MicroRNAs as Plasma Biomarkers of Hepatocellular Carcinoma in Patients with Liver Cirrhosis-A Cross-Sectional Study

Ultrasound screening for hepatocellular carcinoma (HCC) in patients with liver cirrhosis has a poor sensitivity for small tumors. Circulating microRNAs (miRNAs) have been explored as HCC biomarkers, but results are diverging. Here, we evaluate if miRNAs up-regulated in HCC tissue can be detected in plasma and used as screening biomarkers for HCC. In this cross-sectional study, plasma, HCC tissue and surrounding non-tumorous liver tissue were collected from liver resections. Tissue miRNAs were identified and quantitated by RNA-sequencing analysis, and the fold-changes between HCC and surrounding liver tissue were calculated. The miRNAs up-regulated in HCCs were then re-analyzed in plasma from the same patients, and the miRNAs with the highest plasma levels were subsequently measured in plasma from an independent cohort of patients with cirrhosis or HCC. In tissues from 84 resected patients, RNA-sequencing detected 197 differentially expressed miRNAs, 40 of which had a raw count above 200 and were analyzed in plasma from the same cohort. Thirty-one miRNAs were selected for further analysis in 200 patients with HCC or cirrhosis. Of these, eleven miRNAs were significantly increased in HCC as compared to cirrhosis patients. Only miR-93-5p and miR-151a-3p were significantly associated with HCC, with an AUC of 0.662. In comparison, alpha-fetoprotein and des-gamma-carboxy prothrombin yielded an AUC of 0.816, which increased to 0.832 if miR-93-5p and miR-151a-3p were added. When including sex and age, the addition of miR-93-5p and miR-151a-3p did not further improve the AUC (from 0.910 to 0.911). In conclusion, micro-RNAs up-regulated in HCCs are detectable in plasma but have a poor performance as screening biomarkers of HCC.

A Novel mRNA-Mediated and MicroRNA-Guided Approach to Specifically Eradicate Drug-Resistant Hepatocellular Carcinoma Cell Lines by Se-Methylselenocysteine

Despite progress in the treatment of non-visceral malignancies, the prognosis remains poor for malignancies of visceral organs and novel therapeutic approaches are urgently required. We evaluated a novel therapeutic regimen based on treatment with Se-methylselenocysteine (MSC) and concomitant tumor-specific induction of Kynurenine aminotransferase 1 (KYAT1) in hepatocellular carcinoma (HCC) cell lines, using either vector-based and/or lipid nanoparticle-mediated delivery of mRNA. Supplementation of MSC in KYAT1 overexpressed cells resulted in significantly increased cytotoxicity, due to ROS formation, as compared to MSC alone. Furthermore, microRNA antisense-targeted sites for miR122, known to be widely expressed in normal hepatocytes while downregulated in hepatocellular carcinoma, were added to specifically limit cytotoxicity in HCC cells, thereby limiting the off-target effects. KYAT1 expression was significantly reduced in cells with high levels of miR122 supporting the concept of miR-guided induction of tumor-specific cytotoxicity. The addition of alpha-ketoacid favored the production of methylselenol, enhancing the cytotoxic efficacy of MSC in HCC cells, with no effects on primary human hepatocytes. Altogether, the proposed regimen offers great potential to safely and specifically target hepatic tumors that are currently untreatable.

Rhesus Macaque Myeloid-Derived Suppressor Cells Demonstrate T Cell Inhibitory Functions and Are Transiently Increased after Vaccination

Myeloid-derived suppressor cells (MDSCs) are major regulators of T cell responses in several pathological conditions. Whether MDSCs increase and influence T cell responses in temporary inflammation, such as after vaccine administration, is unknown. Using the rhesus macaque model, which is critical for late-stage vaccine testing, we demonstrate that monocytic (M)-MDSCs and polymorphonuclear (PMN)-MDSCs can be detected using several of the markers used in humans. However, whereas rhesus M-MDSCs lacked expression of CD33, PMN-MDSCs were identified as CD33⁺ low-density neutrophils. Importantly, both M-MDSCs and PMN-MDSCs showed suppression of T cell proliferation in vitro. The frequency of circulating MDSCs rapidly and transiently increased 24 h after vaccine administration. M-MDSCs infiltrated the vaccine injection site, but not vaccine-draining lymph nodes. This was accompanied by upregulation of genes relevant to MDSCs such as arginase-1, IDO1, PDL1, and IL-10 at the injection site. MDSCs may therefore play a role in locally maintaining immune balance during vaccine-induced inflammation.

Induction of Robust B Cell Responses after Influenza mRNA Vaccination Is Accompanied by Circulating Hemagglutinin-Specific ICOS+ PD-1+ CXCR3+ T Follicular Helper Cells

Modified mRNA vaccines have developed into an effective and well-tolerated vaccine platform that offers scalable and precise antigen production. Nevertheless, the immunological events leading to strong antibody responses elicited by mRNA vaccines are largely unknown. In this study, we demonstrate that protective levels of antibodies to hemagglutinin were induced after two immunizations of modified non-replicating mRNA encoding influenza H10 encapsulated in lipid nanoparticles (LNP) in non-human primates. While both intradermal (ID) and intramuscular (IM) administration induced protective titers, ID delivery generated this response more rapidly. Circulating H10-specific memory B cells expanded after each immunization, along with a transient appearance of plasmablasts. The memory B cell pool waned over time but remained detectable throughout the 25-week study. Following prime immunization, H10-specific plasma cells were found in the bone marrow and persisted over time. Germinal centers were formed in vaccine-draining lymph nodes along with an increase in circulating H10-specific ICOS+ PD-1+ CXCR3+ T follicular helper cells, a population shown to correlate with high avidity antibody responses after seasonal influenza vaccination in humans. Collectively, this study demonstrates that mRNA/LNP vaccines potently induce an immunological repertoire associated with the generation of high magnitude and quality antibodies.

Pathological nociceptors in two patients with erythromelalgia-like symptoms and rare genetic Nav 1.9 variants

INTRODUCTION

The sodium channel Nav 1.9 is expressed in peripheral nociceptors and has recently been linked to human pain conditions, but the exact role of Nav 1.9 for human nociceptor excitability is still unclear.

METHODS

C-nociceptors from two patients with late onset of erythromelalgia-like pain, signs of small fiber neuropathy, and rare genetic variants of Nav 1.9 (N1169S, I1293V) were assessed by microneurography.

RESULTS

Compared with patients with comparable pain phenotypes (erythromelalgia-like pain without Nav-mutations and painful polyneuropathy), there was a tendency toward more activity-dependent slowing of conduction velocity in mechanoinsensitive C-nociceptors. Hyperexcitability to heating and electrical stimulation were seen in some nociceptors, and other unspecific signs of increased excitability, including spontaneous activity and mechanical sensitization, were also observed.

CONCLUSIONS

Although the functional roles of these genetic variants are still unknown, the microneurography findings may be compatible with increased C-nociceptor excitability based on increased Nav 1.9 function.

SCN10A Mutation in a Patient with Erythromelalgia Enhances C-Fiber Activity Dependent Slowing

Gain-of-function mutations in the tetrodotoxin (TTX) sensitive voltage-gated sodium channel (Nav) Nav1.7 have been identified as a key mechanism underlying chronic pain in inherited erythromelalgia. Mutations in TTX resistant channels, such as Nav1.8 or Nav1.9, were recently connected with inherited chronic pain syndromes. Here, we investigated the effects of the p.M650K mutation in Nav1.8 in a 53 year old patient with erythromelalgia by microneurography and patch-clamp techniques. Recordings of the patient’s peripheral nerve fibers showed increased activity dependent slowing (ADS) in CMi and less spontaneous firing compared to a control group of erythromelalgia patients without Nav mutations. To evaluate the impact of the p.M650K mutation on neuronal firing and channel gating, we performed current and voltage-clamp recordings on transfected sensory neurons (DRGs) and neuroblastoma cells. The p.M650K mutation shifted steady-state fast inactivation of Nav1.8 to more hyperpolarized potentials and did not significantly alter any other tested gating behaviors. The AP half-width was significantly broader and the stimulated action potential firing rate was reduced for M650K transfected DRGs compared to WT. We discuss the potential link between enhanced steady state fast inactivation, broader action potential width and the potential physiological consequences.

An Integrated Bioinformatics Approach for Identifying Genetic Markers that Predict Cerebrospinal Fluid Biomarker p-tau181/Aβ1-42 Ratio in ApoE4-Negative Mild Cognitive Impairment Patients

Alzheimer's disease (AD) is the most common form of dementia, with no disease-modifying treatment yet available. Early detection of patients at risk of developing AD is of central importance. Blood-based genetic signatures can serve as early detection and as population-based screening tools. In this study, we aimed to identify genetic markers and gene signatures associated with cerebrospinal fluid (CSF) biomarkers levels of t-tau, p-tau181, and with the two ratios t-tau/Aβ1-42 and p-tau181/Aβ1-42 in the context of progression from mild cognitive impairment (MCI) to AD, and to identify a panel of genetic markers that can predict CSF biomarker p-tau181/Aβ1-42 ratio with consideration of APOE ε4 stratification. We analyzed genome-wide the Alzheimer's Disease Neuroimaging Initiative dataset with up to 48 months follow-up. In the first part of the analysis, the main effect of single nucleotide polymorphisms (SNPs) under an additive genetic model was assessed for each of the four CSF biomarkers. In the second part of the analysis, we performed an integrated analysis of genome-wide association study results with pathway enrichment analysis, predictive modeling and network analysis in the subgroup of ApoE4-negative subjects. We identified a panel of five SNPs, rs6766238, rs1143960, rs1249963, rs11975968, and rs4836493, that are predictive for p-tau181/Aβ1-42 ratio (high/low) with a sensitivity of 66% and a specificity of 70% (AUC 0.74). These results suggest that a panel of SNPs is a potential prognostic biomarker in ApoE4-negative MCI patients.

Revolutionizing Alzheimer's disease and clinical trials through biomarkers

The Alzheimer's Association's Research Roundtable met in May 2014 to explore recent progress in developing biomarkers to improve understanding of disease pathogenesis and expedite drug development. Although existing biomarkers have proved extremely useful for enrichment of subjects in clinical trials, there is a clear need to develop novel biomarkers that are minimally invasive and that more broadly characterize underlying pathogenic mechanisms, including neurodegeneration, neuroinflammation, and synaptic dysfunction. These may include blood-based assays and new neuropsychological testing protocols, as well as novel ligands for positron emission tomography imaging, and advanced magnetic resonance imaging methodologies. In addition, there is a need for biomarkers that can serve as theragnostic markers of response to treatment. Standardization remains a challenge, although international consortia have made substantial progress in this area and provide lessons for future standardization efforts.

Exonic mutations in SCN9A (NaV1.7) are found in a minority of patients with erythromelalgia

Background and aim

“Gain-of-function” mutations in voltage-gated sodium channel NaV1.7 have been linked to erythromelalgia (EM), characterized by painful hot and red hands and feet. We investigated the proportion of patients with EM that carry a mutation in NaV1.7 or in other pain-related genes and studied possible clinical differences.

Methods

In this study, 48 patients with EM were screened for mutations in a total of 29 candidate genes, including all sodium channel subunits, transient receptor potential channels (TRPA1, TRPV1, TRPM8), neurotrophic factors (NGF, NGFR, BDNF, GDNF, NTRK1 and WNK1) and other known pain-related genes (CACNG2, KCNS1, COMT, P2RX3, TAC1, TACR1), using a combination of next generation sequencing and classical Sanger sequencing.

Results

In 7/48 patients protein-modifying mutations of NaV1.7 (P187L, I228M, I848T (n = 4) and N1245S) were identified. Patients with the I848T mutation could be identified clinically based on early onset and severity of the disease. In contrast, there were no clinical characteristics that differentiated the other patients with NaV1.7 mutation from those patients without. We also found more than twenty rare protein-modifying genetic variants in the genes coding for sodium channels (NaV1.8, NaV1.9, NaV1.6, NaV1.5, NaV2.1, SCN1B, SCN3B), transient receptor potential channel (TRPA1, TRPV1), and other pain-related targets (WNK1 and NGFR).

Conclusion

We conclude that functionally characterized mutations of NaV1.7 (I848T) are present only in a minority of patient with EM. Albeit the majority of patients (27/48) carried rare protein-modifying mutations the vast majority of those will most probably not be causally linked to their disease.

Implications

The key question remaining to be solved is the possible role of rare variants of NaV1.8, NaV1.9, or beta-subunits in provoking chronic pain conditions or even EM.

Biomarkers: refining diagnosis and expediting drug development - reality, aspiration and the role of open innovation

In the last decade, there have been intensive efforts to invent, qualify and use novel biomarkers as a means to improve success rates in drug discovery and development. The biomarkers field is maturing and this article considers whether these research efforts have brought about the expected benefits. The characteristics of a clinically useful biomarker are described and the impact this area of research has had is evaluated by reviewing a few, key examples of emerging biomarkers. There is evidence that the impact has been genuine and is increasing in both the drug and the diagnostic discovery and development processes. Beneficial impact on patient health outcomes seems relatively limited thus far, with the greatest impact in oncology (again, both in terms of novel drugs and in terms of more refined diagnoses and therefore more individualized treatment). However, the momentum of research would indicate that patient benefits are likely to increase substantially and to broaden across multiple therapeutic areas. Even though this research was originally driven by a desire to improve the drug discovery and development process, and was therefore funded with this aim in mind, it seems likely that the largest impact may actually come from more refined diagnosis. Refined diagnosis will facilitate both better allocation of healthcare resources and the use of treatment regimens which are optimized for the individual patient. This article also briefly reviews emerging technological approaches and how they relate to the challenges inherent in biomarker discovery and validation, and discusses the role of public/private partnerships in innovative biomarker research.

Possible allelic structure of IgG2a and IgG2c in mice

Earlier publication suggested that IgG2a and IgG2c (coding for Igh-1a and Igh-1b) are organized in tandem on the same chromosome as two distinct loci in mice. Our data suggest that IgG2a and IgG2c are not physically linked on the chromosome and are allelic - single locus in majority strains of mice. In another word, IgG2b-IgG2c-IgG2a haplotype proposed by Morgado et al. (1989) may exist in some strains of mice, but IgG2b-IgG2a and IgG2b-IgG2c are likely to be most common haplotypes in mice. Therefore, inbred mice may produce different IgG2a isotypes dependent on their origin (strain); C57B/6 and SJL mice secrete IgG2c while NMRI and DBA/2 mice secrete IgG2a only. The situation is more complicated for Swiss Webster mice (outbred) and Alzheimer's disease transgenic (AD/Tg) mice with multi-genetic backgrounds; mice may secrete only IgG2a, or IgG2c, or both IgG2a and IgG2c. IgG2a and IgG2c likely have different immune profile (response, immune-decoration) in mice due to their divergence of protein sequence. If antibodies based on IgG2a (or IgG2c) are used in chronic studies for preclinical evaluation of antibody efficacy, characterization of IgG2a isotypes in advance becomes critical in the design of such biopharmaceutical projects in order to avoid immune response.

Short-time gene expression response to valproic acid and valproic acid analogs in mouse embryonic stem cells

Prediction of developmental toxicity in vitro could be based on short-time toxicogenomic endpoints in embryo-derived cell lines. Microarray studies in P19 mouse embryocarcinoma cells and mouse embryos have indicated that valproic acid (VPA), an inducer of neural tube defects, deregulates the expression of many genes, including those critically involved in neural tube development. In this study, we exposed undifferentiated R1 mouse embryonic stem cells to VPA and VPA analogs for 6 h and used CodeLink whole-genome expression microarrays to define VPA-responsive genes correlating with teratogenicity. Compared with the nonteratogenic analog 2-ethyl-4-methylpentanoic acid, VPA and the teratogenic VPA analog (S)-2-pentyl-4-pentynoic acid deregulated a much larger number of genes. Five genes (of ∼2500 array probes correlating with the separation) were sufficient to effectively separate teratogens from nonteratogens. A large fraction of the target genes correlating with teratogenicity are functionally related to embryonic development and morphogenesis, including neural tube formation and closure. Similar responses in R1 were found for most genes previously identified as VPA responsive in P19 and embryos. A subset of target genes was evaluated as candidate markers predictive of potential teratogenicity against a range of known teratogens using TaqMan expression arrays. These marker genes showed a positive predictive value for the teratogens butyrate and trichostatin A, which like VPA and (S)-2-pentyl-4-pentynoic acid are known histone deacetylase (HDAC) inhibitors but not for compounds that are likely to act by other mechanisms. This indicates that HDAC inhibition may be a major mechanism by which VPA induces gene deregulation and possibly teratogenicity.

Early transcriptional responses in mouse embryos as a basis for selection of molecular markers predictive of valproic acid teratogenicity

Cell-based in vitro assays would potentially reduce animal testing in preclinical drug development. Mouse embryos exposed to the teratogenic drug valproic acid (VPA) in utero for 1.5, 3 or 6h on gestational day 8 were analyzed using microarrays. Significant effects on gene expression were observed already at 1.5h, and 85 probes were deregulated across all time points. To find transcriptional markers of VPA-induced developmental toxicity, the in vivo data were compared to previous in vitro data on embryonal carcinoma P19 cells exposed to VPA for 1.5, 6 or 24h. Maximal concordance between embryos and cells was at the 6-h time points, with 163 genes showing similar deregulation. Developmentally important Gene Ontology terms, such as "organ morphogenesis" and "tube development" were overrepresented among putative VPA target genes. The genes Gja1, Hap1, Sall2, H1f0,Cyp26a1, Fgf15, Otx2, and Lin7b emerged as candidate in vitro markers of potential VPA-induced teratogenicity.

Correlation network analysis for data integration and biomarker selection

High-throughput biomolecular profiling techniques such as transcriptomics, proteomics and metabolomics are increasingly being used in in vivo studies to recognize and characterize effects of xenobiotics on organs and systems. Of particular interest are biomarkers of treatment-related effects which are detectable in easily accessible biological fluids such as blood. A fundamental challenge in such biomarker studies is selecting among the plethora of biomolecular changes induced by a compound and revealed by molecular profiling, to identify biomarkers which are exclusively or predominantly due to specific processes. In this work we present a cross-compartment correlation network approach, involving no a priori supervision or design, to integrate proteomic, metabolomic and transcriptomic data for selecting circulating biomarkers. The case study we present is the identification of biomarkers of drug-induced hepatic toxicity effects in a rodent model. Biomolecular profiling of both blood plasma and liver tissue from Wistar Hannover rats administered a toxic compound yielded many hundreds of statistically significant molecular changes. We exploited drug-induced correlations between blood plasma analytes and liver tissue molecules across study animals in order to nominate selected plasma molecules as biomarkers of drug-induced hepatic alterations of lipid metabolism and urea cycle processes.

Variation in interleukin 7 receptor alpha chain (IL7R) influences risk of multiple sclerosis

Multiple sclerosis is a chronic, often disabling, disease of the central nervous system affecting more than 1 in 1,000 people in most western countries. The inflammatory lesions typical of multiple sclerosis show autoimmune features and depend partly on genetic factors. Of these genetic factors, only the HLA gene complex has been repeatedly confirmed to be associated with multiple sclerosis, despite considerable efforts. Polymorphisms in a number of non-HLA genes have been reported to be associated with multiple sclerosis, but so far confirmation has been difficult. Here, we report compelling evidence that polymorphisms in IL7R, which encodes the interleukin 7 receptor alpha chain (IL7Ralpha), indeed contribute to the non-HLA genetic risk in multiple sclerosis, demonstrating a role for this pathway in the pathophysiology of this disease. In addition, we report altered expression of the genes encoding IL7Ralpha and its ligand, IL7, in the cerebrospinal fluid compartment of individuals with multiple sclerosis.

A stop codon mutation in SCN9A causes lack of pain sensation

The general lack of pain experience is a rare occurrence in humans, and the molecular causes for this phenotype are not well understood. Here we have studied a Canadian family from Newfoundland with members who exhibit a congenital inability to experience pain. We have mapped the locus to a 13.7 Mb region on chromosome 2q (2q24.3-2q31.1). Screening of candidate genes in this region identified a protein-truncating mutation in SCN9A, which encodes for the voltage-gated sodium channel Na(v)1.7. The mutation is a C-A transversion at nucleotide 984 transforming the codon for tyrosine 328 to a stop codon. The predicted product lacks all pore-forming regions of Na(v)1.7. Indeed, expression of this altered gene in a cell line did not produce functional responses, nor did it cause compensatory effects on endogenous voltage-gated sodium currents when expressed in ND7/23 cells. Because a homozygous knockout of Na(v)1.7 in mice has been shown to be lethal, we explored why a deficiency of Na(v)1.7 is non-lethal in humans. Expression studies in monkey, human, mouse and rat tissue indicated species-differences in the Na(v)1.7 expression profile. Whereas in rodents the channel was strongly expressed in hypothalamic nuclei, only weak mRNA levels were detected in this area in primates. Furthermore, primate pituitary and adrenal glands were devoid of signal, whereas these two glands were mRNA-positive in rodents. This species difference may explain the non-lethality of the observed mutation in humans. Our data further establish Na(v)1.7 as a critical element of peripheral nociception in humans.

An association study of two functional promotor polymorphisms in the myeloperoxidase (MPO) gene in multiple sclerosis

Multiple sclerosis (MS) is a chronic neurological disease affecting the central nervous system (CNS). The disease is characterised by demyelination and axonal loss caused by abnormal immunological responses resulting in accumulating neurological disabilities. MS is considered a complex disease, with both genetic and environmental factors contributing to the pathogenesis. In this study, we have investigated the genetic role of the myeloperoxidase (MPO) gene encoding myeloperoxidase in MS. MPO is an enzyme found in myeloid cells which catalyses the production of hypochlorus acid, a potent microbicidal agent. It also plays an important role in inflammatory processes, where migrating neutrophiles may release active MPO and cause tissue damage. In this study, we investigated two polymorphisms located in the promotor region of the MPO gene, known to influence the expression of MPO, in a large case/control material consisting of 871 Swedish MS patients and 532 Swedish healthy controls. No association was observed with risk of MS. Multiple Sclerosis 2007; 13: 697-700. http://msj.sagepub.com

Association analysis of the LAG3 and CD4 genes in multiple sclerosis in two independent populations

We have investigated the genetic involvement of the CD4 and the LAG3 genes, two appealing candidates for MS due to their suggested role in MS pathology. We genotyped a Swedish case-control material consisting of 920 MS patients and 778 controls in an initial study of CD4, three SNPs showed a significant association with MS. An independent material consisting of 1720 Nordic MS patients and 1416 controls were used for confirmation of associated markers in CD4 and to do a confirmative study of the LAG3 gene from previous findings. The result, including a total of 2640 MS patients and 2194 controls shows no significant association with CD4 and LAG3 and MS. We conclude that these genes are of minor importance in regard of genetic predisposition to the MS.

Two genes encoding immune-regulatory molecules (LAG3 and IL7R) confer susceptibility to multiple sclerosis

Multiple sclerosis (MS) is a T-cell-mediated disease of the central nervous system, characterized by damage to myelin and axons, resulting in progressive neurological disability. Genes may influence susceptibility to MS, but results of association studies are inconsistent, aside from the identification of HLA class II haplotypes. Whole-genome linkage screens in MS have both confirmed the importance of the HLA region and uncovered non-HLA loci that may harbor susceptibility genes. In this two-stage analysis, we determined genotypes, in up to 672 MS patients and 672 controls, for 123 single-nucleotide polymorphisms (SNPs) in 66 genes. Genes were chosen based on their chromosomal positions or biological functions. In stage one, 22 genes contained at least one SNP for which the carriage rate for one allele differed significantly (P<0.08) between patients and controls. After additional genotyping in stage two, two genes--each containing at least three significantly (P<0.05) associated SNPs--conferred susceptibility to MS: LAG3 on chromosome 12p13, and IL7R on 5p13. LAG3 inhibits activated T cells, while IL7R is necessary for the maturation of T and B cells. These results imply that germline allelic variation in genes involved in immune homeostasis--and, by extension, derangement of immune homeostasis--influence the risk of MS.

Genetic structure adds power to detect schizophrenia susceptibility at SLIT3 in the Chinese Han population

The Chinese Han population, the largest population in the world, has traditionally been geographically divided into two parts, the Southern Han and Northern Han. In practice, however, these commonly used ethnic labels are both insufficient and inaccurate as descriptors of inferred genetic clustering, and can lead to the observation of "spurious association" as well as the concealment of real association. In this study, we attempted to address this problem by using 14 microsatellite markers to reconstruct the population genetic structure in 768 Han Chinese samples, including 384 Southern Han and 384 Northern Han, and in samples from Chinese minorities including 48 Yao and 48 BouYei subjects. Furthermore, with a dense set of markers around the region 5q34-35, we built fine-scale haplotype networks for each population/subpopulation and tested for association to schizophrenia susceptibility. We found that more variants in SLIT3 tend to associate with schizophrenia susceptibility in the genetically structured samples, compared to geographically structured samples and samples without identified population substructure. Our results imply that identifying the hidden genetic substructure adds power when detecting association, and suggest that SLIT3 or a nearby gene is associated with schizophrenia.

CTLA4 dimorphisms and the multiple sclerosis phenotype

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), expressed on activated T cells, binds to B7 molecules on antigen-presenting cells. Signaling via CTLA-4 results in downregulation of ongoing T-cell clonal expansion. A single-nucleotide polymorphism (SNP) in exon 1 of CTLA4 is associated with susceptibility to several autoimmune diseases, including multiple sclerosis (MS). In this two-stage study, we investigated whether haplotypes composed of exon 1-SNP alleles and alleles of a promoter-region SNP influence age at onset, disease severity and disease course in MS. In stage 1, deviations in CTLA4 haplotype frequencies were observed in patients subgrouped by course; in stage 2, none of these original associations were confirmed.

APOE genotypes and disease severity in multiple sclerosis

Apolipoprotein E (opoE) is involved in the transport of lipids necessary for membrane repair and is encoded by a gene on chromosome 19q13, a region positive for linkage in two multiple sclerosis (MS) genome-wide screens. The APOE epsilon4 allele confers susceptibility to both familial and sporadic Alzheimer's disease (AD). Carriage of epsilon4 is associated with defective dendritic remodeling in AD, and with unfavorable clinical outcome in head trauma and cerebrovascular disease. According to the results of previous studies, APOE epsilon4 does not increase the risk of developing MS, but it may influence disease progression and ultimate disability. From a total cohort of over 900 MS patients, we compared APOE epsilon2-4 genotypes in, roughly, the cohort's least disabled and most disabled septiles. 'Benign MS' (n=124) was defined as an Expanded Disability Status Scale (EDSS) score of 3.0 or less, despite at least 10 years of disease duration, and 'severe MS' (n=140) as the attainment of an EDSS score of 6.0 within 8 years of disease onset. We found no significant differences in genotype or phenotype frequencies between the benign-MS and severe-MS septiles; however, the risk conferred by epsilon4 rose progressively upon comparison of carriage rates in more narrowly defined anti-podal quantiles.