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Diagnostic performance of plasma pTau217 in genetically admixed South American populations.

Nature communications

Authors: Pamela V Martino-Adami, Joice Coutinho de Alvarenga, Pilar Freccero, Hanna Huber, Julio Fernandez, Ivonne Carolina Bolaños Burgos, Maria Barbara Postillone, Gabriela Tomé Oliveira Engelmann, Ines Mintz, Marco Aurelio Romano Silva, Nancy Medel, Erika de Oliveira Hansen, Julieta Lisso, Natalia Dias Silva, Andréa Teixeira Carvalho, Nicolás Irureta, Débora Marques de Miranda, Mariana Vallejo-Azar, Luiz Armando Cunha de Marco, Stefanie Heilmann-Heimbach, Jonas Jardim de Paula, Silvia Kochen, Rafaela Teixeira de Ávila, Patricia Solis, Anja Schneider, Paula Gonzalez, Bernardo de Mattos Viana, Maria Carolina Dalmasso, Maria Aparecida Camargos Bicalho, Alfredo Ramírez

Plasma pTau217 is a leading biomarker for Alzheimer's disease, but evidence from genetically admixed populations in low- and middle-income countries remains limited. We evaluated the diagnostic performance of pTau217 and pTau217/Aβ42 measured using Simoa technology in memory-clinic cohorts from Brazil (Cog-Aging-Study, n = 353) and Argentina (GeNED.ar, n = 134). Here we show that both biomarkers accurately identified cerebrospinal fluid (CSF)-defined amyloid pathology in Cog-Aging-Study-Brazil and showed high concordance with clinical diagnosis across both cohorts. Classification performance was improved using two-cut-off approaches that account for diagnostic uncertainty. We further show that APOE-ε4, lower body mass index, and reduced kidney function were associated with higher pTau217 in Cog-Aging-Study-Brazil, whereas education also influenced biomarker levels in GeNED.ar-Argentina. African ancestry modified APOE-ε4 effect on CSF but not plasma biomarkers. These findings support the use of plasma pTau217-based biomarkers in genetically admixed South American populations and in settings with limited access to CSF testing and brain imaging.

© 2026. The Author(s).

PMID: 42693124

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