Assessment of Association between NINJ2 Polymorphisms and Suicide Attempts in an Iranian Population.

Suicidal behavior as a psychological problem with high public health burden is associated with a number of genetically determined risk factors. In the current study, we investigated the association between two polymorphisms within the NINJ2 gene and risk of suicide in an Iranian population. The study included 295 individuals who attempted suicide with soft suicide methods, 234 suicide victims and 410 normal controls. The rs11833579 SNP was associated with death from suicide in a codominant model in that the AG genotype decreased the risk of death from suicide compared with the GG genotype (OR (95% CI) = 0.49 (0.34-0.71), adjusted P value = 4e-04). This SNP was also associated with death from suicide in dominant (AG + AA versus GG: OR (95% CI) = 0.63 (0.46-0.87), adjusted P value = 0.011) and overdominant (AG versus GG + AA: OR (95% CI) = 0.49 (0.35-0.69), adjusted P value < 0.0001) models. In addition, this SNP was associated with soft suicide attempts in a codominant model (AG versus AA + GG: OR (95% CI) = 0.7 (0.5-0.98), adjusted P value = 0.02). The rs3806263 SNP was associated with death from suicide in allelic (A versus G: OR (95% CI) = 1.48 (1.17-1.88), adjusted P value = 0.002), codominant (AA versus GG: OR (95% CI) = 3.14 (1.89-5.21), adjusted P value < 0.0001), recessive (AA versus GG + AG: OR (95% CI) = 3.47 (2.15-5.61), adjusted P value < 0.0001), overdominant (AG versus AA + GG: OR (95% CI) = 0.62 (0.45-0.87), adjusted P value = 0.0092) and log-additive models (OR (95% CI) = 1.45 (1.15-1.83), adjusted P value = 0.0034). When comparing allele/genotype frequencies of this SNP between suicide victims and soft suicide attempters, significant associations were found in allelic, codominant, recessive and log-additive models. The AG haplotype (rs11833579 and rs3806263, respectively) was significantly less prevalent among suicide victims compared with controls (OR (95% CI) = 0.37 (0.26-0.52), adjusted P value < 0.0001). This haplotype was also less prevalent among suicide victims vs. soft suicide attempters (OR (95% CI) = 0.43 (0.31-0.61), adjusted P value < 0.0001). The GA haplotype (rs11833579 and rs3806263, respectively) was less frequent among suicide victims compared with controls (OR (95% CI) = 0.63 (0.45-0.89), adjusted P value = 0.0156). Finally, the AA haplotype was more prevalent among suicide victims compared with both controls (OR (95% CI) = 2.37 (1.56-3.6), adjusted P value = 0.0002) and soft suicide attempters (OR (95% CI) = 1.92 (1.32-2.78), adjusted P value = 0.0012). Thus, these two SNPs might be regarded as genetic determinants of suicide risk in Iranian populations. Further studies in different populations are needed to verify these results.

Identification of novel common variants associated with chronic pain using conditional false discovery rate analysis with major depressive disorder and assessment of pleiotropic effects of LRFN5.

Chronic pain is a complex trait that is moderately heritable and genetically, as well as phenotypically, correlated with major depressive disorder (MDD). Use of the conditional false discovery rate (cFDR) approach, which leverages pleiotropy identified from existing GWAS outputs, has been successful in discovering novel associated variants in related phenotypes. Here, genome-wide association study outputs for both von Korff chronic pain grade and for MDD were used to identify variants meeting a cFDR threshold for each outcome phenotype separately, as well as a conjunctional cFDR (ccFDR) threshold for both phenotypes together. Using a moderately conservative threshold, we identified a total of 11 novel single nucleotide polymorphisms (SNPs), six of which were associated with chronic pain grade and nine of which were associated with MDD. Four SNPs on chromosome 14 were associated with both chronic pain grade and MDD. SNPs associated only with chronic pain grade were located within SLC16A7 on chromosome 12. SNPs associated only with MDD were located either in a gene-dense region on chromosome 1 harbouring LINC01360, LRRIQ3, FPGT and FPGT-TNNI3K, or within/close to LRFN5 on chromosome 14. The SNPs associated with both outcomes were also located within LRFN5. Several of the SNPs on chromosomes 1 and 14 were identified as being associated with expression levels of nearby genes in the brain and central nervous system. Overall, using the cFDR approach, we identified several novel genetic loci associated with chronic pain and we describe likely pleiotropic effects of a recently identified MDD locus on chronic pain.

Assessment of expression of RELN signaling pathway in multiple sclerosis patients.

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system. Nearly 85% of MS patients are recognized with relapsing-remitting MS (RRMS), a typical clinical course of disease which is distinguished by several episodes of relapses, separated by remissions of neurological impairment. Failure of repair mechanisms is a main factor in progression of neurological dysfunction in MS. Several lines of evidence suggest that Reelin (RELN) signaling pathway can contribute in the regulation of repair mechanisms in MS patients. In the present study, we assessed expression levels of RELN and Disabled-1 (DAB1), two key genes in RELN signaling pathway, in peripheral blood of 50 RRMS patients and 50 matched healthy subjects. RELN was significantly down-regulated in total MS patients, and total female patients compared with the matched controls. However, no statistically significant difference was found in DAB1 mRNA expression between MS patients and controls. Furthermore, considerable correlations were detected between expression levels of RELN and DAB1 in the patients group. There were no significant correlations between expression levels of genes and EDSS, disease duration or age at onset. Our study provides evidences for the role of RELN signaling pathway in the pathogenesis of MS. Further studies are required to clarify the exact clinical significance of this pathway in MS patients.

Clinicopathological case: progressive somnolence and dementia in an accountant: when the shine rubs off the gold standard.

A 63-year-old accountant developed progressive somnolence, cognitive decline, gait disturbance and cerebellar dysfunction with autonomic features. This report documents the clinicopathological conference at the 39th Edinburgh Advanced Neurology Course 2017.

Assessment of the quality of DNA from various formalin-fixed paraffin-embedded (FFPE) tissues and the use of this DNA for next-generation sequencing (NGS) with no artifactual mutation.

Formalin-fixed, paraffin-embedded (FFPE) tissues used for pathological diagnosis are valuable for studying cancer genomics. In particular, laser-capture microdissection of target cells determined by histopathology combined with FFPE tissue section immunohistochemistry (IHC) enables precise analysis by next-generation sequencing (NGS) of the genetic events occurring in cancer. The result is a new strategy for a pathological tool for cancer diagnosis: 'microgenomics'. To more conveniently and precisely perform microgenomics, we revealed by systematic analysis the following three details regarding FFPE DNA compared with paired frozen tissue DNA. 1) The best quality of FFPE DNA is obtained by tissue fixation with 10% neutral buffered formalin for 1 day and heat treatment of tissue lysates at 95°C for 30 minutes. 2) IHC staining of FFPE tissues decreases the quantity and quality of FFPE DNA to one-fourth, and antigen retrieval (at 120°C for 15 minutes, pH 6.0) is the major reason for this decrease. 3) FFPE DNA prepared as described herein is sufficient for NGS. For non-mutated tissue specimens, no artifactual mutation occurs during FFPE preparation, as shown by precise comparison of NGS of FFPE DNA and paired frozen tissue DNA followed by validation. These results demonstrate that even FFPE tissues used for routine clinical diagnosis can be utilized to obtain reliable NGS data if appropriate conditions of fixation and validation are applied.

LRRTMs and neuroligins bind neurexins with a differential code to cooperate in glutamate synapse development.

Leucine-rich repeat transmembrane neuronal proteins (LRRTMs) were recently found to instruct presynaptic and mediate postsynaptic glutamatergic differentiation. In a candidate screen, here we identify neurexin-1beta lacking an insert at splice site 4 (-S4) as a ligand for LRRTM2. Neurexins bind LRRTM2 with a similar affinity but distinct code from the code for binding neuroligin-1 (the predominant form of neuroligin-1 at glutamate synapses, containing the B splice site insert). Whereas neuroligin-1 binds to neurexins 1, 2, and 3 beta but not alpha variants, regardless of insert at splice site 4, LRRTM2 binds to neurexins 1, 2, and 3 alpha and beta variants specifically lacking an insert at splice site 4. We further show that this binding code is conserved in LRRTM1, the family member linked to schizophrenia and handedness, and that the code is functional in a coculture hemisynapse formation assay. Mutagenesis of LRRTM2 to prevent binding to neurexins abolishes presynaptic inducing activity of LRRTM2. Remarkably, mutagenesis of neurexins shows that the binding face on neurexin-1beta (-S4) is highly overlapping for the structurally distinct LRRTM2 and neuroligin-1 partners. Finally, we explore here the interplay of neuroligin-1 and LRRTM2 in synapse regulation. In neuron cultures, LRRTM2 is more potent than neuroligin-1 in promoting synaptic differentiation, and, most importantly, these two families of neurexin-binding partners cooperate in an additive or synergistic manner. Thus, we propose a synaptic code hypothesis suggesting that neurexins are master regulators of the cooperative activities of LRRTMs and neuroligins.

Assessment of cognitive function in the heterozygous reeler mouse.

RATIONALE: The heterozygous reeler mouse has been proposed as a genetic mouse model of schizophrenia based on several neuroanatomical and behavioral similarities between these mice and patients with schizophrenia. However, the effect of reelin haploinsufficiency on one of the cardinal symptoms of schizophrenia, the impairment of prefrontal-cortex-dependent cognitive function, has yet to be determined. OBJECTIVE: Here, we investigated multiple aspects of cognitive function in heterozygous reeler mice that are known to be impaired in schizophrenic patients. METHODS: Heterozygous reeler mice were assessed for (1) cognitive flexibility in an instrumental reversal learning task, (2) impulsivity in an inhibitory control task, (3) attentional function in a three-choice serial reaction time task, and (4) working memory in a delayed matching-to-position task. RESULTS: No differences were found between heterozygous reeler mice and wild-type littermate controls in any prefrontal-related cognitive measures. However, heterozygous reeler mice showed deficits in the acquisition of two operant tasks, consistent with a role for reelin in certain forms of learning. CONCLUSIONS: These findings suggest that heterozygous reeler mice may not be an appropriate model for the core prefrontal-dependent cognitive deficits observed in schizophrenia, but may model more general learning deficits that are associated with many psychiatric disorders.

Immunoglobulin superfamily proteins in Caenorhabditis elegans.

The predicted proteins of the genome of Caenorhabditis elegans were analysed by various sequence comparison methods to identify the repertoire of proteins that are members of the immunoglobulin superfamily (IgSF). The IgSF is one of the largest families of protein domain in this genome and likely to be one of the major families in other multicellular eukaryotes too. This is because members of the superfamily are involved in a variety of functions including cell-cell recognition, cell-surface receptors, muscle structure and, in higher organisms, the immune system. Sixty-four proteins with 488 I set IgSF domains were identified largely by using Hidden Markov models. The domain architectures of the protein products of these 64 genes are described. Twenty-one of these had been characterised previously. We show that another 25 are related to proteins of known function. The C. elegans IgSF proteins can be classified into five broad categories: muscle proteins, protein kinases and phosphatases, three categories of proteins involved in the development of the nervous system, leucine-rich repeat containing proteins and proteins without homologues of known function, of which there are 18. The 19 proteins involved in nervous system development that are not kinases or phosphatases are homologues of neuroglian, axonin, NCAM, wrapper, klingon, ICCR and nephrin or belong to the recently identified zig gene family. Out of the set of 64 genes, 22 are on the X chromosome. This study should be seen as an initial description of the IgSF repertoire in C. elegans, because the current gene definitions may contain a number of errors, especially in the case of long sequences, and there may be IgSF genes that have not yet been detected. However, the proteins described here do provide an overview of the bulk of the repertoire of immunoglobulin superfamily members in C. elegans, a framework for refinement and extension of the repertoire as gene and protein definitions improve, and the basis for investigations of their function and for comparisons with the repertoires of other organisms.