Clinical and Genetic Findings in a Chinese Cohort of Dentatorubral–Pallidoluysian Atrophy Patients

Objective Dentatorubral–pallidoluysian atrophy (DRPLA) is a rare, inherited neurodegenerative disorder caused by the expansion of cytosine–adenine–guanine repeats in ATN1 . Most studies on DRPLA to date are limited to case reports. We aimed to provide a comprehensive summary of the clinical, genetic, biological, and magnetic resonance imaging characteristics of DRPLA using cross‐sectional baseline data. Methods This is a cross‐sectional observational cohort study. We used an extensive battery of assessments, included clinical phenotypes, genotypes, cognitive performance, biological markers, and magnetic resonance imaging characteristics. Results We enrolled 116 DRPLA patients, including 96 manifest patients and 20 prodromal patients. We identified a previously unreported ATN1 haplotype consisting of 8 single‐nucleotide polymorphisms. Cognitive assessments revealed that 51 manifest patients (96%) and 4 prodromal patients (29%) scored <26 on the Montreal Cognitive Assessment. Manifest patients showed impairments across all cognitive domains, whereas prodromal patients showed deficits only in phonemic fluency. Biological analyses showed significantly elevated plasma neurofilament light levels in manifest patients compared with prodromal patients ( P < 0.001) and healthy controls ( P < 0.001). Magnetic resonance imaging findings revealed widespread gray matter loss across the whole brain in manifest patients, whereas prodromal patients showed gray matter loss localized to the bilateral cerebellar hemispheres. Interpretation This is the first DRPLA cohort study to comprehensively report clinical, genetic, cognitive, imaging, and plasma neurofilament light data. This study provides robust data to enhance our understanding of the overall features of DRPLA. We also propose clear definitions for the preclinical stage of DRPLA, and demonstrate the high diagnostic utility of plasma neurofilament light as a biomarker. ANN NEUROL 2025;98:750–761