Rapid detection of IDH mutations in gliomas by intraoperative mass spectrometry.

The development and performance of two mass spectrometry (MS) workflows for the intraoperative diagnosis of isocitrate dehydrogenase (IDH) mutations in glioma is implemented by independent teams at Mayo Clinic, Jacksonville, and Huashan Hospital, Shanghai. The infiltrative nature of gliomas makes rapid diagnosis necessary to guide the extent of surgical resection of central nervous system (CNS) tumors. The combination of tissue biopsy and MS analysis used here satisfies this requirement. The key feature of both described methods is the use of tandem MS to measure the oncometabolite 2-hydroxyglutarate (2HG) relative to endogenous glutamate (Glu) to characterize the presence of mutant tumor. The experiments i) provide IDH mutation status for individual patients and ii) demonstrate a strong correlation of 2HG signals with tumor infiltration. The measured ratio of 2HG to Glu correlates with IDH-mutant (IDH-mut) glioma (P < 0.0001) in the tumor core data of both teams. Despite using different ionization methods and different mass spectrometers, comparable performance in determining IDH mutations from core tumor biopsies was achieved with sensitivities, specificities, and accuracies all at 100%. None of the 31 patients at Mayo Clinic or the 74 patients at Huashan Hospital were misclassified when analyzing tumor core biopsies. Robustness of the methodology was evaluated by postoperative re-examination of samples. Both teams noted the presence of high concentrations of 2HG at surgical margins, supporting future use of intraoperative MS to monitor for clean surgical margins. The power of MS diagnostics is shown in resolving contradictory clinical features, e.g., in distinguishing gliosis from IDH-mut glioma.

Active N6-Methyladenine Demethylation by DMAD Regulates Gene Expression by Coordinating with Polycomb Protein in Neurons.

A ten-eleven translocation (TET) ortholog exists as a DNA N6-methyladenine (6mA) demethylase (DMAD) in Drosophila. However, the molecular roles of 6mA and DMAD remain unexplored. Through genome-wide 6mA and transcriptome profiling in Drosophila brains and neuronal cells, we found that 6mA may epigenetically regulate a group of genes involved in neurodevelopment and neuronal functions. Mechanistically, DMAD interacts with the Trithorax-related complex protein Wds to maintain active transcription by dynamically demethylating intragenic 6mA. Accumulation of 6mA by depleting DMAD coordinates with Polycomb proteins and contributes to transcriptional repression of these genes. Our findings suggest that active 6mA demethylation by DMAD plays essential roles in fly CNS by orchestrating through added epigenetic mechanisms.

Specific serum autoantibodies predict the development and progression of Alzheimer's disease with high accuracy.

Autoimmunity plays a key role in the pathogenesis of Alzheimer's disease (AD). However, whether autoantibodies in peripheral blood can be used as biomarkers for AD has been elusive. Serum samples were obtained from 1,686 participants, including 767 with AD, 146 with mild cognitive impairment (MCI), 255 with other neurodegenerative diseases, and 518 healthy controls. Specific autoantibodies were measured using a custom-made immunoassay. Multivariate support vector machine models were employed to investigate the correlation between serum autoantibody levels and disease states. As a result, seven candidate AD-specific autoantibodies were identified, including MAPT, DNAJC8, KDM4D, SERF1A, CDKN1A, AGER, and ASXL1. A classification model with high accuracy (area under the curve (AUC) = 0.94) was established. Importantly, these autoantibodies could distinguish AD from other neurodegenerative diseases and out-performed amyloid and tau protein concentrations in cerebrospinal fluid in predicting cognitive decline (P < 0.001). This study indicated that AD onset and progression are possibly accompanied by an unappreciated serum autoantibody response. Therefore, future studies could optimize its application as a convenient biomarker for the early detection of AD.

The risk of Alzheimer's disease and cognitive impairment characteristics in eight mental disorders: A UK Biobank observational study and Mendelian randomization analysis.

INTRODUCTION: The cognitive impairment patterns and the association with Alzheimer's disease (AD) in mental disorders remain poorly understood. METHODS: We analyzed data from 486,297 UK Biobank participants, categorizing them by mental disorder history to identify the risk of AD and the cognitive impairment characteristics. Causation was further assessed using Mendelian randomization (MR). RESULTS: AD risk was higher in individuals with bipolar disorder (BD; hazard ratio [HR] = 2.37, P < 0.01) and major depressive disorder (MDD; HR = 1.63, P < 0.001). MR confirmed a causal link between BD and AD (ORIVW = 1.098), as well as obsessive-compulsive disorder (OCD) and AD (ORIVW = 1.050). Cognitive impairments varied, with BD and schizophrenia showing widespread deficits, and OCD affecting complex task performance. DISCUSSION: Observational study and MR provide consistent evidence that mental disorders are independent risk factors for AD. Mental disorders exhibit distinct cognitive impairment prior to dementia, indicating the potential different mechanisms in AD pathogenesis. Early detection of these impairments in mental disorders is crucial for AD prevention. HIGHLIGHTS: This is the most comprehensive study that investigates the risk and causal relationships between a history of mental disorders and the development of Alzheimer's disease (AD), alongside exploring the cognitive impairment characteristics associated with different mental disorders. Individuals with bipolar disorder (BD) exhibited the highest risk of developing AD (hazard ratio [HR] = 2.37, P < 0.01), followed by those with major depressive disorder (MDD; HR = 1.63, P < 0.001). Individuals with schizophrenia (SCZ) showed a borderline higher risk of AD (HR = 2.36, P = 0.056). Two-sample Mendelian randomization (MR) confirmed a causal association between BD and AD (ORIVW = 1.098, P < 0.05), as well as AD family history (proxy-AD, ORIVW = 1.098, P < 0.001), and kept significant after false discovery rate correction. MR also identified a nominal significant causal relationship between the obsessive-compulsive disorder (OCD) spectrum and AD (ORIVW = 1.050, P < 0.05). Individuals with SCZ, BD, and MDD exhibited impairments in multiple cognitive domains with distinct patterns, whereas those with OCD showed only slight declines in complex tasks.

A detection model of cognitive impairment via the integrated gait and eye movement analysis from a large Chinese community cohort.

INTRODUCTION: Whether the integration of eye-tracking, gait, and corresponding dual-task analysis can distinguish cognitive impairment (CI) patients from controls remains unclear. METHODS: One thousand four hundred eighty-one participants, including 724 CI and 757 controls, were enrolled in this study. Eye movement and gait, combined with dual-task patterns, were measured. The LightGBM machine learning models were constructed. RESULTS: A total of 105 gait and eye-tracking features were extracted. Forty-six parameters, including 32 gait and 14 eye-tracking features, showed significant differences between two groups (P < 0.05). Of these, the Gait_3Back-TurnTime and Dual-task cost-TurnTime patterns were significantly correlated with plasma phosphorylated tau 181 (p-tau181) level. A model based on dual-task gait, dual-task smooth pursuit, prosaccade, and anti-saccade achieved the best area under the receiver operating characteristics curve (AUC) of 0.987 for CI detection, while combined with p-tau181, the model discriminated mild cognitive impairment from controls with an AUC of 0.824. DISCUSSION: Combining dual-task gait and dual-task eye-tracking analysis is feasible for the detection of CI. HIGHLIGHTS: This is the first study to report the efficiency of integrated parameters of dual-task gait and eye-tracking for cognitive impairment (CI) detection in a large cohort. We identified 46 gait and eye-tracking features associated with CI, and two were correlated to plasma phosphorylated tau 181. We constructed the model based on dual-task gait, smooth pursuit, prosaccade, and anti-saccade, achieving the best area under the curve of 0.987 for CI detection.

Downregulation of TOP2 modulates neurodegeneration caused by GGGGCC expanded repeats.

GGGGCC repeats in a non-coding region of the C9orf72 gene have been identified as a major genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. We previously showed that the GGGGCC expanded repeats alone were sufficient to cause neurodegeneration in Drosophila. Recent evidence indicates that GGGGCC expanded repeats can modify various gene transcriptomes. To determine the role of these genes in GGGGCC-mediated neurotoxicity, we screened an established Drosophila model expressing GGGGCC expanded repeats in this study. Our results showed that knockdown of the DNA topoisomerase II (Top2) gene can specifically modulate GGGGCC-associated neurodegeneration of the eye. Furthermore, chemical inhibition of Top2 or siRNA-induced Top2 downregulation could alleviate the GGGGCC-mediated neurotoxicity in Drosophila assessed by eye neurodegeneration and locomotion impairment. By contrast, upregulated Top2 levels were detected in Drosophila strains, and moreover, TOP2A level was also upregulated in Neuro-2a cells expressing GGGGCC expanded repeats, as well as in the brains of Sod1G93A model mice. This indicated that elevated levels of TOP2A may be involved in a pathway common to the pathophysiology of distinct ALS forms. Moreover, through RNA-sequencing, a total of 67 genes, involved in the pathways of intracellular signaling cascades, peripheral nervous system development, and others, were identified as potential targets of TOP2A to modulate GGGGCC-mediated neurodegeneration.

GSN gene frameshift mutations in Alzheimer's disease.

BACKGROUND: The pathogenic missense mutations of the gelsolin (GSN) gene lead to familial amyloidosis of the Finnish type (FAF); however, our previous study identified GSN frameshift mutations existed in patients with Alzheimer's disease (AD). The GSN genotype-phenotype heterogeneity and the role of GSN frameshift mutations in patients with AD are unclear. METHOD: In total, 1192 patients with AD and 1403 controls were screened through whole genome sequencing, and 884 patients with AD were enrolled for validation. Effects of GSN mutations were evaluated in vitro. GSN, Aß42, Aß40 and Aß42/40 were detected in both plasma and cerebrospinal fluid (CSF). RESULTS: Six patients with AD with GSN P3fs and K346fs mutations (0.50%, 6/1192) were identified, who were diagnosed with AD but not FAF. In addition, 13 patients with AD with GSN frameshift mutations were found in the validation cohort (1.47%, 13/884). Further in vitro experiments showed that both K346fs and P3fs mutations led to the GSN loss of function in inhibiting Aß-induced toxicity. Moreover, a higher level of plasma (p=0.001) and CSF (p=0.005) GSN was observed in AD cases than controls, and a positive correlation was found between the CSF GSN and CSF Aß42 (r=0.289, p=0.009). Besides, the GSN level was initially increasing and then decreasing with the disease course and cognitive decline. CONCLUSIONS: GSN frameshift mutations may be associated with AD. An increase in plasma GSN is probably a compensatory reaction in AD, which is a potential biomarker for early AD.

Diagnostic value of nerve conduction study in NOTCH2NLC-related neuronal intranuclear inclusion disease.

BACKGROUND AND AIMS: Neuronal intranuclear inclusion disease (NIID) is a rare progressive neurodegenerative disorder mainly caused by abnormally expanded GGC repeats within the NOTCH2NLC gene. Most patients with NIID show polyneuropathy. Here, we aim to investigate diagnostic electrophysiological markers of NIID. METHODS: In this retrospective dual-center study, we reviewed 96 patients with NOTCH2NLC-related NIID, 94 patients with genetically confirmed Charcot-Marie-Tooth (CMT) disease, and 62 control participants without history of peripheral neuropathy, who underwent nerve conduction studies between 2018 and 2022. RESULTS: Peripheral nerve symptoms were presented by 53.1% of patients with NIID, whereas 97.9% of them showed peripheral neuropathy according to electrophysiological examinations. Patients with NIID were characterized by slight demyelinating sensorimotor polyneuropathy; some patients also showed mild axonal lesions. Motor nerve conduction velocity (MCV) of the median nerve usually exceeded 35 m/s, and were found to be negatively correlated with the GGC repeat sizes. Regarding the electrophysiological differences between muscle weakness type (n = 27) and non-muscle weakness type (n = 69) of NIID, nerve conduction abnormalities were more severe in the muscle weakness type involving both demyelination and axonal impairment. Notably, specific DWI subcortical lace sign was presented in only 33.3% of muscle weakness type, thus it was difficult to differentiate them from CMT. Combining age of onset, distal motor latency, and compound muscle action potential of the median nerve showed the optimal diagnostic performance to distinguish NIID from major CMT (AUC = 0.989, sensitivity = 92.6%, specificity = 97.4%). INTERPRETATION: Peripheral polyneuropathy is common in NIID. Our study suggest that nerve conduction study is useful to discriminate NIID.

ALS-plus related clinical and genetic study from China.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder. An increasing number of researchers have found extra motor features in ALS, which are also called ALS-plus syndromes. Besides, a great majority of ALS patients also have cognitive impairment. However, clinical surveys of the frequency and genetic background of ALS-plus syndromes are rare, especially in China. METHODS: We investigated a large cohort of 1015 patients with ALS, classifying them into six groups according to different extramotor symptoms and documenting their clinical manifestations. Meanwhile, based on their cognitive function, we divided these patients into two groups and compared demographic characteristics. Genetic screening for rare damage variants (RDVs) was also performed on 847 patients. RESULTS: As a result, 16.75% of patients were identified with ALS-plus syndrome, and 49.5% of patients suffered cognitive impairment. ALS-plus group had lower ALSFRS-R scores, longer diagnostic delay time, and longer survival times, compared to ALS pure group. RDVs occurred less frequently in ALS-plus patients than in ALS-pure patients (P = 0.042) but showed no difference between ALS-cognitive impairment patients and ALS-cognitive normal patients. Besides, ALS-cognitive impairment group tends to harbour more ALS-plus symptoms than ALS-cognitive normal group (P = 0.001). CONCLUSION: In summary, ALS-plus patients in China are not rare and show multiple differences from ALS-pure patients in clinical and genetic features. Besides, ALS-cognitive impairment group tends to harbour more ALS-plus syndrome than ALS-cognitive normal group. Our observations correspond with the theory that ALS involves several diseases with different mechanisms and provide clinical validation.

A detection model for cognitive dysfunction based on volatile organic compounds from a large Chinese community cohort.

INTRODUCTION: We explored whether volatile organic compound (VOC) detection can serve as a screening tool to distinguish cognitive dysfunction (CD) from cognitively normal (CN) individuals. METHODS: The cognitive function of 1467 participants was assessed and their VOCs were detected. Six machine learning algorithms were conducted and the performance was determined. The plasma neurofilament light chain (NfL) was measured. RESULTS: Distinguished VOC patterns existed between CD and CN groups. The CD detection model showed good accuracy with an area under the receiver-operating characteristic curve (AUC) of 0.876. In addition, we found that 10 VOC ions showed significant differences between CD and CN individuals (p < 0.05); three VOCs were significantly related to plasma NfL (p < 0.005). Moreover, a combination of VOCs with NfL showed the best discriminating power (AUC = 0.877). DISCUSSION: Detection of VOCs from exhaled breath samples has the potential to provide a novel solution for the dilemma of CD screening.

Genetics of progressive supranuclear palsy in a Chinese population.

BACKGROUND: Genetics plays an important role in progressive supranuclear palsy (PSP) and remains poorly understood. A detailed literature search identified 19 PSP-associated genes: MAPT, LRRK2, LRP10, DCTN1, GRN, NPC1, PARK, TARDBP, TBK1, BSN, GBA, STX6, EIF2AK3, MOBP, DUSP10, SLCO1A2, RUNX2, CXCR4, and APOE. To date, genetic studies on PSP have focused on Caucasian population. The gaps in PSP genetic study on East Asian populations need to be filled. METHODS: Exon and flanking regions of the PSP-associated genes were sequenced in 104 patients with PSP and 488 healthy controls. Common variant-based association analysis and gene-based association tests of rare variants were performed using PLINK 1.9 and the sequence kernel association test-optimal, respectively. Additionally, the association of APOE and MAPT genotypes with PSP was evaluated. The above association analyses were repeated among probable PSP patients. Finally, PLINK 1.9 was used to test variants associated with the onset age of PSP. RESULTS: A rare non-pathogenic variant of MAPT (c.425C > T,p.A142V) was detected in a PSP patient. No common variants were significantly associated with PSP. In both the rare-variant and the rare-damaging-variant groups, the combined effect for GBA reached statistical significance (p = 1.43 × 10-3, p = 4.98 × 10-4). The result between APOE, MAPT genotypes and PSP risk were inconsistent across all PSP group and probably PSP group. CONCLUSIONS: The pathogenic variant in MAPT were uncommon in PSP patients. Moreover, GBA gene was likely to increase the risk of PSP, and GBA-associated diseases were beyond α-synucleinopathies. The association between APOE, MAPT and PSP is still unclear among the non-Caucasian population.

Expansion of Human-Specific GGC Repeat in Neuronal Intranuclear Inclusion Disease-Related Disorders.

Neuronal intranuclear inclusion disease (NIID) is a slowly progressing neurodegenerative disease characterized by eosinophilic intranuclear inclusions in the nervous system and multiple visceral organs. The clinical manifestation of NIID varies widely, and both familial and sporadic cases have been reported. Here we have performed genetic linkage analysis and mapped the disease locus to 1p13.3-q23.1; however, whole-exome sequencing revealed no potential disease-causing mutations. We then performed long-read genome sequencing and identified a large GGC repeat expansion within human-specific NOTCH2NLC. Expanded GGC repeats as the cause of NIID was further confirmed in an additional three NIID-affected families as well as five sporadic NIID-affected case subjects. Moreover, given the clinical heterogeneity of NIID, we examined the size of the GGC repeat among 456 families with a variety of neurological conditions with the known pathogenic genes excluded. Surprisingly, GGC repeat expansion was observed in two Alzheimer disease (AD)-affected families and three parkinsonism-affected families, implicating that the GGC repeat expansions in NOTCH2NLC could also contribute to the pathogenesis of both AD and PD. Therefore, we suggest defining a term NIID-related disorders (NIIDRD), which will include NIID and other related neurodegenerative diseases caused by the expanded GGC repeat within human-specific NOTCH2NLC.

Development of a Miniature Mass Spectrometry System for Point-of-Care Analysis of Lipid Isomers Based on Ozone-Induced Dissociation.

Disorder of lipid homeostasis is closely associated with a variety of diseases. Although mass spectrometry (MS) approaches have been well developed for the characterization of lipids, it still lacks an integrated and compact MS system that is capable of rapid and detailed lipid structural characterization and can be conveniently transferred into different laboratories. In this work, we describe a novel miniature MS system with the capability of both ozone-induced dissociation (OzID) and collision-induced dissociation (CID) for the assignment of sites of unsaturation and sn-positions in glycerolipids. A miniature ozone generator was developed, which can be operated at a relatively high pressure. By maintaining high-concentration ozone inside the linear ion trap, OzID efficiency was significantly improved for the identification of C═C locations in unsaturated lipids, with reaction times as short as 10 ms. Finally, the miniature OzID MS system was applied to the analysis of C═C locations and sn-positions of lipids from biological samples. Direct sampling and fast detection of changes in phospholipid isomers were demonstrated for the rapid discrimination of breast cancer tissue samples, showing the potential of the miniature OzID MS system for point-of-care analysis of lipid isomer biomarkers in complex samples.

Clinical features of NOTCH2NLC-related neuronal intranuclear inclusion disease.

BACKGROUND: Abnormal expanded GGC repeats within the NOTCH2HLC gene has been confirmed as the genetic mechanism for most Asian patients with neuronal intranuclear inclusion disease (NIID). This cross-sectional observational study aimed to characterise the clinical features of NOTCH2NLC-related NIID in China. METHODS: Patients with NOTCH2NLC-related NIID underwent an evaluation of clinical symptoms, a neuropsychological assessment, electrophysiological examination, MRI and skin biopsy. RESULTS: In the 247 patients with NOTCH2NLC-related NIID, 149 cases were sporadic, while 98 had a positive family history. The most common manifestations were paroxysmal symptoms (66.8%), autonomic dysfunction (64.0%), movement disorders (50.2%), cognitive impairment (49.4%) and muscle weakness (30.8%). Based on the initial presentation and main symptomology, NIID was divided into four subgroups: dementia dominant (n=94), movement disorder dominant (n=63), paroxysmal symptom dominant (n=61) and muscle weakness dominant (n=29). Clinical (42.7%) and subclinical (49.1%) peripheral neuropathies were common in all types. Typical diffusion-weighted imaging subcortical lace signs were more frequent in patients with dementia (93.9%) and paroxysmal symptoms types (94.9%) than in those with muscle weakness (50.0%) and movement disorders types (86.4%). GGC repeat sizes were negatively correlated with age of onset (r=-0.196, p<0.05), and in the muscle weakness-dominant type (median 155.00), the number of repeats was much higher than in the other three groups (p<0.05). In NIID pedigrees, significant genetic anticipation was observed (p<0.05) without repeat instability (p=0.454) during transmission. CONCLUSIONS: NIID is not rare; however, it is usually misdiagnosed as other diseases. Our results help to extend the known clinical spectrum of NOTCH2NLC-related NIID.

Rare variants in MYH15 modify amyotrophic lateral sclerosis risk.

Amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder characterized by progressive muscular atrophy and respiratory failure. The G4C2 repeat expansion in the C9orf72 gene is the most prevalent genetic risk for ALS. Mutation carriers (C9ALS) display variability in phenotypes such as age-at-onset and duration, suggesting the existence of additional genetic factors. Here we introduce a three-step gene discovery strategy to identify genetic factors modifying the risk of both C9ALS and sporadic ALS (sALS) using limited samples. We first identified 135 candidate genetic modifiers of C9ALS using whole-genome sequencing (WGS) of extreme C9ALS cases diagnosed ~30 years apart. We then performed an unbiased genetic screen using a Drosophila model of the G4C2 repeat expansion with the genes identified from WGS analysis. This genetic screen identified the novel genetic interaction between G4C2 repeat-associated toxicity and 18 genetic factors, suggesting their potential association with C9ALS risk. We went on to test if 14 out of the 18 genes, those which were not known to be risk factors for ALS previously, are also associated with ALS risk in sALS cases. Gene-based-statistical analyses of targeted resequencing and WGS were performed. These analyses together reveal that rare variants in MYH15 represent a likely genetic risk factor for ALS. Furthermore, we show that MYH15 could modulate the toxicity of dipeptides produced from expanded G4C2 repeat. Our study presented here demonstrates the power of combining WGS with fly genetics to facilitate the discovery of fundamental genetic components of complex traits with a limited number of samples.

Handheld Mass Spectrometer with Intelligent Adaptability for On-Site and Point-of-Care Analysis.

The development of miniature mass spectrometry (MS) systems with simple analysis procedures is important for the transition of applying MS analysis outside traditional analytical laboratories. Here, we present Mini 14, a handheld MS instrument with disposable sample cartridges designed based on the ambient ionization concept for intrasurgical tissue analysis and surface analysis. The instrumentation architecture consists of a single-stage vacuum chamber with a discontinuous atmospheric interface and a linear ion trap. A major effort in this study for technical advancement is on making handheld MS systems capable of automatically adapting to complex conditions for in-field analysis. Machine learning is used to establish the model for autocorrecting the mass offsets in the mass scale due to temperature variations and a new strategy is developed to extend the dynamic concentration range for analysis. Mini 14 weighs 12 kg and can operate on battery power for more than 3 h. The mass range exceeds m/z 2000, and the full peak width at half-maximum is Δm/z 0.4 at a scanning speed of 700 Th/s. The direct analysis of human brain tissue for identifying glioma associated with isocitrate dehydrogenase mutations has been achieved and a limit of detection of 5 ng/mL has been obtained for analyzing illicit drugs in blood.

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Alzheimer's disease (AD) is the most common senile neurodegenerative disease characterized by progressive cognitive dysfunction, psychological and behavioral abnormalities, and impaired ability of activities of daily living. A family with a total of 3 patients were admitted to the Department of Neurology of Xiangya Hospital, Central South University in 2018. The proband showed memory decline as the presenting symptoms, and subsequently showed psychological and behavioral abnormalities, personality changes, seizures, and motor retardation. Definite diagnosis of early-onset familial AD (EOFAD) with missense mutation of presenilin 2 (PSEN2) (c.715A>G p.M239V) was established by whole exome sequencing (WES) technology. We reported the mutation in Chinese Han population for the first time, which expanded the mutation spectrum ofPSEN2 gene and aid to enrich the characterization of clinical phenotype in EOFAD associated to PSEN2 mutations. Patients with early onset age and complex clinical manifestations of AD can be diagnosed with the help of genetic testing to avoid misdiagnosis.

Lack of association between LGMN and Alzheimer's disease in the Southern Han Chinese population.

Recently, functional studies have demonstrated that legumain (LGMN) cleaves both amyloid ß-protein precursor and tau, promoting senile plaques and formation of neurofibrillary tangles, which may play a crucial role in the pathogenesis of Alzheimer's disease (AD). However, the genetic role of LGMN in AD has not been clearly elucidated. Here, we used Sanger sequencing to investigate the single independent (single-variant association test) and cumulative (gene-based association test) effects of variants in the LGMN gene as potential susceptibility factors for AD, in a cohort comprising 676 AD cases and 365 elderly controls from the Han population of South China. In single-variant association analysis, none of the common variants in LGMN were statistically significant. In gene-based analysis, the LGMN gene also showed no association with AD. The results of our replication study in the Alzheimer's Disease Neuroimaging Initiative cohort also showed no association between LGMN and AD. These findings suggest that the LGMN gene may not be a critical factor for AD development.

Coimmunocapture and Electrochemical Quantitation of Total and Phosphorylated Amyloid-ß40 Monomers.

Phosphorylated proteins play important roles in the pathogenesis of Alzheimer's disease (AD). The most abundant constituent in AD's brain deposit is the amyloid-ß40 peptide (Aß40). Based on it, the degree of phosphorylated Aß40 in body fluids (e.g., cerebrospinal fluid, CSF), which is defined by the ratio of phosphorylated Aß40 to total Aß40 (pAß40/tAß40), is anticipated to be an index for early diagnosis of AD. The major challenge in pAß40/tAß40 detection is the large concentration difference between two Aß40 forms in the real samples, which usually requires multichannel equipment and complicated detection process. In this paper, we revealed the unexpected close affinities of the anti-Aß40 antibody to Aß40 (40.2 nM-1) and to pAß40 (42.3 nM-1). Based on it, a convenient coimmunocapture and electrochemical quantitation of tAß40 and pAß40 was achieved on an anti-Aß40 antibody immobilized Au electrode (anti-Aß40/Au). Once Aß40 and pAß40 were synchronously captured on the anti-Aß40/Au electrode, the tAß40 levels in CSF samples were quantified with electrochemical impedance spectroscopy. With the signal amplification from Cd2+/Ti4+-functionalized titanium phosphate nanospheres (Cd2+/Ti4+@TiP) which was selective conjugated to pAß40, concentrations of low abundant pAß40 as low as 1 fM were readily measured by square wave voltammetry. Our results reveal that despite the concentrations of tAß40 and pAß40 fluctuate in each individual case, the concentration ratios of pAß40/tAß40 in CSF samples from AD patients are significant larger than those from healthy donors. It demonstrates that the degree of phosphorylated Aß40 is hopeful to be an effective index for evaluating the AD progress and improving the accuracy of clinic AD diagnosis.

Light-Up Nonthiolated Aptasensor for Low-Mass, Soluble Amyloid-ß40 Oligomers at High Salt Concentrations.

Herein, a light-up nonthiolated aptasensor was developed for low-mass, soluble amyloid-ß40 oligomers (LS-Aß40-O). Au nanoparticles (AuNP) were employed as colorimetric probes, and the nonthiolated aptamers (Apt) were adsorbed on AuNP surfaces, acting as binding elements for LS-Aß40-O. The aggregation of AuNPs was induced when Apt-modified AuNPs (Apt@AuNPs) were under high-salt conditions. However, upon the addition of LS-Aß40-O into the Apt@AuNP solution, the salt tolerance of the AuNPs was greatly enhanced. Further studies confirmed that the formed LS-Aß40-O-Apt complex attached onto the AuNP surfaces via interactions between LS-Aß40-O and Au, which led to electrostatic and steric stabilization of the AuNPs under high-salt conditions. On the basis of this outcome, a sensitive light-up nonthiolated aptasensor for LS-Aß40-O was achieved with a detection limit of 10.0 nM and a linear range from 35.0 to 700 nM in a 175 mM NaCl solution. Cerebrospinal-fluid (CSF) samples from healthy persons and Alzheimer's disease (AD) patients were successfully distinguished by using this proposed method. The concentrations of LS-Aß40-O in the CSF of AD patients were of nanomolar grade, but there was no detectable LS-Aß40-O in those of the healthy persons. This work provides a new insight into the interaction between Apt@AuNPs and Aß40-O and also develops a simple, rapid, highly selective and sensitive, and applicable method for LS-Aß40-O detection in real CSF samples, which is significant for the diagnosis of AD.