High density SNP association study of a major autism linkage region on chromosome 17

Multivariate GWAS of Alzheimer's disease CSF biomarker profiles implies GRIN2D in synaptic functioning

BACKGROUND

Genome-wide association studies (GWAS) of Alzheimer's disease (AD) have identified several risk loci, but many remain unknown. Cerebrospinal fluid (CSF) biomarkers may aid in gene discovery and we previously demonstrated that six CSF biomarkers (β-amyloid, total/phosphorylated tau, NfL, YKL-40, and neurogranin) cluster into five principal components (PC), each representing statistically independent biological processes. Here, we aimed to (1) identify common genetic variants associated with these CSF profiles, (2) assess the role of associated variants in AD pathophysiology, and (3) explore potential sex differences.

METHODS

We performed GWAS for each of the five biomarker PCs in two multi-center studies (EMIF-AD and ADNI). In total, 973 participants (n = 205 controls, n = 546 mild cognitive impairment, n = 222 AD) were analyzed for 7,433,949 common SNPs and 19,511 protein-coding genes. Structural equation models tested whether biomarker PCs mediate genetic risk effects on AD, and stratified and interaction models probed for sex-specific effects.

RESULTS

Five loci showed genome-wide significant association with CSF profiles, two were novel (rs145791381 [inflammation] and GRIN2D [synaptic functioning]) and three were previously described (APOE, TMEM106B, and CHI3L1). Follow-up analyses of the two novel signals in independent datasets only supported the GRIN2D locus, which contains several functionally interesting candidate genes. Mediation tests indicated that variants in APOE are associated with AD status via processes related to amyloid and tau pathology, while markers in TMEM106B and CHI3L1 are associated with AD only via neuronal injury/inflammation. Additionally, seven loci showed sex-specific associations with AD biomarkers.

CONCLUSIONS

These results suggest that pathway and sex-specific analyses can improve our understanding of AD genetics and may contribute to precision medicine.

Chronic methamphetamine interacts with BDNF Val66Met to remodel psychosis pathways in the mesocorticolimbic proteome

Methamphetamine (Meth) abuse has reached epidemic proportions in many countries and can induce psychotic episodes mimicking the clinical profile of schizophrenia. Brain-derived neurotrophic factor (BDNF) is implicated in both Meth effects and schizophrenia. We therefore studied the long-term effects of chronic Meth exposure in transgenic mice engineered to harbor the human BDNF^Val66Met polymorphism expressed via endogenous mouse promoters. These mice were chronically treated with an escalating Meth regime during late adolescence. At least 4 weeks later, all hBDNF^Val66Met Meth-treated mice exhibited sensitization confirming persistent behavioral effects of Meth. We used high-resolution quantitative mass spectrometry-based proteomics to biochemically map the long-term effects of Meth within the brain, resulting in the unbiased detection of 4808 proteins across the mesocorticolimbic circuitry. Meth differentially altered dopamine signaling markers (e.g., Dat, Comt, and Th) between hBDNF^Val/Val and hBDNF^Met/Met mice, implicating involvement of BDNF in Meth-induced reprogramming of the mesolimbic proteome. Targeted analysis of 336 schizophrenia-risk genes, as well as 82 growth factor cascade markers, similarly revealed that hBDNF^Val66Met genotype gated the recruitment of these factors by Meth in a region-specific manner. Cumulatively, these data represent the first comprehensive analysis of the long-term effects of chronic Meth exposure within the mesocorticolimbic circuitry. In addition, these data reveal that long-term Meth-induced brain changes are strongly dependent upon BDNF genetic variation, illustrating how drug-induced psychosis may be modulated at the molecular level by a single genetic locus.

Hippocampal LASP1 ameliorates chronic stress-mediated behavioral responses in a mouse model of unpredictable chronic mild stress

Substantial evidence has revealed that abnormalities in synaptic plasticity play important roles during the process of depression. LASP1 (LIM and SH3 domain protein 1), a member of actin-binding proteins, has been shown to be associated with the regulation of synaptic plasticity. However, the role of LASP1 in the regulation of mood is still unclear. Here, using an unpredictable chronic mild stress (UCMS) paradigm, we found that the mRNA and protein levels of LASP1 were decreased in the hippocampus of stressed mice and that UCMS-induced down-regulation of LASP1 was abolished by chronic administration of fluoxetine. Adenosine-associated virus-mediated hippocampal LASP1 overexpression alleviated the UCMS-induced behavioral results of forced swimming test and sucrose preference test in stressed mice. It also restored the dendritic spine density, elevated the levels of AKT (a serine/threonine protein kinase), phosphorylated-AKT, insulin-like growth factor 2, and postsynaptic density protein 95. These findings suggest that LASP1 alleviates UCMS-provoked behavioral defects, which may be mediated by an enhanced dendritic spine density and more activated AKT-dependent LASP1 signaling, pointing to the antidepressant role of LASP1.

Evaluation of Chromosome Microarray Analysis in a Large Cohort of Females with Autism Spectrum Disorders: A Single Center Italian Study

Autism spectrum disorders (ASD) encompass a heterogeneous group of neurodevelopmental disorders resulting from the complex interaction between genetic and environmental factors. Thanks to the chromosome microarray analysis (CMA) in clinical practice, the accurate identification and characterization of submicroscopic deletions/duplications (copy number variants, CNVs) associated with ASD was made possible. However, the widely acknowledged excess of males on the autism spectrum reflects on a paucity of CMA studies specifically focused on females with ASD (f-ASD). In this framework, we aim to evaluate the frequency of causative CNVs in a single-center cohort of idiopathic f-ASD. Among the 90 f-ASD analyzed, we found 20 patients with one or two potentially pathogenic CNVs, including those previously associated with ASD (located at 16p13.2 16p11.2, 15q11.2, and 22q11.21 regions). An exploratory genotype/phenotype analysis revealed that the f-ASD with causative CNVs had statistically significantly lower restrictive and repetitive behaviors than those without CNVs or with non-causative CNVs. Future work should focus on further understanding of f-ASD genetic underpinnings, taking advantage of next-generation sequencing technologies, with the ultimate goal of contributing to precision medicine in ASD.

LIM and SH3 protein 1 localizes to the leading edge of protruding lamellipodia and regulates axon development

The actin cytoskeleton drives cell motility and is essential for neuronal development and function. LIM and SH3 protein 1 (LASP1) is a unique actin-binding protein that is expressed in a wide range of cells including neurons, but its roles in cellular motility and neuronal development are not well understood. We report that LASP1 is expressed in rat hippocampus early in development, and this expression is maintained through adulthood. High-resolution imaging reveals that LASP1 is selectively concentrated at the leading edge of lamellipodia in migrating cells and axonal growth cones. This local enrichment of LASP1 is dynamically associated with the protrusive activity of lamellipodia, depends on the barbed ends of actin filaments, and requires both the LIM domain and the nebulin repeats of LASP1. Knockdown of LASP1 in cultured rat hippocampal neurons results in a substantial reduction in axonal outgrowth and arborization. Finally, loss of the Drosophila homologue Lasp from a subset of commissural neurons in the developing ventral nerve cord produces defasciculated axon bundles that do not reach their targets. Together, our data support a novel role for LASP1 in actin-based lamellipodial protrusion and establish LASP1 as a positive regulator of both in vitro and in vivo axon development.

Genome-wide association study of emotional empathy in children

The genetic contribution to different aspects of empathy is now established, although the exact loci are unknown. We undertook a genome-wide association study of emotional empathy (EE) as measured by emotion recognition skills in 4,780 8-year old children from the ALSPAC cohort who were genotyped and imputed to Phase 1 version 3 of the 1000 Genomes Project. We failed to find any genome-wide significant signal in either our unstratified analysis or analysis stratified according to sex. A gene-based association analysis similarly failed to find any significant loci. In contrast, our transcriptome-wide association study (TWAS) with a whole blood reference panel identified two significant loci in the unstratified analysis, residualised for the effects of age, sex and IQ. One signal was for CD93 on chromosome 20; this gene is not strongly expressed in the brain, however. The other signal was for AL118508, a non-protein coding pseudogene, which completely lies within CD93’s genomic coordinates, thereby explaining its signal. Neither are obvious candidates for involvement in the brain processes that underlie emotion recognition and its developmental pathways.

The Nebulin Family LIM and SH3 Proteins Regulate Postsynaptic Development and Function

Neuronal dendrites have specialized actin-rich structures called dendritic spines that receive and integrate most excitatory synaptic inputs. The stabilization of dendrites and spines during neuronal maturation is essential for proper neural circuit formation. Changes in dendritic morphology and stability are largely mediated by regulation of the actin cytoskeleton; however, the underlying mechanisms remain to be fully elucidated. Here, we present evidence that the nebulin family members LASP1 and LASP2 play an important role in the postsynaptic development of rat hippocampal neurons from both sexes. We find that both LASP1 and LASP2 are enriched in dendritic spines, and their knockdown impairs spine development and synapse formation. Furthermore, LASP2 exerts a distinct role in dendritic arbor and dendritic spine stabilization. Importantly, the actin-binding N-terminal LIM domain and nebulin repeats of LASP2 are required for spine stability and dendritic arbor complexity. These findings identify LASP1 and LASP2 as novel regulators of neuronal circuitry.SIGNIFICANCE STATEMENT Proper regulation of the actin cytoskeleton is essential for the structural stability of dendrites and dendritic spines. Consequently, the malformation of dendritic structures accompanies numerous neurologic disorders, such as schizophrenia and autism. Nebulin family members are best known for their role in regulating the stabilization and function of actin thin filaments in muscle. The two smallest family members, LASP1 and LASP2, are more structurally diverse and are expressed in a broader array of tissues. While both LASP1 and LASP2 are highly expressed in the brain, little is currently known about their function in the nervous system. In this study, we demonstrate the first evidence that LASP1 and LASP2 are involved in the formation and long-term maintenance of dendrites and dendritic spines.

Myosin Id localizes in dendritic spines through the tail homology 1 domain

Dendritic spines, the postsynaptic compartments at excitatory synapses, are capable of changing their shape and size to modulate synaptic transmission. The actin cytoskeleton and a variety of actin-binding proteins play a critical role in the dynamics of dendritic spines. Class I myosins are monomeric motor proteins that move along actin filaments using the energy of ATP hydrolysis. Of these class I myosins, myosin Id, the mammalian homolog of Drosophila Myo31DF, has been reported to be expressed in neurons, whereas its subcellular localization in neurons remained unknown. Here, we investigated the subcellular localization of myosin Id and determined the domain responsible for it. We found that myosin Id is enriched in the F-actin-rich pseudopodia of HEK293T cells and in the dendritic spines of primary hippocampal neurons. Both deletion and substitution of the tail homology 1 (TH1) domain drastically diminishes its colocalization with F-actin. In addition, the mutant form lacking the TH1 domain is less distributed in dendritic spines than is the full-length form. Taken together, our findings reveal that myosin Id localizes in dendritic spines through the TH1 domain.

Antidepressant drug-specific prediction of depression treatment outcomes from genetic and clinical variables

Individuals with depression differ substantially in their response to treatment with antidepressants. Specific predictors explain only a small proportion of these differences. To meaningfully predict who will respond to which antidepressant, it may be necessary to combine multiple biomarkers and clinical variables. Using statistical learning on common genetic variants and clinical information in a training sample of 280 individuals randomly allocated to 12-week treatment with antidepressants escitalopram or nortriptyline, we derived models to predict remission with each antidepressant drug. We tested the reproducibility of each prediction in a validation set of 150 participants not used in model derivation. An elastic net logistic model based on eleven genetic and six clinical variables predicted remission with escitalopram in the validation dataset with area under the curve 0.77 (95%CI; 0.66-0.88; p = 0.004), explaining approximately 30% of variance in who achieves remission. A model derived from 20 genetic variables predicted remission with nortriptyline in the validation dataset with an area under the curve 0.77 (95%CI; 0.65-0.90; p < 0.001), explaining approximately 36% of variance in who achieves remission. The predictive models were antidepressant drug-specific. Validated drug-specific predictions suggest that a relatively small number of genetic and clinical variables can help select treatment between escitalopram and nortriptyline.

ASD restricted and repetitive behaviors associated at 17q21.33: genes prioritized by expression in fetal brains

Autism spectrum disorder (ASD) is a behaviorally defined condition that manifests in infancy or early childhood as deficits in communication skills and social interactions. Often, restricted and repetitive behaviors (RRBs) accompany this disorder. ASD is polygenic and genetically complex, so we hypothesized that focusing analyses on intermediate core component phenotypes, such as RRBs, can reduce genetic heterogeneity and improve statistical power. Applying this approach, we mined Caucasian genome-wide association studies (GWAS) data from two of the largest ASD family cohorts, the Autism Genetics Resource Exchange and Autism Genome Project (AGP). Of the 12 RRBs measured by the Autism Diagnostic Interview-Revised, seven were found to be significantly familial and substantially variable, and hence, were tested for genome-wide association in 3104 ASD-affected children from 2045 families. Using a stringent significance threshold (P<7.1 × 10-9), GWAS in the AGP revealed an association between 'the degree of the repetitive use of objects or interest in parts of objects' and rs2898883 (P<6.8 × 10-9), which resides within the sixth intron of PHB. To identify the candidate target genes of the associated single-nucleotide polymorphisms at that locus, we applied chromosome conformation studies in developing human brains and implicated three additional genes: SLC35B1, CALCOCO2 and DLX3. Gene expression, brain imaging and fetal brain expression quantitative trait locus studies prioritize SLC35B1 and PHB. These analyses indicate that GWAS of single heritable features of genetically complex disorders followed by chromosome conformation studies in relevant tissues can be successful in revealing novel risk genes for single core features of ASD.

Bio-collections in autism research

Autism spectrum disorder (ASD) is a group of complex neurodevelopmental disorders with diverse clinical manifestations and symptoms. In the last 10 years, there have been significant advances in understanding the genetic basis for ASD, critically supported through the establishment of ASD bio-collections and application in research. Here, we summarise a selection of major ASD bio-collections and their associated findings. Collectively, these include mapping ASD candidate genes, assessing the nature and frequency of gene mutations and their association with ASD clinical subgroups, insights into related molecular pathways such as the synapses, chromatin remodelling, transcription and ASD-related brain regions. We also briefly review emerging studies on the use of induced pluripotent stem cells (iPSCs) to potentially model ASD in culture. These provide deeper insight into ASD progression during development and could generate human cell models for drug screening. Finally, we provide perspectives concerning the utilities of ASD bio-collections and limitations, and highlight considerations in setting up a new bio-collection for ASD research.

Associations of endocrine stress-related gene polymorphisms with risk of autism spectrum disorders: Evidence from an integrated meta-analysis

Autism spectrum disorders (ASD) are related to serotonin transporter (5-HTT) and catechol-O-methyl transferase (COMT) as two most monoaminergic polymorphic variations. However, multiple studies assessing rs4680 and 5-HTTLPR variants in ASD have reported inconsistent results. Therefore, we conducted an integrated meta-analysis to combine case-control and transmission/disequilibrium test (TDT) studies to determine whether COMT and 5-HTT are associated with ASD. We searched multiple electronic databases (PubMed, EmBase and Web of Science) to identify studies assessing the rs4680 and 5-HTTLPR variants in ASD from Jan 1997 to Dec 2016. Then allelic data from case-control and TDT studies were analyzed by the Catmap package in the R software. A total of 5 studies were eligible for the meta-analysis of rs4680, including 3 case-control, 1 TDT and 1 TDT & case-control studies. Meanwhile, 22 studies of 5-HTTLPR were available, including 16 TDT, 4 case-control and 2 TDT & case-control studies. The current meta-analysis included 814 ASD cases, 741 controls and 311 families related to rs4680; 749 ASD cases, 1,118 controls and 1,861 families relevant to 5-HTTLPR were also evaluated. For rs4680, the pooled OR was 1.18 (95% CI = 0.87-1.59, P = 0.29, P_{heterogeneity}  < 0.00001). There was no significant association of rs4680 with risk of ASD between the two subgroups. For 5-HTTLPR, the pooled OR was 1.05 (95% CI = 0.92-1.20, P = 0.4652, P_{heterogeneity}  < 0.00001). Meanwhile, we found no significant risk in individual case-control or TDT studies. The above findings indicated that neither COMT rs4680 nor 5-HTT 5-HTTLPR polymorphism significantly affects ASD risk. Autism Res 2017, 10: 1722-1736. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

Our results showed no evidence of significant association of either COMT rs4680 or 5-HTT 5-HTTLPR variants with ASD, showing that these two genes may not be major susceptible genetic factors in ASD occurrence, and may have a reciprocal action with each other in combination with environmental factors. These findings further provide evidence that a single gene variant may not dictate autism occurrence, but possibly contributes to a specific phenotype or subtype of ASD.

Myosins: Domain Organisation, Motor Properties, Physiological Roles and Cellular Functions

Myosins are cytoskeletal motor proteins that use energy derived from ATP hydrolysis to generate force and movement along actin filaments. Humans express 38 myosin genes belonging to 12 classes that participate in a diverse range of crucial activities, including muscle contraction, intracellular trafficking, cell division, motility, actin cytoskeletal organisation and cell signalling. Myosin malfunction has been implicated a variety of disorders including deafness, hypertrophic cardiomyopathy, Usher syndrome, Griscelli syndrome and cancer. In this chapter, we will first discuss the key structural and kinetic features that are conserved across the myosin family. Thereafter, we summarise for each member in turn its unique functional and structural adaptations, cellular roles and associated pathologies. Finally, we address the broad therapeutic potential for pharmacological interventions that target myosin family members.

Knockdown of Unconventional Myosin ID Expression Induced Morphological Change in Oligodendrocytes

Myelin is a special multilamellar structure involved in various functions in the nervous system. In the central nervous system, the oligodendrocyte (OL) produces myelin and has a unique morphology. OLs have a dynamic membrane sorting system associated with cytoskeletal organization, which aids in the production of myelin. Recently, it was reported that the assembly and disassembly of actin filaments is crucial for myelination. However, the partner myosin molecule which associates with actin filaments during the myelination process has not yet been identified. One candidate myosin is unconventional myosin ID (Myo1d) which is distributed throughout central nervous system myelin; however, its function is still unclear. We report here that Myo1d is expressed during later stages of OL differentiation, together with myelin proteolipid protein (PLP). In addition, Myo1d is distributed at the leading edge of the myelin-like membrane in cultured OL, colocalizing mainly with actin filaments, 2',3'-cyclic nucleotide phosphodiesterase and partially with PLP. Myo1d-knockdown with specific siRNA induces significant morphological changes such as the retraction of processes and degeneration of myelin-like membrane, and finally apoptosis. Furthermore, loss of Myo1d by siRNA results in the impairment of intracellular PLP transport. Together, these results suggest that Myo1d may contribute to membrane dynamics either in wrapping or transporting of myelin membrane proteins during formation and maintenance of myelin.

Myosin-I molecular motors at a glance

Myosin-I molecular motors are proposed to play various cellular roles related to membrane dynamics and trafficking. In this Cell Science at a Glance article and the accompanying poster, we review and illustrate the proposed cellular functions of metazoan myosin-I molecular motors by examining the structural, biochemical, mechanical and cell biological evidence for their proposed molecular roles. We highlight evidence for the roles of myosin-I isoforms in regulating membrane tension and actin architecture, powering plasma membrane and organelle deformation, participating in membrane trafficking, and functioning as a tension-sensitive dock or tether. Collectively, myosin-I motors have been implicated in increasingly complex cellular phenomena, yet how a single isoform accomplishes multiple types of molecular functions is still an active area of investigation. To fully understand the underlying physiology, it is now essential to piece together different approaches of biological investigation. This article will appeal to investigators who study immunology, metabolic diseases, endosomal trafficking, cell motility, cancer and kidney disease, and to those who are interested in how cellular membranes are coupled to the underlying actin cytoskeleton in a variety of different applications.

Myosin Id is required for planar cell polarity in ciliated tracheal and ependymal epithelial cells

In wild type (WT) tracheal epithelial cells, ciliary basal bodies are oriented such that all cilia on the cell surface beat in the same upward direction. This precise alignment of basal bodies and, as a result, the ciliary axoneme, is termed rotational planar cell polarity (PCP). Rotational PCP in the multi-ciliated epithelial cells of the trachea is perturbed in rats lacking myosin Id (Myo1d). Myo1d is localized in the F-actin and basal body rich subapical cortex of the ciliated tracheal epithelial cell. Scanning and transmission electron microscopy of Myo1d knock out (KO) trachea revealed that the unidirectional bending pattern is disrupted. Instead, cilia splay out in a disordered, often radial pattern. Measurement of the alignment axis of the central pair axonemal microtubules was much more variable in the KO, another indicator that rotational PCP is perturbed. The asymmetric localization of the PCP core protein Vangl1 is lost. Both the velocity and linearity of cilia-driven movement of beads above the tracheal mucosal surface was impaired in the Myo1d KO. Multi-ciliated brain ependymal epithelial cells exhibit a second form of PCP termed translational PCP in which basal bodies and attached cilia are clustered at the anterior side of the cell. The precise asymmetric clustering of cilia is disrupted in the ependymal cells of the Myo1d KO rat. While basal body clustering is maintained, left-right positioning of the clusters is lost.

An update on the LIM and SH3 domain protein 1 (LASP1): a versatile structural, signaling, and biomarker protein

The gene encoding the LIM and SH3 domain protein (LASP1) was cloned two decades ago from a cDNA library of breast cancer metastases. As the first protein of a class comprising one N-terminal LIM and one C-terminal SH3 domain, LASP1 founded a new LIM-protein subfamily of the nebulin group. Since its discovery LASP1 proved to be an extremely versatile protein because of its exceptional structure allowing interaction with various binding partners, its ubiquitous expression in normal tissues, albeit with distinct expression patterns, and its ability to transmit signals from the cytoplasm into the nucleus. As a result, LASP1 plays key roles in cell structure, physiological processes, and cell signaling. Furthermore, LASP1 overexpression contributes to cancer aggressiveness hinting to a potential value of LASP1 as a cancer biomarker.

In this review we summarize published data on structure, regulation, function, and expression pattern of LASP1, with a focus on its role in human cancer and as a biomarker protein. In addition, we provide a comprehensive transcriptome analysis of published microarrays (n=2,780) that illustrates the expression profile of LASP1 in normal tissues and its overexpression in a broad range of human cancer entities.

The emerging picture of autism spectrum disorder: genetics and pathology

Autism spectrum disorder (ASD) is defined by impaired social interaction and communication accompanied by stereotyped behaviors and restricted interests. Although ASD is common, its genetic and clinical features are highly heterogeneous. A number of recent breakthroughs have dramatically advanced our understanding of ASD from the standpoint of human genetics and neuropathology. These studies highlight the period of fetal development and the processes of chromatin structure, synaptic function, and neuron-glial signaling. The initial efforts to systematically integrate findings of multiple levels of genomic data and studies of mouse models have yielded new clues regarding ASD pathophysiology. This early work points to an emerging convergence of disease mechanisms in this complex and etiologically heterogeneous disorder.

Nucleus to Synapse Nesprin1 Railroad Tracks Direct Synapse Maturation through RNA Localization

An important mechanism underlying synapse development and plasticity is the localization of mRNAs that travel from the nucleus to synaptic sites. Here we demonstrate that the giant nuclear-associated Nesprin1 (dNesp1) forms striated F-actin-based filaments, which we dubbed "railroad tracks," that span from muscle nuclei to postsynaptic sites at the neuromuscular junction in Drosophila. These railroad tracks specifically wrap around immature boutons formed during development and in response to electrical activity. In the absence of dNesp1, mRNAs normally localized at postsynaptic sites are lacking and synaptic maturation is inhibited. This dNesp1 function does not depend on direct association of dNesp1 isoforms with the nuclear envelope. We also show that dNesp1 functions with an unconventional myosin, Myo1D, and that both dNesp1 and Myo1D are mutually required for their localization to immature boutons. These studies unravel a novel pathway directing the transport of mRNAs from the nucleus to postsynaptic sites during synaptic maturation. VIDEO ABSTRACT.

T-Brain-1--A Potential Master Regulator in Autism Spectrum Disorders

T-Brain-1 (TBR1), a causative gene in autism spectrum disorders (ASDs), encodes a brain-specific T-box transcription factor. It is therefore possible that TBR1 controls the expression of other autism risk factors. The downstream genes of TBR1 have been identified using microarray and promoter analyses. In this study, we annotated individual genes downstream of TBR1 and investigated any associations with ASDs through extensive literature searches. Of 124 TBR1 target genes, 23 were reported to be associated with ASDs. In addition, one gene, Kiaa0319, is a known causative gene for dyslexia, a disorder frequently associated with autism. A change in expression level in 10 of these 24 genes has been previously confirmed. We further validated the alteration of RNA expression levels of Kiaa0319, Baiap2, and Gad1 in Tbr1 deficient mice. Among these 24 genes, four transcription factors Auts2, Nfia, Nr4a2, and Sox5 were found, suggesting that TBR1 controls a transcriptional cascade relevant to autism pathogenesis. A further five of the 24 genes (Cd44, Cdh8, Cntn6, Gpc6, and Ntng1) encode membrane proteins that regulate cell adhesion and axonal outgrowth. These genes likely contribute to the role of TBR1 in regulation of neuronal migration and axonal extension. Besides, decreases in Grin2b expression and increases in Gad1 expression imply that neuronal activity may be aberrant in Tbr1 deficient mice. These analyses provide direction for future experiments to reveal the pathogenic mechanism of autism.

ASIC2 subunits facilitate expression at the cell surface and confer regulation by PSD-95

Acid-sensing ion channels (ASICs) are Na⁺ channels activated by changes in pH within the peripheral and central nervous systems. Several different isoforms of ASICs combine to form trimeric channels, and their properties are determined by their subunit composition. ASIC2 subunits are widely expressed throughout the brain, where they heteromultimerize with their partnering subunit, ASIC1a. However, ASIC2 contributes little to the pH sensitivity of the channels, and so its function is not well understood. We found that ASIC2 increased cell surface levels of the channel when it is coexpressed with ASIC1a, and genetic deletion of ASIC2 reduced acid-evoked current amplitude in mouse hippocampal neurons. Additionally, ASIC2a interacted with the neuronal synaptic scaffolding protein PSD-95, and PSD-95 reduced cell surface expression and current amplitude in ASICs that contain ASIC2a. Overexpression of PSD-95 also reduced acid-evoked current amplitude in hippocampal neurons. This result was dependent upon ASIC2 since the effect of PSD-95 was abolished in ASIC2−/− neurons. These results lend support to an emerging role of ASIC2 in the targeting of ASICs to surface membranes, and allows for interaction with PSD-95 to regulate these processes.

Transcriptomic changes in the frontal cortex associated with paternal age

BACKGROUND

Advanced paternal age is robustly associated with several human neuropsychiatric disorders, particularly autism. The precise mechanism(s) mediating the paternal age effect are not known, but they are thought to involve the accumulation of de novo (epi)genomic alterations. In this study we investigate differences in the frontal cortex transcriptome in a mouse model of advanced paternal age.

FINDINGS

Transcriptomic profiling was undertaken for medial prefrontal cortex tissue dissected from the male offspring of young fathers (2 month old, 4 sires, n = 16 offspring) and old fathers (10 month old, 6 sires, n = 16 offspring) in a mouse model of advancing paternal age. We found a number of differentially expressed genes in the offspring of older fathers, many previously implicated in the aetiology of autism. Pathway analysis highlighted significant enrichment for changes in functional networks involved in inflammation and inflammatory disease, which are also implicated in autism.

CONCLUSIONS

We observed widespread alterations to the transcriptome associated with advanced paternal age with an enrichment of genes associated with inflammation, an interesting observation given previous evidence linking the immune system to several neuropsychiatric disorders including autism.

Localization and behaviors in null mice suggest that ASIC1 and ASIC2 modulate responses to aversive stimuli

Acid-sensing ion channels (ASICs) generate H(+) -gated Na(+) currents that contribute to neuronal function and animal behavior. Like ASIC1, ASIC2 subunits are expressed in the brain and multimerize with ASIC1 to influence acid-evoked currents and facilitate ASIC1 localization to dendritic spines. To better understand how ASIC2 contributes to brain function, we localized the protein and tested the behavioral consequences of ASIC2 gene disruption. For comparison, we also localized ASIC1 and studied ASIC1(-/-) mice. ASIC2 was prominently expressed in areas of high synaptic density, and with a few exceptions, ASIC1 and ASIC2 localization exhibited substantial overlap. Loss of ASIC1 or ASIC2 decreased freezing behavior in contextual and auditory cue fear conditioning assays, in response to predator odor and in response to CO2 inhalation. In addition, loss of ASIC1 or ASIC2 increased activity in a forced swim assay. These data suggest that ASIC2, like ASIC1, plays a key role in determining the defensive response to aversive stimuli. They also raise the question of whether gene variations in both ASIC1 and ASIC2 might affect fear and panic in humans.

Sex-specific association of a common variant of the XG gene with autism spectrum disorders

Autism spectrum disorders (ASD) are much more common in males than in females. Studies using both linkage and candidate gene association approaches have identified genetic variants specific to families in which all affected cases were male, suggesting that sex may interact with or otherwise influence the expression of specific genes in association with ASD. In this study, we specifically evaluated the sex-specific genetic effects of ASD with a family-based genome-wide association study approach using the data from the Autism Genetic Resource Exchange repository. We evaluated the male-specific genetic effects of ASD in 374 multiplex families of European ancestry in which all affected were male (male-only; MO) and identified a novel genome-wide significant association in the pseudoautosomal boundary on chromosome Xp22.33/Yp11.31 in the MO families of predominantly paternal origin (rs2535443, p = 3.8 × 10(-8) ). Five markers that reside within a 550 kb intergenic region on chromosome 13q33.3, between the MYO16 and IRS2 genes, also showed suggestive association with ASD in the MO families (p = 3.3 × 10(-5) to 5.3 × 10(-7) ). In contrast, none of these markers appeared to be associated with ASD in the families containing any affected females. Our results suggest that the pseudoautosomal boundary on Xp22.33/Yp11.31 may harbor male-specific genetic variants for ASD.

Acid-sensing ion channels in pain and disease

Why do neurons sense extracellular acid? In large part, this question has driven increasing investigation on acid-sensing ion channels (ASICs) in the CNS and the peripheral nervous system for the past two decades. Significant progress has been made in understanding the structure and function of ASICs at the molecular level. Studies aimed at clarifying their physiological importance have suggested roles for ASICs in pain, neurological and psychiatric disease. This Review highlights recent findings linking these channels to physiology and disease. In addition, it discusses some of the implications for therapy and points out questions that remain unanswered.

Lasp1 is down-regulated in NMDA receptor antagonist-treated mice and implicated in human schizophrenia susceptibility

Mice treated with MK-801, a non-competitive antagonist of the N-methyl-d-aspartic (NMDA) acid receptor, are important animal models for schizophrenia studies. In the present study, we compared protein expression levels in the hippocampus of mice treated with MK-801 (0.6 mg/kg) or saline once daily for 7 days. Changes in the proteome were detected by two-dimensional electrophoresis, and the six proteins exhibiting differential expression were identified by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Down-regulation of one of these proteins, Lasp1 (LIM and SH3 protein 1), in MK-801-treated mice was confirmed by western blotting and immunohistochemical analyses. Lasp1 is a multidomain protein that may recruit signaling molecules to the actin-based cytoskeleton and is known to concentrate in synaptic sites of hippocampal neurons. We next investigated whether polymorphisms in the human LASP1 gene were associated with schizophrenia in the Korean population. A single-nucleotide polymorphism in the LASP1 gene promoter region was associated with schizophrenia susceptibility. Our results suggest that LASP1 might be associated with NMDA receptor antagonism and schizophrenia susceptibility and, thus, might be involved in the pathophysiology of schizophrenia.

Allowing for sex differences increases power in a GWAS of multiplex Autism families

Current genomewide association studies account for only a small fraction of the estimated heritabilities of genetically complex neuropsychiatric disorders, indicating they are likely to result from the small effects of numerous predisposing variants, many of which have gone undetected. The statistical power to detect associations of common variants with small effects is increased by conducting joint association tests of a single nucleotide polymorphism (SNP), an additional risk factor (F), and their interaction. F can represent an environmental exposure, another genotype or any source of genetic heterogeneity. In case and control studies, logistic regression makes joint tests straightforward. This analytic method cannot be employed directly when SNP transmission tests are used to detect associations in parent/affected child trios and multiplex families. However, the method can be implemented using the case/pseudocontrol approach. We applied this approach to analyze data from a genomewide association study of multiplex families ascertained for Autism Spectrum Disorder, where sex was used to define the F. Joint analyses revealed two associations exceeding genomewide significance. One novel gene, Ryandine Receptor 2, implicated in calcium channel defects, was identified with a joint P-value of 3.9E-11. Calcium channel defects have been connected to Autism spectrum disorder (ASD) by Timothy Syndrome, which is Mendelian, and a previous targeted sex-specific association analysis of idiopathic Autism. A second gene, uridine phosphorylase 2, with a joint P-value of 2.3E-9, has been previously linked and associated with Autism in independent samples. These findings highlight two Autism candidate genes for follow-up studies.

Expression and localization of myosin-1d in the developing nervous system

Myosin-1d is a monomeric actin-based motor found in a wide range of tissues, but highly expressed in the nervous system. Previous microarray studies suggest that myosin-1d is found in oligodendrocytes where transcripts are upregulated during the maturation of these cells. Myosin-1d was also identified as a component of myelin-containing subcellular fractions in proteomic studies and mutations in MYO1D have been linked to autism. Despite the potential implications of these previous studies, there is little information on the expression and localization of myosin-1d in the developing nervous system. Therefore, we analyzed myosin-1d expression patterns in the peripheral and central nervous systems during postnatal development. In mouse sciatic nerve, myosin-1d is expressed along the axon and in the ensheathing myelin compartment. Analysis of mouse cerebellum prior to myelination at day 3 reveals that myosin-1d is present in the Purkinje cell layer, granule cell layer, and region of the cerebellar nuclei. Upon the onset of myelination, myosin-1d enrichment expands along axonal tracts, while still present in the Purkinje and granule cell layers. However, myosin-1d was undetectable in oligodendrocyte progenitor cells at early and late time points. We also show that myosin-1d interacts and is co-expressed with aspartoacylase, an enzyme that plays a key role in fatty acid synthesis throughout the nervous system. Together, these studies provide a foundation for understanding the role of myosin-1d in neurodevelopment and neurological disorders.

A genome-wide study of panic disorder suggests the amiloride-sensitive cation channel 1 as a candidate gene

Panic disorder (PD) is a mental disorder with recurrent panic attacks that occur spontaneously and are not associated to any particular object or situation. There is no consensus on what causes PD. However, it is recognized that PD is influenced by environmental factors, as well as genetic factors. Despite a significant hereditary component, genetic studies have only been modestly successful in identifying genes of importance for the development of PD. In this study, we conducted a genome-wide scan using microsatellite markers and PD patients and control individuals from the isolated population of the Faroe Islands. Subsequently, we conducted a fine mapping, which revealed the amiloride-sensitive cation channel 1 (ACCN1) located on chromosome 17q11.2-q12 as a potential candidate gene for PD. The further analyses of the ACCN1 gene using single-nucleotide polymorphisms (SNPs) revealed significant association with PD in an extended Faroese case-control sample. However, analyses of a larger independent Danish case-control sample yielded no substantial significant association. This suggests that the possible risk alleles associated in the isolated population are not those involved in the development of PD in a larger outbred population.

A sex-specific association of common variants of neuroligin genes (NLGN3 and NLGN4X) with autism spectrum disorders in a Chinese Han cohort

Background

Synaptic genes, NLGN3 and NLGN4X, two homologous members of the neuroligin family, have been supposed as predisposition loci for autism spectrum disorders (ASDs), and defects of these two genes have been identified in a small fraction of individuals with ASDs. But no such rare variant in these two genes has as yet been adequately replicated in Chinese population and no common variant has been further investigated to be associated with ASDs.

Methods

7 known ASDs-related rare variants in NLGN3 and NLGN4X genes were screened for replication of the initial findings and 12 intronic tagging single nucleotide polymorphisms (SNPs) were genotyped for case-control association analysis in a total of 229 ASDs cases and 184 control individuals in a Chinese Han cohort, using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.

Results

We found that a common intronic variant, SNP rs4844285 in NLGN3 gene, and a specific 3-marker haplotype X^A-X^G-X^T (rs11795613-rs4844285-rs4844286) containing this individual SNP were associated with ASDs and showed a male bias, even after correction for multiple testing (SNP allele: P = 0.048, haplotype:P = 0.032). Simultaneously, none of these 7 known rare mutation of NLGN3 and NLGN4X genes was identified, neither in our patients with ASDs nor controls, giving further evidence that these known rare variants might be not enriched in Chinese Han cohort.

Conclusion

The present study provides initial evidence that a common variant in NLGN3 gene may play a role in the etiology of ASDs among affected males in Chinese Han population, and further supports the hypothesis that defect of synapse might involvement in the pathophysiology of ASDs.

Copy number variants: a new molecular frontier in clinical psychiatry

Molecular genetic research, building on genetic epidemiology, has provided the field of psychiatry with a host of exciting advances. It is now clear beyond any reasonable doubt that genetic inheritance influences liability to develop almost every major psychiatric disorder. Rapid progress in identifying genes contributing to psychiatric liability, recently accelerated by the advent of approaches such as genome-wide association studies and chromosomal microarray analysis, raises a critical question for psychiatric practice and training: how will molecular genetics alter the practice of psychiatry for front-line clinicians? The premise of the present review is that our growing knowledge regarding the roles of copy number variants in behavioral disorders will soon require revision of standards of evaluation and care for psychiatric patients.

Deletion 17q12 is a recurrent copy number variant that confers high risk of autism and schizophrenia

Autism spectrum disorders (ASD) and schizophrenia are neurodevelopmental disorders for which recent evidence indicates an important etiologic role for rare copy number variants (CNVs) and suggests common genetic mechanisms. We performed cytogenomic array analysis in a discovery sample of patients with neurodevelopmental disorders referred for clinical testing. We detected a recurrent 1.4 Mb deletion at 17q12, which harbors HNF1B, the gene responsible for renal cysts and diabetes syndrome (RCAD), in 18/15,749 patients, including several with ASD, but 0/4,519 controls. We identified additional shared phenotypic features among nine patients available for clinical assessment, including macrocephaly, characteristic facial features, renal anomalies, and neurocognitive impairments. In a large follow-up sample, the same deletion was identified in 2/1,182 ASD/neurocognitive impairment and in 4/6,340 schizophrenia patients, but in 0/47,929 controls (corrected p = 7.37 × 10⁻⁵). These data demonstrate that deletion 17q12 is a recurrent, pathogenic CNV that confers a very high risk for ASD and schizophrenia and show that one or more of the 15 genes in the deleted interval is dosage sensitive and essential for normal brain development and function. In addition, the phenotypic features of patients with this CNV are consistent with a contiguous gene syndrome that extends beyond RCAD, which is caused by HNF1B mutations only.

High-density SNP association study of the 17q21 chromosomal region linked to autism identifies CACNA1G as a novel candidate gene

Chromosome 17q11-q21 is a region of the genome likely to harbor susceptibility to autism (MIM(209850)) based on earlier evidence of linkage to the disorder. This linkage is specific to multiplex pedigrees containing only male probands (MO) within the Autism Genetic Resource Exchange (AGRE). Earlier, Stone et al.(1) completed a high-density single nucleotide polymorphism association study of 13.7 Mb within this interval, but common variant association was not sufficient to account for the linkage signal. Here, we extend this single nucleotide polymorphism-based association study to complete the coverage of the two-LOD support interval around the chromosome 17q linkage peak by testing the majority of common alleles in 284 MO trios. Markers within an interval containing the gene, CACNA1G, were found to be associated with Autism Spectrum Disorder at a locally significant level (P=1.9 × 10(-5)). While establishing CACNA1G as a novel candidate gene for autism, these alleles do not contribute a sufficient genetic effect to explain the observed linkage, indicating that there is substantial genetic heterogeneity despite the clear linkage signal. The region thus likely harbors a combination of multiple common and rare alleles contributing to the genetic risk. These data, along with earlier studies of chromosomes 5 and 7q3, suggest few if any major common risk alleles account for Autism Spectrum Disorder risk under major linkage peaks in the AGRE sample. This provides important evidence for strategies to identify Autism Spectrum Disorder genes, suggesting that they should focus on identifying rare variants and common variants of small effect.

Genome-wide haplotype association analysis and gene prioritization identify CCL3 as a risk locus for rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease caused by a complex interaction of multiple genetic variants and environmental factors. The association between RA and genetic susceptibility loci has been observed in many different populations, and most studies have focused on univariate analyses of single nucleotide polymorphisms. We performed a genome-wide haplotype association study and prioritized RA-related genes within 100 kb in either direction of significant haplotypes (P < 0.0001), based on their similarity to known RA susceptibility genes. The results showed that the chemokine CCL3 was associated with susceptibility to RA. A haplotype that located CCL3 on chromosome 17q12 had significant correlation with RA (P = 7.56E-05), and the global similarity score of CCL3 was ranked in the top of all RA-related genes, excluding known susceptibility genes (P = 8.42E-07). Our findings provide further evidence for the potential importance of the chemokine CCL3 in RA, and will facilitate the further understanding of its role in immunological regulation and the pathogenesis of RA.

A genomewide association study of citalopram response in major depressive disorder

BACKGROUND

Antidepressant response is likely influenced by genetic constitution, but the actual genes involved have yet to be determined. We have carried out a genomewide association study to determine whether common DNA variation influences antidepressant response.

METHODS

Our sample is derived from Level 1 participants in the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study, all treated with citalopram. Association for the response phenotype included 883 responders and 608 nonresponders. For the remission phenotype, 743 subjects that achieved remission were compared with 608 nonresponders. We used a subset of single nucleotide polymorphisms (SNPs; n = 430,198) from the Affymetrix 500K and 5.0 Human SNP Arrays, and association analysis was carried out after correcting for population stratification.

RESULTS

We identified three SNPs associated with response with p values less than 1 x 10(-5) near the UBE3C gene (rs6966038, p = 4.65 x 10(-7)), another 100 kb away from BMP7 (rs6127921, p = 3.45 x 10(-6)), and a third that is intronic in the RORA gene (rs809736, p = 8.19 x 10(-6)). These same SNPs were also associated with remission. Thirty-nine additional SNPs are of interest with p values < or = .0001 for the response and remission phenotypes.

CONCLUSIONS

Although the findings reported here do not meet a genomewide threshold for significance, the regions identified from this study provide targets for independent replication and novel pathways to investigate mechanisms of antidepressant response. This study was not placebo controlled, making it possible that we are also observing associations to nonspecific aspects of drug treatment of depression.

ASIC2 subunits target acid-sensing ion channels to the synapse via an association with PSD-95

Acid-sensing ion channel-1a (ASIC1a) mediates H(+)-gated current to influence normal brain physiology and impact several models of disease. Although ASIC2 subunits are widely expressed in brain and modulate ASIC1a current, their function remains poorly understood. We identified ASIC2a in dendrites, dendritic spines, and brain synaptosomes. This localization largely relied on ASIC2a binding to PSD-95 and matched that of ASIC1a, which does not coimmunoprecipitate with PSD-95. We found that ASIC2 and ASIC1a associated in brain, and through its interaction with PSD-95, ASIC2 increased ASIC1a localization in dendritic spines. Consistent with earlier work showing that acidic pH elevated spine [Ca(2+)](i) by activating ASIC1a, loss of ASIC2 decreased the percentage of spines responding to acid. Moreover, like a reduction of ASIC1a, the number of spine synapses fell in ASIC2(-/-) neurons. These results indicate that ASIC2 facilitates ASIC1a localization and function in dendritic spines and suggest that the two subunits work in concert to regulate neuronal function.

Gene expression profiling differentiates autism case-controls and phenotypic variants of autism spectrum disorders: evidence for circadian rhythm dysfunction in severe autism

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by delayed/abnormal language development, deficits in social interaction, repetitive behaviors and restricted interests. The heterogeneity in clinical presentation of ASD, likely due to different etiologies, complicates genetic/biological analyses of these disorders. DNA microarray analyses were conducted on 116 lymphoblastoid cell lines (LCL) from individuals with idiopathic autism who are divided into three phenotypic subgroups according to severity scores from the commonly used Autism Diagnostic Interview-Revised questionnaire and age-matched, nonautistic controls. Statistical analyses of gene expression data from control LCL against that of LCL from ASD probands identify genes for which expression levels are either quantitatively or qualitatively associated with phenotypic severity. Comparison of the significant differentially expressed genes from each subgroup relative to the control group reveals differentially expressed genes unique to each subgroup as well as genes in common across subgroups. Among the findings unique to the most severely affected ASD group are 15 genes that regulate circadian rhythm, which has been shown to have multiple effects on neurological as well as metabolic functions commonly dysregulated in autism. Among the genes common to all three subgroups of ASD are 20 novel genes mostly in putative noncoding regions, which appear to associate with androgen sensitivity and which may underlie the strong 4:1 bias toward affected males.

Molecular genetics of autism

The increasing autism incidence estimates are generating strong interest in identifying its salient risk factors. Recognition of the importance of genes in this and other disorders has promulgated the development of valuable research tools. As this review indicates, application of these tools paints a portrait of a disorder that is more complex than anticipated.

Genome-wide association study to identify novel loci associated with therapy-related myeloid leukemia susceptibility

Therapy-related acute myeloid leukemia (t-AML) is a rare but fatal complication of cytotoxic therapy. Whereas sporadic cancer results from interactions between complex exposures and low-penetrance alleles, t-AML results from an acute exposure to a limited number of potent genotoxins. Consequently, we hypothesized that the effect sizes of variants associated with t-AML would be greater than in sporadic cancer, and, therefore, that these variants could be detected even in a modest-sized cohort. To test this, we undertook an association study in 80 cases and 150 controls using Affymetrix Mapping 10K arrays. Even at nominal significance thresholds, we found a significant excess of associations over chance; for example, although 6 associations were expected at P less than .001, we found 15 (P(enrich) = .002). To replicate our findings, we genotyped the 10 most significantly associated single nucleotide polymorphisms (SNPs) in an independent t-AML cohort (n = 70) and obtained evidence of association with t-AML for 3 SNPs in the subset of patients with loss of chromosomes 5 or 7 or both, acquired abnormalities associated with prior exposure to alkylator chemotherapy. Thus, we conclude that the effect of genetic factors contributing to cancer risk is potentiated and more readily discernable in t-AML compared with sporadic cancer.

A review of recent reports on autism: 1000 studies published in 2007

From 1000 studies published in 2007 on all aspects of autism, those that reached clear conclusions or included quantitative data were selected for this review. Possible etiologies include elemental metals, especially the inconsistent evidence regarding mercury from the vaccine preservative thimerosal, not used after 2001, and chromosomes and genes with the conclusion that autism has a complex genetic architecture. Also, various parental conditions are considered, as are many different abnormalities in the central nervous system, especially underconnectivity within the cortex. Furthermore, deficiencies in mirror neurons have been proposed, leading to the "theory of mind" explanation that autistic children tend to disregard others. In addition, various global deficiencies, like an increase in inhibitory synaptic transmission, are proposed. Characteristics of these children include selective (inward) attention; underresponsiveness; stereotyped repetitive motor behavior; increased head size, weight, and height; various cognitive and communicative disorders; and also epilepsy. Therapy has emphasized risperidone, but some atypical antipsychotic medications have been helpful, as have robotic aids, massage, hyperbaric oxygen, and music. Nearly every conceivable problem that a child could have can be observed in these unfortunate children.

Advances in autism genetics: on the threshold of a new neurobiology

Autism is a heterogeneous syndrome defined by impairments in three core domains: social interaction, language and range of interests. Recent work has led to the identification of several autism susceptibility genes and an increased appreciation of the contribution of de novo and inherited copy number variation. Promising strategies are also being applied to identify common genetic risk variants. Systems biology approaches, including array-based expression profiling, are poised to provide additional insights into this group of disorders, in which heterogeneity, both genetic and phenotypic, is emerging as a dominant theme.

The LIM and SH3 domain protein family: structural proteins or signal transducers or both?

LIM and SH3 Protein 1 (LASP-1) was initially identified from a cDNA library of metastatic axillary lymph nodes (MLN) more than a decade ago. It was found to be overexpressed in human breast and ovarian cancer and became the first member of a newly defined LIM-protein subfamily of the nebulin group characterized by the combined presence of LIM and SH3 domains. LASP2, a novel LASP1-related gene was first identified and characterized in silico. Subsequently it proved to be a splice variant of the Nebulin gene and therefore was also termed LIM/nebulette. LASP-1 and -2 are highly conserved in their LIM, nebulin-like and SH3 domains but differ significantly at their linker regions. Both proteins are ubiquitously expressed and involved in cytoskeletal architecture, especially in the organization of focal adhesions. Here we present the first systematic review to summarize all relevant data concerning their domain organization, expression profiles, regulating factors and function. We compile evidence that both, LASP-1 and LASP-2, are important during early embryo- and fetogenesis and are highly expressed in the central nervous system of the adult. However, only LASP-1 seems to participate significantly in neuronal differentiation and plays an important functional role in migration and proliferation of certain cancer cells while the role of LASP-2 is more structural. The increased expression of LASP-1 in breast tumours correlates with high rates of nodal-metastasis and refers to a possible relevance as a prognostic marker.