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The first genome‐wide association study in the Argentinian and Chilean populations identifies shared genetics with Europeans in Alzheimer's disease

2023 , Maria Carolina Dalmasso , Itziar de Rojas , Natividad Olivar , Carolina Muchnik , Bárbara Angel , Sergio Gloger , Mariana Soledad Sanchez Abalos , María Victoria Chacón , Rafael Aránguiz , Paulina Orellana , Carolina Cuesta , Pablo Galeano , Lorenzo Campanelli , Gisela Vanina Novack , Luis Eduardo Martinez , Nancy Medel , Julieta Lisso , Zulma Sevillano , Nicolás Irureta , Eduardo Miguel Castaño , Laura Montrreal , Michaela Thoenes , Claudia Hanses , Stefanie Heilmann‐Heimbach , Claudia Kairiyama , Inés Mintz , Ivana Villella , Fabiana Rueda , Amanda Romero , Nancy Wukitsevits , Ivana Quiroga , Cristian Gona , Jean‐Charles Lambert , Patricia Solis , Daniel Gustavo Politis , Carlos Alberto Mangone , Christian Gonzalez‐Billault , Mercè Boada , Lluís Tàrraga , SLACHEVSKY CHONCHOL, ANDREA MARÍA , Cecilia Albala , Patricio Fuentes , Silvia Kochen , Luis Ignacio Brusco , Agustín Ruiz , Laura Morelli , Alfredo Ramírez

AbstractINTRODUCTIONGenome‐wide association studies (GWAS) are fundamental for identifying loci associated with diseases. However, they require replication in other ethnicities.METHODSWe performed GWAS on sporadic Alzheimer's disease (AD) including 539 patients and 854 controls from Argentina and Chile. We combined our results with those from the European Alzheimer and Dementia Biobank (EADB) in a meta‐analysis and tested their genetic risk score (GRS) performance in this admixed population.RESULTSWe detected apolipoprotein E ε4 as the single genome‐wide significant signal (odds ratio  = 2.93 [2.37–3.63], P = 2.6 × 10−23). The meta‐analysis with EADB summary statistics revealed four new loci reaching GWAS significance. Functional annotations of these loci implicated endosome/lysosomal function. Finally, the AD‐GRS presented a similar performance in these populations, despite the score diminished when the Native American ancestry rose.DISCUSSIONWe report the first GWAS on AD in a population from South America. It shows shared genetics modulating AD risk between the European and these admixed populations.Highlights This is the first genome‐wide association study on Alzheimer's disease (AD) in a population sample from Argentina and Chile. Trans‐ethnic meta‐analysis reveals four new loci involving lysosomal function in AD. This is the first independent replication for TREM2L, IGH‐gene‐cluster, and ADAM17 loci. A genetic risk score (GRS) developed in Europeans performed well in this population. The higher the Native American ancestry the lower the GRS values.

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Systematic Review: Genetic, Neuroimaging, and Fluids Biomarkers for Frontotemporal Dementia Across Latin America Countries

2021 , Claudia Duran-Aniotz , Paulina Orellana , Tomas Leon Rodriguez , Victoria Cabello , Fernando Henriquez , María F. Aguirre-Pinto , Tamara Escobedo , Leonel T. Takada , Stefanie D. Pina-Escudero , Oscar Lopez , Jennifer S. Yokoyama , Agustin Ibanez , Mario A. Parra , SLACHEVSKY CHONCHOL, ANDREA MARÍA

Frontotemporal dementia (FTD) includes a group of clinically, genetically, and pathologically heterogeneous neurodegenerative disorders, affecting the fronto-insular-temporal regions of the brain. Clinically, FTD is characterized by progressive deficits in behavior, executive function, and language and its diagnosis relies mainly on the clinical expertise of the physician/consensus group and the use of neuropsychological tests and/or structural/functional neuroimaging, depending on local availability. The modest correlation between clinical findings and FTD neuropathology makes the diagnosis difficult using clinical criteria and often leads to underdiagnosis or misdiagnosis, primarily due to lack of recognition or awareness of FTD as a disease and symptom overlap with psychiatric disorders. Despite advances in understanding the underlying neuropathology of FTD, accurate and sensitive diagnosis for this disease is still lacking. One of the major challenges is to improve diagnosis in FTD patients as early as possible. In this context, biomarkers have emerged as useful methods to provide and/or complement clinical diagnosis for this complex syndrome, although more evidence is needed to incorporate most of them into clinical practice. However, most biomarker studies have been performed using North American or European populations, with little representation of the Latin American and the Caribbean (LAC) region. In the LAC region, there are additional challenges, particularly the lack of awareness and knowledge about FTD, even in specialists. Also, LAC genetic heritage and cultures are complex, and both likely influence clinical presentations and may modify baseline biomarker levels. Even more, due to diagnostic delay, the clinical presentation might be further complicated by both neurological and psychiatric comorbidity, such as vascular brain damage, substance abuse, mood disorders, among others. This systematic review provides a brief update and an overview of the current knowledge on genetic, neuroimaging, and fluid biomarkers for FTD in LAC countries. Our review highlights the need for extensive research on biomarkers in FTD in LAC to contribute to a more comprehensive understanding of the disease and its associated biomarkers. Dementia research is certainly reduced in the LAC region, highlighting an urgent need for harmonized, innovative, and cross-regional studies with a global perspective across multiple areas of dementia knowledge.

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Biomarkers for dementia in Latin American countries: Gaps and opportunities

2022 , Mario A. Parra , ORELLANA VILLENA, VIVIANA PAULINA , Tomas Leon , Cabello G. Victoria , Rodrigo Gomez , Fernando Henriquez , Constanza Avalos , Andres Damian , Agustin Ibañez , Henrik Zetterberg , SLACHEVSKY CHONCHOL, ANDREA MARÍA , Betty M. Tijms , Jennifer S. Yokoyama , Stefanie D. Piña‐Escudero , J. Nicholas Cochran , Diana L. Matallana , Daisy Acosta , Ricardo Allegri , Bianca P. Arias‐Suárez , Bernardo Barra , Sonia M. D. Brucki , Geraldo Busatto , Paulo Caramelli , Sheila Castro‐Suarez , BEHRENS PELLEGRINO, MARIA ISABEL , Valeria Contreras , Nilton Custodio , Sergio Dansilio , Myriam De la Cruz‐Puebla , Leonardo Cruz de Souza , Monica M. Diaz , Lissette Duque , Gonzalo A. Farías , Sergio T. Ferreira , Nahuel Magrath Guimet , Ana Kmaid , David Lira , Francisco Lopera , Beatriz Mar Meza , Eliane C. Miotto , Ricardo Nitrini , Alberto Nuñez , Santiago O'Neill , John Ochoa , Maritza Pintado‐Caipa , Elisa de Paula França Resende , Shannon Risacher , Luz Angela Rojas , Valentina Sabaj , Lucas Schilling , Allis F. Sellek , Ana Sosa , Leonel T. Takada , Antonio L. Teixeira , Martha Unaucho‐Pilalumbo , Claudia Duran‐Aniotz

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Connexins in melanoma: Potential role of Cx46 in its aggressiveness

2020 , Orellana Villena, Viviana Paulina , Andrés Tittarelli , RETAMAL LUCERO, MAURICIO ANTONIO

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Cx46 hemichannel modulation by nitric oxide: Role of the fourth transmembrane helix cysteine and its possible involvement in cataract formation

2019 , RETAMAL LUCERO, MAURICIO ANTONIO , Orellana Villena, Viviana Paulina , Nicolás J. Arévalo , Cristóbal G. Rojas , Rodolfo J. Arjona , Constanza A. Alcaíno , Wendy González , Jonathan G. Canan , Rodrigo Moraga-Amaro , Jimmy Stehberg , Luis Reuss , Guillermo A. Altenberg