Animal and Cellular Models of Alzheimer's Disease.

Animal and cellular models have been essential tools over the years to understand many pathogenic mechanisms underlying different neurodegenerative disorders (NDDs), including Alzheimer's disease (AD) [...].

Genetically Engineered Triple MAPT-Mutant Human-Induced Pluripotent Stem Cells (N279K, P301L, and E10+16 Mutations) Exhibit Impairments in Mitochondrial Bioenergetics and Dynamics.

Pathological abnormalities in the tau protein give rise to a variety of neurodegenerative diseases, conjointly termed tauopathies. Several tau mutations have been identified in the tau-encoding gene MAPT, affecting either the physical properties of tau or resulting in altered tau splicing. At early disease stages, mitochondrial dysfunction was highlighted with mutant tau compromising almost every aspect of mitochondrial function. Additionally, mitochondria have emerged as fundamental regulators of stem cell function. Here, we show that compared to the isogenic wild-type triple MAPT-mutant human-induced pluripotent stem cells, bearing the pathogenic N279K, P301L, and E10+16 mutations, exhibit deficits in mitochondrial bioenergetics and present altered parameters linked to the metabolic regulation of mitochondria. Moreover, we demonstrate that the triple tau mutations disturb the cellular redox homeostasis and modify the mitochondrial network morphology and distribution. This study provides the first characterization of disease-associated tau-mediated mitochondrial impairments in an advanced human cellular tau pathology model at early disease stages, ranging from mitochondrial bioenergetics to dynamics. Consequently, comprehending better the influence of dysfunctional mitochondria on the development and differentiation of stem cells and their contribution to disease progression may thus assist in the potential prevention and treatment of tau-related neurodegeneration.

Development and validation of the help-seeking intention scale in university students with hazardous and harmful consumption of alcohol.

Introduction: The Theory of Planned Behavior (TPB) has been proposed as suitable to study help-seeking intentions. This paper aims to develop the IH-RHAC scale (Help-seeking intention in young adults with hazardous and harmful alcohol consumption) with the TPB. The objectives of the study were: (a) to analyze the structure, reliability, and validity of the instrument, (b) to identify whether attitude, subjective norm, self-efficacy, and past help-seeking would predict help-seeking intention, and (c) to assess concurrent validity. Methods: From a total of 2,011 students who responded to the surveys, the sample was made up of 263 university students aged 18 to 29 with hazardous and harmful alcohol consumption practices, who responded to an online questionnaire including the AUDIT, IH-RHAC, and a scale of barriers and resources for alcohol consumption. Partial least squares structural equations (PLS-SEM) were used to test the hypotheses about reliability, validity of the scales, and prediction of the constructs: attitude, subjective norms, self-efficacy, and help-seeking in the past about intention. Pearson's correlations were used to obtain evidence of concurrent validity. Results: The results displayed favorable psychometric characteristics. The internal measurement model showed that attitude, self-efficacy, and prior help-seeking predicted a 27% help-seeking variance. Subjective norm did not predict intention. Discussion: It has been concluded that this is an instrument with psychometric support that can contribute to designing and/or evaluating interventions that promote the students' search for help.

Monocyte-derived cells invade brain parenchyma and amyloid plaques in human Alzheimer's disease hippocampus.

Microglia are brain-resident myeloid cells and play a major role in the innate immune responses of the CNS and the pathogenesis of Alzheimer's disease (AD). However, the contribution of nonparenchymal or brain-infiltrated myeloid cells to disease progression remains to be demonstrated. Here, we show that monocyte-derived cells (MDC) invade brain parenchyma in advanced stages of AD continuum using transcriptional analysis and immunohistochemical characterization in post-mortem human hippocampus. Our findings demonstrated that a high proportion (60%) of demented Braak V-VI individuals was associated with up-regulation of genes rarely expressed by microglial cells and abundant in monocytes, among which stands the membrane-bound scavenger receptor for haptoglobin/hemoglobin complexes or Cd163. These Cd163-positive MDC invaded the hippocampal parenchyma, acquired a microglial-like morphology, and were located in close proximity to blood vessels. Moreover, and most interesting, these invading monocytes infiltrated the nearby amyloid plaques contributing to plaque-associated myeloid cell heterogeneity. However, in aged-matched control individuals with hippocampal amyloid pathology, no signs of MDC brain infiltration or plaque invasion were found. The previously reported microglial degeneration/dysfunction in AD hippocampus could be a key pathological factor inducing MDC recruitment. Our data suggest a clear association between MDC infiltration and endothelial activation which in turn may contribute to damage of the blood brain barrier integrity. The recruitment of monocytes could be a consequence rather than the cause of the severity of the disease. Whether monocyte infiltration is beneficial or detrimental to AD pathology remains to be fully elucidated. These findings open the opportunity to design targeted therapies, not only for microglia but also for the peripheral immune cell population to modulate amyloid pathology and provide a better understanding of the immunological mechanisms underlying the progression of AD.

Transgenic Mouse Models of Alzheimer's Disease: An Integrative Analysis.

Alzheimer's disease (AD) constitutes the most prominent form of dementia among elderly individuals worldwide. Disease modeling using murine transgenic mice was first initiated thanks to the discovery of heritable mutations in amyloid precursor protein (APP) and presenilins (PS) genes. However, due to the repeated failure of translational applications from animal models to human patients, along with the recent advances in genetic susceptibility and our current understanding on disease biology, these models have evolved over time in an attempt to better reproduce the complexity of this devastating disease and improve their applicability. In this review, we provide a comprehensive overview about the major pathological elements of human AD (plaques, tauopathy, synaptic damage, neuronal death, neuroinflammation and glial dysfunction), discussing the knowledge that available mouse models have provided about the mechanisms underlying human disease. Moreover, we highlight the pros and cons of current models, and the revolution offered by the concomitant use of transgenic mice and omics technologies that may lead to a more rapid improvement of the present modeling battery.

Animal and Cellular Models of Alzheimer's Disease: Progress, Promise, and Future Approaches.

Alzheimer's disease (AD) is an incurable neurodegenerative disease affecting over 45 million people worldwide. Transgenic mouse models have made remarkable contributions toward clarifying the pathophysiological mechanisms behind the clinical manifestations of AD. However, the limited ability of these in vivo models to accurately replicate the biology of the human disease have precluded the translation of promising preclinical therapies to the clinic. In this review, we highlight several major pathogenic mechanisms of AD that were discovered using transgenic mouse models. Moreover, we discuss the shortcomings of current animal models and the need to develop reliable models for the sporadic form of the disease, which accounts for the majority of AD cases, as well as human cellular models to improve success in translating results into human treatments.

Generation of a humanized Aß expressing mouse demonstrating aspects of Alzheimer's disease-like pathology.

The majority of Alzheimer's disease (AD) cases are late-onset and occur sporadically, however most mouse models of the disease harbor pathogenic mutations, rendering them better representations of familial autosomal-dominant forms of the disease. Here, we generated knock-in mice that express wildtype human Aß under control of the mouse App locus. Remarkably, changing 3 amino acids in the mouse Aß sequence to its wild-type human counterpart leads to age-dependent impairments in cognition and synaptic plasticity, brain volumetric changes, inflammatory alterations, the appearance of Periodic Acid-Schiff (PAS) granules and changes in gene expression. In addition, when exon 14 encoding the Aß sequence was flanked by loxP sites we show that Cre-mediated excision of exon 14 ablates hAß expression, rescues cognition and reduces the formation of PAS granules.

Generation of oligodendrocytes and establishment of an all-human myelinating platform from human pluripotent stem cells.

Oligodendrocytes (OLs) are responsible for myelin production and metabolic support of neurons. Defects in OLs are crucial in several neurodegenerative diseases including multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). This protocol describes a method to generate oligodendrocyte precursor cells (OPCs) from human pluripotent stem cells (hPSCs) in only ~20 d, which can subsequently myelinate neurons, both in vitro and in vivo. To date, OPCs have been derived from eight different hPSC lines including those derived from patients with spontaneous and familial forms of MS and ALS, respectively. hPSCs, fated for 8 d toward neural progenitors, are transduced with an inducible lentiviral vector encoding for SOX10. The addition of doxycycline for 10 d results in >60% of cells being O4-expressing OPCs, of which 20% co-express the mature OL marker myelin basic protein (MBP). The protocol also describes an alternative for viral transduction, by incorporating an inducible SOX10 in the safe harbor locus AAVS1, yielding ~100% pure OPCs. O4+ OPCs can be purified and either cryopreserved or used for functional studies. As an example of the type of functional study for which the derived cells could be used, O4+ cells can be co-cultured with maturing hPSC-derived neurons in 96/384-well-format plates, allowing the screening of pro-myelinating compounds.

Human Pluripotent Stem Cell-Derived Neural Cells as a Relevant Platform for Drug Screening in Alzheimer's Disease.

Extracellular amyloid-beta deposition and intraneuronal Tau-laden neurofibrillary tangles are prime features of Alzheimer's disease (AD). The pathology of AD is very complex and still not fully understood, since different neural cell types are involved in the disease. Although neuronal function is clearly deteriorated in AD patients, recently, an increasing number of evidences have pointed towards glial cell dysfunction as one of the main causative phenomena implicated in AD pathogenesis. The complex disease pathology together with the lack of reliable disease models have precluded the development of effective therapies able to counteract disease progression. The discovery and implementation of human pluripotent stem cell technology represents an important opportunity in this field, as this system allows the generation of patient-derived cells to be used for disease modeling and therapeutic target identification and as a platform to be employed in drug discovery programs. In this review, we discuss the current studies using human pluripotent stem cells focused on AD, providing convincing evidences that this system is an excellent opportunity to advance in the comprehension of AD pathology, which will be translated to the development of the still missing effective therapies.

Toxic Nightlife Relationships, Substance Abuse, and Mental Health: Is There a Link? A Qualitative Case Study of Two Patients.

Introduction and Aims: This article explores the role of toxic close relationships in night life on substance use disorders and mental health conditions. We also contrast the quality and effects of social relationships when doing drugs with those produced by a mental health program that fosters quality relationships between patients. Design and Methods: This qualitative case study was carried out at a mental health day care center of a hospital in Malaga (Spain). The cases of two patients with severe mental disorders and a history of drug addiction were analyzed. Data were collected through in-depth interviews with every patient, semi-structured interviews about each patient with the psychologist of the medical team of the program, and medical documentation. The analysis involved a combination of inductive and deductive approaches. Results: The analysis of the data revealed, on the one hand, the influence of toxic relationships in nightlife, including violent sporadic sexual relationships, in the initiation and persistence of substance use that took part of the mental health disorder in these patients. On the other hand, the findings show that these participants' current involvement in a mental health program, which fosters quality relationships between patients, has brought emotional benefits to both of them. Discussion and Conclusion: This paper points out the relevance of considering quality of social relationships when examining substance use disorders and related mental health problems. Additionally, the findings indicate the importance of fostering quality peer relationships in mental health rehabilitation programs addressed to patients with histories of drug addiction to improve treatment outcome.

Distinct disease-sensitive GABAergic neurons in the perirhinal cortex of Alzheimer's mice and patients.

Neuronal loss is the best neuropathological substrate that correlates with cortical atrophy and dementia in Alzheimer's disease (AD). Defective GABAergic neuronal functions may lead to cortical network hyperactivity and aberrant neuronal oscillations and in consequence, generate a detrimental alteration in memory processes. In this study, using immunohistochemical and stereological approaches, we report that the two major and non-overlapping groups of inhibitory interneurons (SOM-cells and PV-cells) displayed distinct vulnerability in the perirhinal cortex of APP/PS1 mice and AD patients. SOM-positive neurons were notably sensitive and exhibited a dramatic decrease in the perirhinal cortex of 6-month-old transgenic mice (57% and 61% in areas 36 and 35, respectively) and, most importantly, in AD patients (91% in Braak V-VI cases). In addition, this interneuron degenerative process seems to occur in parallel, and closely related, with the progression of the amyloid pathology. However, the population expressing PV was unaffected in APP/PS1 mice while in AD brains suffered a pronounced and significant loss (69%). As a key component of cortico-hippocampal networks, the perirhinal cortex plays an important role in memory processes, especially in familiarity-based memory recognition. Therefore, disrupted functional connectivity of this cortical region, as a result of the early SOM and PV neurodegeneration, might contribute to the altered brain rhythms and cognitive failures observed in the initial clinical phase of AD patients. Finally, these findings highlight the failure of amyloidogenic AD models to fully recapitulate the selective neuronal degeneration occurring in humans.

Use of human pluripotent stem cell-derived cells for neurodegenerative disease modeling and drug screening platform.

Most neurodegenerative diseases are characterized by a complex and mostly still unresolved pathology. This fact, together with the lack of reliable disease models, has precluded the development of effective therapies counteracting the disease progression. The advent of human pluripotent stem cells has revolutionized the field allowing the generation of disease-relevant neural cell types that can be used for disease modeling, drug screening and, possibly, cell transplantation purposes. In this Review, we discuss the applications of human pluripotent stem cells, the development of efficient protocols for the derivation of the different neural cells and their applicability for robust in vitro disease modeling and drug screening platforms for most common neurodegenerative conditions.

Effects of exercise on the cognition of older women treated with lovastatin / Efectos del ejercicio físico sobre la cognición en mujeres mayores tratadas con lovastatina

Introduction: The deterioration of cognition is highly predominant in older adults. Objective: The aim of this study was to analyze the effects of a walking program on the cognition and blood concentration of lipids in women over 60 years of age who were being treated with lovastatin. Materials and methods: Participants were distributed in two groups: An exercise group (EG, n=45) with aerobic training and an inactive sedentary group (SG, n=22). The cognitive state of the subjects was assessed through the Spanish Mini-Cog Test version of the MMSE; lipoproteins were quantified using a lipid profile test, and the cardiorespiratory fitness was measured using the six-minute walking test (6MWT). Results: EG showed a significant increase (p<0.05) in cardiorespiratory fitness and in HDL-C concentrations. Furthermore, the results from the cognition tests showed a large effect size in spatial orientation and in and calculation. The decrease in LDL-C was not significant (p>0.05). Conclusion: A controlled and progressive walking program for older women treated with Lovastatin may induce a boost of brain activity linked to HDL-C, which could delay cognitive impairment.

Introducción. El deterioro cognitivo tiene una gran incidencia en el adulto mayor. Objetivo. El principal objetivo de este estudio fue analizar los efectos sobre la cognición y la concentración de lípidos de un programa de caminatas en mujeres mayores de 60 años tratadas con lovastatina. Materiales y métodos. Las participantes se distribuyeron en dos grupos: uno con ejercicio (EG, n=45) sometido a entrenamiento aeróbico y otro inactivo o sedentario (SG, n=22). El estado cognitivo se evaluó mediante la versión en español del Mini-Mental Test. Los niveles de lipoproteínas se midieron con una prueba de perfil lipídico y la aptitud cardiorrespiratoria se valoró con la prueba de caminata de 6 minutos (Six-Minute Walking Test, 6MWT). Resultados. El grupo con ejercicio mostró una mejora significativa (p<0,05) de la aptitud cardiorrespiratoria y de las concentraciones de colesterol HDL. Además, en la prueba de cognición se observó un efecto de gran tamaño en la orientación espacial, en la atención y en el cálculo. La reducción del colesterol LDL no fue significativa. Conclusión. Un programa de entrenamiento progresivo y supervisado para mujeres mayores tratadas con lovastatina, podría mejorar la actividad cerebral relacionada con el colesterol HDL, lo cual podría retrasar el deterioro cognitivo.

Generation of a human induced pluripotent stem cell-based model for tauopathies combining three microtubule-associated protein TAU mutations which displays several phenotypes linked to neurodegeneration.

INTRODUCTION: Tauopathies are neurodegenerative diseases characterized by TAU protein-related pathology, including frontotemporal dementia and Alzheimer's disease among others. Mutant TAU animal models are available, but none of them faithfully recapitulates human pathology and are not suitable for drug screening. METHODS: To create a new in vitro tauopathy model, we generated a footprint-free triple MAPT-mutant human induced pluripotent stem cell line (N279K, P301L, and E10+16 mutations) using clustered regularly interspaced short palindromic repeats-FokI and piggyBac transposase technology. RESULTS: Mutant neurons expressed pathogenic 4R and phosphorylated TAU, endogenously triggered TAU aggregation, and had increased electrophysiological activity. TAU-mutant cells presented deficiencies in neurite outgrowth, aberrant sequence of differentiation to cortical neurons, and a significant activation of stress response pathways. RNA sequencing confirmed stress activation, demonstrated a shift toward GABAergic identity, and an upregulation of neurodegenerative pathways. DISCUSSION: In summary, we generated a novel in vitro human induced pluripotent stem cell TAU-mutant model displaying neurodegenerative disease phenotypes that could be used for disease modeling and drug screening.

SOX10 Single Transcription Factor-Based Fast and Efficient Generation of Oligodendrocytes from Human Pluripotent Stem Cells.

Scarce access to primary samples and lack of efficient protocols to generate oligodendrocytes (OLs) from human pluripotent stem cells (hPSCs) are hampering our understanding of OL biology and the development of novel therapies. Here, we demonstrate that overexpression of the transcription factor SOX10 is sufficient to generate surface antigen O4-positive (O4+) and myelin basic protein-positive OLs from hPSCs in only 22 days, including from patients with multiple sclerosis or amyotrophic lateral sclerosis. The SOX10-induced O4+ population resembles primary human OLs at the transcriptome level and can myelinate neurons in vivo. Using in vitro OL-neuron co-cultures, myelination of neurons by OLs can also be demonstrated, which can be adapted to a high-throughput screening format to test the response of pro-myelinating drugs. In conclusion, we provide an approach to generate OLs in a very rapid and efficient manner, which can be used for disease modeling, drug discovery efforts, and potentially for therapeutic OL transplantation.

[Effects of exercise on the cognition of older women treated with lovastatin]. / Efectos del ejercicio físico sobre la cognición en mujeres mayores tratadas con lovastatina

INTRODUCTION: The deterioration of cognition is highly predominant in older adults. OBJECTIVE: The aim of this study was to analyze the effects of a walking program on the cognition and blood concentration of lipids in women over 60 years of age who were being treated with lovastatin. MATERIALS AND METHODS: Participants were distributed in two groups: An exercise group (EG, n=45) with aerobic training and an inactive sedentary group (SG, n=22). The cognitive state of the subjects was assessed through the Spanish Mini-Cog Test version of the MMSE; lipoproteins were quantified using a lipid profile test, and the cardiorespiratory fitness was measured using the six-minute walking test (6MWT). RESULTS: EG showed a significant increase (p<0.05) in cardiorespiratory fitness and in HDL-C concentrations. Furthermore, the results from the cognition tests showed a large effect size in spatial orientation and in and calculation. The decrease in LDL-C was not significant (p>0.05). CONCLUSION: A controlled and progressive walking program for older women treated with Lovastatin may induce a boost of brain activity linked to HDL-C, which could delay cognitive impairment.

Introducción. El deterioro cognitivo tiene una gran incidencia en el adulto mayor. Objetivo. El principal objetivo de este estudio fue analizar los efectos sobre la cognición y la concentración de lípidos de un programa de caminatas en mujeres mayores de 60 años tratadas con lovastatina. Materiales y métodos. Las participantes se distribuyeron en dos grupos: uno con ejercicio (EG, n=45) sometido a entrenamiento aeróbico y otro inactivo o sedentario (SG, n=22). El estado cognitivo se evaluó mediante la versión en español del Mini-Mental Test. Los niveles de lipoproteínas se midieron con una prueba de perfil lipídico y la aptitud cardiorrespiratoria se valoró con la prueba de caminata de 6 minutos (Six-Minute Walking Test, 6MWT). Resultados. El grupo con ejercicio mostró una mejora significativa (p<0,05) de la aptitud cardiorrespiratoria y de las concentraciones de colesterol HDL. Además, en la prueba de cognición se observó un efecto de gran tamaño en la orientación espacial, en la atención y en el cálculo. La reducción del colesterol LDL no fue significativa. Conclusión. Un programa de entrenamiento progresivo y supervisado para mujeres mayores tratadas con lovastatina, podría mejorar la actividad cerebral relacionada con el colesterol HDL, lo cual podría retrasar el deterioro cognitivo.

Feature Selection Applying Statistical and Neurofuzzy Methods to EEG-Based BCI.

This paper presents an investigation aimed at drastically reducing the processing burden required by motor imagery brain-computer interface (BCI) systems based on electroencephalography (EEG). In this research, the focus has moved from the channel to the feature paradigm, and a 96% reduction of the number of features required in the process has been achieved maintaining and even improving the classification success rate. This way, it is possible to build cheaper, quicker, and more portable BCI systems. The data set used was provided within the framework of BCI Competition III, which allows it to compare the presented results with the classification accuracy achieved in the contest. Furthermore, a new three-step methodology has been developed which includes a feature discriminant character calculation stage; a score, order, and selection phase; and a final feature selection step. For the first stage, both statistics method and fuzzy criteria are used. The fuzzy criteria are based on the S-dFasArt classification algorithm which has shown excellent performance in previous papers undertaking the BCI multiclass motor imagery problem. The score, order, and selection stage is used to sort the features according to their discriminant nature. Finally, both order selection and Group Method Data Handling (GMDH) approaches are used to choose the most discriminant ones.

Authentic leadership, group cohesion and group identification in security and emergency teams / Liderazgo auténtico, cohesión e identifi cación grupal en equipos de seguridad y emergencia

BACKGROUND: Authentic leadership (AL) is a kind of leadership that inspires and promotes positive psychological capacities, underlining the moral and ethical component of behavior. The proposed investigation studies the relations among AL, cohesion, and group identification in security and emergency teams. METHOD: A cross-sectional research design was conducted in which participated 221 members from 26 fire departments and operative teams from the local police of three Spanish provinces. The following questionnaires were administered: Authentic Leadership (ALQ), Group Cohesion (GEQ), and Mael and Ashford's Group Identification Questionnaire. RESULTS: A direct and positive relation was found between AL, cohesion, and group identification. An indirect relation was also found between AL and group cohesion through group identification, indicating the existence of partial mediation. CONCLUSIONS: The utility of the proposed model based on AL is considered; this model can be employed by those in charge of the fire departments and operative groups in organizations to improve workteams' cohesion. Both AL and group identification help to explain group cohesion in organizations committed to security and emergencies

ANTECEDENTES: el liderazgo auténtico (LA) es un tipo de liderazgo que inspira y promueve capacidades psicológicas positivas, destacando el componente moral y ético de las conductas. La investigación planteada estudia las relaciones entre LA, cohesión e identificación grupal en equipos de seguridad y emergencia. MÉTODO: se desarrolla un diseño de investigación transversal en el que participan 221 componentes de 26 brigadas de bomberos y equipos operativos de policía local de tres provincias españolas. Se administraron los cuestionarios ALQ de liderazgo auténtico, GEQ de cohesión grupal y el cuestionario de Mael y Ashford que mide identificación grupal. RESULTADOS: se encontró una relación directa positiva entre el LA, la cohesión y la identificación grupal. Asimismo, se encontró también una relación indirecta entre el LA y la cohesión grupal a través de la identificación grupal apuntando los datos a la existencia de una mediación parcial. CONCLUSIONES: se considera de utilidad el modelo propuesto basado en el LA, pudiendo ser empleado por los responsables de las brigadas y grupos operativos en organizaciones para mejorar la cohesión de los equipos de trabajo. Tanto el LA como la identificación grupal ayudan a explicar la cohesión grupal en organizaciones con cometidos relacionados con la seguridad y las emergencias

Authentic leadership, group cohesion and group identification in security and emergency teams.

BACKGROUND: Authentic leadership (AL) is a kind of leadership that inspires and promotes positive psychological capacities, underlining the moral and ethical component of behavior. The proposed investigation studies the relations among AL, cohesion, and group identification in security and emergency teams. METHOD: A cross-sectional research design was conducted in which participated 221 members from 26 fire departments and operative teams from the local police of three Spanish provinces. The following questionnaires were administered: Authentic Leadership (ALQ), Group Cohesion (GEQ), and Mael and Ashford's Group Identification Questionnaire. RESULTS: A direct and positive relation was found between AL, cohesion, and group identification. An indirect relation was also found between AL and group cohesion through group identification, indicating the existence of partial mediation. CONCLUSIONS: The utility of the proposed model based on AL is considered; this model can be employed by those in charge of the fire departments and operative groups in organizations to improve workteams' cohesion. Both AL and group identification help to explain group cohesion in organizations committed to security and emergencies.

Identification of a functional variant in the KIF5A-CYP27B1-METTL1-FAM119B locus associated with multiple sclerosis.

BACKGROUND AND AIM: Several studies have highlighted the association of the 12q13.3-12q14.1 region with coeliac disease, type 1 diabetes, rheumatoid arthritis and multiple sclerosis (MS); however, the causal variants underlying diseases are still unclear. The authors sought to identify the functional variant of this region associated with MS. METHODS: Tag-single nucleotide polymorphism (SNP) analysis of the associated region encoding 15 genes was performed in 2876 MS patients and 2910 healthy Caucasian controls together with expression regulation analyses. RESULTS: rs6581155, which tagged 18 variants within a region where 9 genes map, was sufficient to model the association. This SNP was in total linkage disequilibrium (LD) with other polymorphisms that associated with the expression levels of FAM119B, AVIL, TSFM, TSPAN31 and CYP27B1 genes in different expression quantitative trait loci studies. Functional annotations from Encyclopedia of DNA Elements (ENCODE) showed that six out of these rs6581155-tagged-SNPs were located in regions with regulatory potential and only one of them, rs10877013, exhibited allele-dependent (ratio A/G=9.5-fold) and orientation-dependent (forward/reverse=2.7-fold) enhancer activity as determined by luciferase reporter assays. This enhancer is located in a region where a long-range chromatin interaction among the promoters and promoter-enhancer of several genes has been described, possibly affecting their expression simultaneously. CONCLUSIONS: This study determines a functional variant which alters the enhancer activity of a regulatory element in the locus affecting the expression of several genes and explains the association of the 12q13.3-12q14.1 region with MS.