错义突变、2种剪切突变和2种无义突变.其中患者的c.998A>G、c.1450T>C、c.1703T>C、c.11717C>T、c.821G>A、c.643G>A、c.25IC>T、c.1763A>T、c.IVS7+2T>C、c.IVS6+1G>A没有出现在100名健康人中.有9个家系存在c.770A>G(P.Y257C)突变;5个家系存在c.1227A>C(P.L409F)突变.结论 诸多ETFDH基因新突变提示国人RR-LSM可能存在特殊的基因突变谱,其中P.Y257C与P.L409F突变可能为我国大陆北方地区的热点突变.

Abstract：

Objective To report the spectrum of electron transfer flavoprotein dehydrogenase (ETFDH)gene mutations in 20 Chinese RR-LsM families.Methods Twenty-four RR-LSM patients in the First Hospital of Peking University from January 2003 to May 2010 were collected and the clinical characteristics were analyzed.These patients came from 20 families in North Mainland China.Sixteen families had 1 patient each.and the other 4 families had 2 patients.ETFDH gene analysis was performed in all patients,11 family members and 100 healthy controls.Results The mean onset age was(27.9±9.9)years.The main symptoms were limb weakness(21,87.5%),dysmasesia(15,62.5%),neck weakness (14,58.3%)and myalgia(14,58.3%).Eighteen patients had high level of acyleamitine.Fifteen of 17patients had glutaric aciduria.Seventeen ETFDH mutations,including 13 missense mutations,2 splice mutations,and 2 nonsense mutations,were identified in 19 families:c.998A>G,c.1450T>C,c.1703T>C,c.1717C>T,c.821G>A,c.643G>A,c.251C>T,c.1763A>T,c.IVS7+2T>C and c.IVS6+1G>A were Hovel mutations which were not found in 100 healthy controls.Nine families had the mutation of c.770A>G(P.Y257C)and 5 families had the mutation of c.1227A>C(P.L409F).Conclusions The numerous novel mutations in ETFDH gene indicate that Chinese RR-LSM might have special mutation pattern.c.770A>G(P.Y257C)and c.1227A>C(p.L409F)may be hot spot mutations in North Mainland China.     

老年全身麻醉患者认知功能与载脂蛋白Eε4基因单核苷酸多态性的相关性：1000例随机分组对照

BACKGROUND： Cognitive dysfunction occurs in elderly patients following general anesthesia, and this might be associated with genetics. Studies have shown that the ε4 allele gene is closely associated with senile dementia. OBJECTIVE： To compare and analyze the correlations between cognitive dysfunction and single nucleotide polymorphism of apolipoprotein E （ApoE） following inhalation or intravenous anesthesia. DESIGN, TIME AND SETTING： A randomized, controlled study was performed. The patients were recruited from the Department of Anesthesia, Second Affiliated Hospital, Medical College, Xi＇an Jiaotong University, China between May 2005 and December 2008. Genetic analyses were conducted at the Departments of Neuroanatomy and Forensic Medicine, Medical Corlege, Xi＇an Jiaotong University, China. PARTICIPANTS： A total of t 000 patients of ASA I-II grade, without genetic connection, were enrolled in this study, comprising 520 males and 480 females, aged （70.1± 4.6） years and weighing （57.3 ± 7.5） kg. No patients suffered from cognitive dysfunction. METHODS： The patients were equally and randomly divided into intravenous anesthesia and gas anesthesia groups. Total intravenous anesthesia and inhaled anesthesia were used. Genomic DNA from whole blood was extracted. The ApoE gene was amplified by PCR. Restriction fragment length polymorphism of ApoE gene was analyzed. Cognitive function was evaluated by Mini-Mental State Examination （MMSE）. Patients scoring 〈 25 points were diagnosed with cognitive dysfunction. MAIN OUTCOME MEASURES： Correlation of ApoE gene frequency and ApoE ε 4 allele to MMSE scores was measured. RESULTS： MMSE scores in patients from the gas anesthesia group significantly decreased 3 days after surgery, compared with the intravenous anesthesia group. The proportion of patients that scored 〈 25 points was significantly greater in the gas anesthesia group compared with the intravenous anesthesia group 3 days after surgery. Reduced MMSE scores closely correlated with expression of the ApoE ε 4 allele in the gas anesthesia group （odds ratio = 2.83; 95% confidence interval was 1.25-6.39, P 〈 0.05）. However, decreased MMSE scores did not closely correlated with expression of the ApoE ε 4 allele in the intravenous anesthesia group （odds ratio = 0.96; 95% confidence interval was 0.37-2.39, P 〉 0.05）. CONCLUSION： Results demonstrated a correlation between cognitive dysfunction and ApoE single nucleotide polymorphism in elderly patients after gas anesthesia. However, no relationship between cognitive dysfunction and ApoE single nucleotide polymorphism was determined in elderly patients following intravenous anesthesia. Therefore, elderly patients, especially those expressing the ApoE ε4 gene, should be cautiously exposed to gas anesthesia.     

PARK1 gene mutation of autosomal dominant Parkinson’s disease family

Studies have shown that PARK1 gene is associated with the autosomal dominant inheritance of Parkinson’s disease. PARK1 gene contains two mutation sites, namely Ala30Pro and Ala53Thr, which are located on exons 3 and 4, respectively. However, the genetic loci of the pathogenic genes remain unclear. In this study, blood samples were collected from 11 members of a family with high prevalence of Parkinson’s disease, including four affected cases, five suspected cases, and two non-affected cases. Point mutation screening of common mutation sites on PARK1 gene exon 4 was conducted using PCR, to determine the genetic loci of the causative gene for Parkinson’s disease. Gene identification and sequencing results showed that a T base deletion mutation was observed in the PARK1 gene exon 4 of all 11 collected samples. It was confirmed that the PARK1 gene exon 4 gene mutation is an important pathogenic mutation for Parkinson’s disease.     

A crate of Pandora:do amyloids from bacteria promote Alzheimer's disease?

正Incidence for microbes as drivers of Alzheimer’s disease (AD) pathology:AD is the predominant neurodegenerative disease within the elderly. Over 50 million patients suffer from dementia currently world-wide and an estimated tripling of numbers within the next 30 years is expected. Only one to maximally five percent of all cases of AD are based on mutations in the amyloid precursor protein (APP) gene or within the presenilin genes (PS1/PS2) and therefore are called familial (FAD).     

A novel mutation in the PSEN2 gene (T430M) associated with variable expression in a family with early-onset Alzheimer disease

BACKGROUND: Autosomal dominant early-onset Alzheimer disease is a heterogeneous condition that has been associated with mutations in 3 different genes: the amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) genes. Most cases are due to mutations in the PSEN1 gene, whereas mutations in the APP and PSEN2 genes are rare. OBJECTIVE: To describe a novel mutation in the PSEN2 gene associated with early-onset autosomal dominant Alzheimer disease. PATIENTS AND METHODS: The proband was a 49-year-old individual who displayed progressive dementia beginning at age 45 years. One of the parents and one of the grandparents had developed dementia at ages 64 years and 60 years, respectively, and 1 sibling had mild cognitive impairment. Some family members also had Tourette syndrome. Mutation analysis of the APP, PSEN1, PSEN2, and tau (TAU) genes was performed. Apolipoprotein E (APOE) was also genotyped. RESULTS: We found a missense mutation at codon 430 of the PSEN2 gene that predicts a threonine-to-methionine substitution. This mutation was detected in the affected individuals and in 1 cognitively healthy sibling. The mutation was absent in 260 control chromosomes. The normal amino acid was conserved in the human and mouse PSEN1 and mouse PSEN2 homologues. No influence of the APOE genotype was observed. CONCLUSIONS: We have found a novel mutation in the PSEN2 gene in a family with early-onset Alzheimer disease. The variation in the age at onset confirms that PSEN2 mutations are associated with variable clinical expression.     

Familial Alzheimer's disease with presenilin 2 N141I mutation. A case report

Alzheimer's disease (AD) is the most common form of dementia. Approximately 0.5 per cent of all AD is caused by single major gene mutations and autosomal dominant inheritance. These familial types with early-onset (EOFAD) usually display dementia before the age of 60. Such mutations have been found in the gene encoding amyloid precursor protein (APP), and in the genes encoding presenilin 1 (PSEN1) or presenilin 2 (PSEN2). We herein report the case of a German patient with a EOFAD and a missense mutation at codon 141 (N141I) of the PSEN2 gene. The patient came to our psychiatric clinic for the first time when she was 49 years old. During the following 3 years, her Mini-Mental-State-Examination (MMSE) score dropped from 14 to 0 points. Positron emission tomography with [18F] Fluorodeoxyglucose (18F-FDG PET) demonstrated glucose reduction left parietal and in the pre-cuneus region. Follow-up 18F-FDG PET studies showed progressive hypometabolism of both temporoparietal lobes and left frontal lobe.     

Mutations in presenilin 1, presenilin 2 and amyloid precursor protein genes in patients with early-onset Alzheimer's disease in Poland

Mutations in three causative genes have been identified in patients with an autosomal-dominant form of early-onset Alzheimer's disease (EOAD). To determine the spectrum of mutations in a group consisting of 40 Polish patients with clinically diagnosed familial EOAD and 1 patient with mild cognitive impairment (MCI) and family history of AD, we performed a screening for mutations in the presenilin 1 (PSEN1), presenilin 2 (PSEN2) and amyloid precursor protein (APP) genes. Four previously recognized pathogenic mutations in PSEN1 gene (H163R, M139V) and APP gene (T714A, V715A), and three novel putative mutations in PSEN1 gene (P117R and I213F) and PSEN2 gene (Q228L) were identified. The 34 patients with no mutations detected were older than the patients with mutations. A frequency of APOE4 allele was higher in this group. Frequency of mutations is relatively low (17%), possibly due to used operational definition of a patient with familial EOAD (a patient having at least one relative with early-onset dementia). It could be concluded that screening for mutations in the three genes could be included in a diagnostic program directed at patients with a positive family history or age of onset before 55 years.     

A presenilin 1 mutation (Arg278Ser) associated with early onset Alzheimer's disease and spastic paraparesis

Early onset familial Alzheimer’s disease (EOFAD) has been associated with mutations in three genes, of which presenilin 1 (PSEN1) mutations are the most frequent. Several families with an association of progressive dementia and spastic paraplegia caused by PSEN1 mutations have been described. Here we described a novel PSEN1 mutation that was associated with dementia and spastic paraplegia in a family with 5 affected individuals in three generations. The proband was a 44-year-old woman who presented with 5 years history of progressive difficulties in walking, cognition and visuospatial impairment. Her maternal grandmother, mother and two maternal aunts also had similar neurological presentation. Molecular genetic analysis showed a missense mutation predicted to substitute an arginine residue for a serine residue at position 278 in the PSEN1 polypeptide (Arg278Ser). The novel PSEN1 mutation identified in this patient adds to the diverse list of existing mutations causing EOFAD associated with spastic paraparesis.     

Identification of a Novel Mutation in the Presenilin 1 Gene in a Chinese Alzheimer’s Disease Family

This study has identified a gene mutation in a Chinese family with Alzheimer’s disease (AD). Family members were screened by a set of medical examinations and neuropsychological tests. Their DNA was extracted from blood cells and sequenced for gene mutation in the amyloid precursor protein (APP), the presenilin 1 (PS1) and the presenilin 2 (PS2) genes. Genetic analysis showed that the AD patients in the family harbored a T to G missense mutation at the position 314 in exon 4 of the PS1 gene, resulting in a change of F105C in amino acid sequence. Clinical manifestation of these patients included memory loss, counting difficulty, personality change, disorientation, dyscalculia, agnosia, aphasia, and apraxia, which was similar to that of the familial AD (FAD) patients harboring other PS1 mutations. We intend to add a novel mutation F105C of the PS1 gene to the pool of FAD mutations. With the current available genetic data, mutations of the PS1 gene account for the majority of gene mutations in Chinese FAD.     

Early-onset familial Alzheimer's disease (EOFAD)

Early-onset familial Alzheimer's disease (EOFAD) is a condition characterized by early onset dementia (age at onset < 65 years) and a positive family history for dementia. To date, 230 mutations in presenilin (PS1, PS2) and amyloid precursor protein (APP) genes have been identified in EOFAD. The mutations within these three genes (PS1/PS2/APP) affect a common pathogenic pathway in APP synthesis and proteolysis, which lead to excessive production of amyloid β. Compared with sporadic Alzheimer's disease (AD), EOFAD has some distinctive features including early age at onset, positive familial history, a variety of non-cognitive neurological symptoms and signs, and a more aggressive course. There is marked phenotypic heterogeneity among different mutations of EOFAD. Studies in presymptomatic mutation carriers reveal biomarkers abnormalities. EOFAD diagnosis is based on clinical and family history, neurological symptoms and examination, biomarker features, as well as genotyping in some cases. New therapeutic agents targeting amyloid formation may benefit EOFAD individuals.     

Identification of new presenilin gene mutations in early-onset familial Alzheimer disease

BACKGROUND: Mutations in the presenilin 1 (PS1) and presenilin 2 (PS2) genes, and more rarely in beta-amyloid precursor protein (betaAPP), underlie the pathogenesis of most cases of familial Alzheimer disease (FAD). OBJECTIVE: To screen the entire coding region of the PS1 and PS2 genes and exons 16 and 17 of the betaAPP to find pathogenetic mutations in FAD.Patients Patients with FAD were consecutively enrolled from among the outpatients from the neurology departments at the Universities of Florence and Parma and the Santa Maria Nuova Hospital in Reggio Emilia, Italy. DESIGN AND METHODS: Polymerase chain reaction-single-strand conformation polymorphism and DNA se-quencing were used to investigate the affected members of families with FAD. RESULTS: We identified a family carrying a novel Ser130Leu mutation in the PS2 gene. Moreover, we found 2 novel PS1 mutations: Cys92Ser in exon 4 in 2 unrelated families and Leu174Met in exon 6 in the PS1 gene. We also found a fourth Italian family with the betaAPP Val717Ile mutation. CONCLUSIONS: One novel PS2 mutation associated with highly penetrant but variable age at onset (35-85 years) and 2 novel PS1 missense mutations associated with early-onset Alzheimer disease at age 49 to 54 years have been identified in Italian families. Screening for new mutations in presenilin and betaAPP genes was beneficial in characterizing gene function in FAD.     

Clinical phenotype of G206D mutation in the presenilin 1 gene in pathologically confirmed familial Alzheimer's disease

Familial Alzheimer's disease (FAD) is genetically heterogeneous, autosomal dominant, with nearly 100% penetrance. In FAD, most common causative genetic mutations are presenilin 1 (PSEN1), presenilin 2 and amyloid-β protein precursor. We demonstrate a family presenting as early-onset AD with a rapid deterioration course and seizure developed after 1.5 years of symptoms. A histopathological examination of the frontal cortex showed amyloid deposition and abundant phosphorylated tau deposition. In both cases, a single nucleotide mutation from guanine to adenine at exon 7 was found in PSEN1 (c.617G>A, codon change from GGT to GAT). Though G206D mutation in PSEN1 gene was found in FAD, no clinical phenotype or pathological finding was documented. This is the first report of PSEN1 mutation (Gly206Asp) with features of seizure and a rapid progressive cognitive decline in a pathologically confirmed case of FAD.     

Time course of glucose metabolism in relation to cognitive performance and postmortem neuropathology in Met146Val PSEN1 mutation carriers

Studies in carriers of mutations that cause early-onset familial Alzheimer’s disease (eoFAD) are of significant interest.We showed previously that regional glucose hypometabolism could be detected many years before disease onset in presenilin 1(PSEN1) mutation carriers. Here we studied four members of a family with a Met146Val PSEN1 mutation, two symptomatic carriers and two non-carriers, longitudinally with 18F-FDG PET over a period of about two and four years, respectively. The two mutation carriers showed global cortical glucose hypometabolism over time with the most distinct decline occurring in the posterior cingulate, the parietal and parietotemporal cortex, which was also observed when compared with a group of 23 healthy controls and a group of 27 sporadic Alzheimer’s disease (sAD) patients. This decline correlated with cognitive deterioration overtime as measured by neuropsychological tests. Postmortem examination of brain tissue revealed substantially elevated levels of AD type neuropathology in terms of neuritic plaques and neurofibrillary tangles in the two mutation carriers compared with a reference group of 249 sAD patients. In the mutation carriers, the amount of neuritic plaques but not neurofibrillary tangles correlated hereby significantly with regional glucose metabolism as measured by 18F-FDG on the last scanning occasions, which were performed four and approximately five years before death, respectively. We here show that FDG PET can depict in vivo the aggressive disease progression in eoFAD mutation carriers in relationship to neuropathology.     

Two novel presenilin 1 gene mutations connected with frontotemporal dementia-like clinical phenotype: genetic and bioinformatic assessment

Mutations in the amyloid precursor protein (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2) genes are associated with early-onset familial Alzheimer's disease (EOAD). There are several reports describing mutations in PSEN1 in cases with frontotemporal dementia (FTD). We identified two novel mutations in the PSEN1 gene: L226F and L424H. The first mutation was detected in a patient with a clinical diagnosis of FTD and a post-mortem diagnosis of AD. The second mutation is connected with a clinical phenotype of variant AD with strong FTD signs. In silico modeling revealed that the mutations, as well as mutations used for comparison (F177L and L424R), change the local structure, stability and/or properties of the transmembrane regions of the presenilin 1 protein (PS1). In contrast, a silent non-synonymous substitution F175S is eclipsed by external residues and has no influence on PS1 interfacial surface. We suggest that in silico analysis of PS1 substitutions can be used to characterize novel PSEN1 mutations, to discriminate between silent polymorphisms and a potential disease-causing mutation. We also propose that PSEN1 mutations should be considered in FTD patients with no MAPT mutations.