Citations

Importance Friedreich ataxia (FA), a fatal, autosomal recessive disorder caused by pathogenic variants in the frataxin ( FXN ) gene, is characterized by progressive neurologic and cardiac disease, with cardiac disease being the major cause of death. Preclinical studies have demonstrated that systemic administration of AAVrh.10hFXN, an rh.10 serotype cardiotropic adenoassociated virus (AAV) vector expressing the normal human FXN coding sequence, reverses the cardiomyopathy in FXN-deficient mice. Objective To assess the safety and preliminary efficacy of administration of AAVrh.10hFXN to adults with FA cardiomyopathy. Design, Setting, and Participants This nonrandomized clinical trial evaluates the pooled data of 2 independent, open-label, dose-escalation trials that used the same gene therapy vector and similar clinical protocols among patients with FA cardiomyopathy at academic medical centers. Data were collected from February 22, 2022, to October 4, 2025, for trial 1 and from February 14, 2023, to September 10, 2025, for trial 2 and analyzed together from November 5, 2025, to March 12, 2026. Intervention AAVrh.10hFXN, administered intravenously in 3 dose cohorts (1.8 × 10 11 , 5.6 × 10 11 , and 1.2 × 10 12 vector genomes per kilogram of body weight). Main Outcomes and Measures In addition to safety as the primary outcome, multiple parameters of exploratory end points were assessed, including cardiac biopsy levels of FXN protein, cardiac magnetic resonance imaging–derived left ventricular mass index (LVMI), and serum high-sensitivity (hs) troponin I. Results Seventeen patients with FA cardiomyopathy (mean [SD] age, 25 [6] years; 11 [65%] female) were followed up for a mean (SD) of 20 (8) months. There were 4 serious adverse events, 3 possibly related to prednisone immunosuppression and 1 possibly vector-related myocarditis 12 months after therapy, all of which resolved. Other adverse events were transient, nonserious, or not treatment related. In all 8 patients with cardiac biopsy 3 months after therapy, there were higher levels of cardiac FXN (dose cohort 1, 20%; cohort 2, 81%; cohort 3, 123%). After therapy, LVMI was lower by at least 10% in 9 patients and stabilized in 8 patients. Excluding the patient with myocarditis, posttherapy values of serum hs troponin I were lower by at least 10% in 15 patients and higher by at least 10% in 2 patients. Conclusions and Relevance Findings of this nonrandomized clinical trial suggest that intravenous administration of AAVrh.10hFXN was well tolerated and may be a potential treatment for FA cardiomyopathy, as evidenced by preliminary improvement in exploratory efficacy end points. Trial Registration ClinicalTrials.gov Identifiers: NCT05302271 and NCT05445323

ABSTRACT Background Monoclonal gammopathy of thrombotic significance (MGTS) is a recently described chronic prothrombotic condition characterized by monoclonal anti-PF4 antibodies that are detected above the polyclonal antibody background in patient sera (i.e. present as monoclonal gammopathy of undetermined significance, MGUS). Due to conflicting data in the published literature on antibody clonality in heparin-induced thrombocytopenia (HIT), we evaluated clonality and abundance of anti-PF4 antibodies in HIT, including investigating whether an MGUS, if present in HIT, represents the causative anti-PF4 antibody. Methods Blood samples from 15 patients with HIT were subject to Platelet Factor 4-dependent antigen-based and functional tests. The unmanipulated serum antibody repertoire and isolated anti-PF4 antibodies were subjected to mass spectrometric evaluation. Results Two of the 15 HIT patients had an IgG MGUS. Notably, anti-PF4 antibodies were not synonymous with the MGUS antibody in either of the two patients. Eight of the 15 patients demonstrated monoclonal anti-PF4 antibodies, however, none of the anti-PF4 antibodies were detectable as an MGUS upon evaluation of the entire serum antibody repertoire, reflecting their low abundance. In the seven patients with multiple anti-PF4 antibodies, non-monoclonality was confirmed by analysis of deglycosylated antibody heavy chains. Conclusions Anti-PF4 HIT antibodies are monoclonal in approximately 50% of HIT patients, however, antibody abundance is low such that they are not detectable over the polyclonal IgG background (i.e. are MGUS-negative), differentiating HIT from MGTS. This observation helps explain the transient nature of HIT relative to the persistent prothrombotic state seen in MGTS.

Abstract INTRODUCTION White matter lesions on fluid‐attenuated inversion recovery magnetic resonance imaging (FLAIR‐MRI) reflect small vessel disease (SVD) and aid in identifying vascular contributions to impairment and dementia (VCID). Emerging diffusion MRI (dMRI) biomarkers are sensitive to early SVD but the lack of validated approaches for defining dMRI abnormality has limited their clinical utility. METHODS In 3934 participants (8749 observations) from a population‐based sample, we classified 9% as vascular cognitive impairment versus not (VCI+/VCI−) using abnormal FLAIR‐MRI and cognitive testing. We evaluated four distinct dMRI positivity criteria and assessed performance in an independent clinical sample. RESULTS The young referent criterion performed best and yielded an estimated prevalence of dMRI positivity aligned with pathology literature. About 40% of the population were dMRI positive, and these individuals had lower baseline cognition and faster longitudinal decline. Cutpoints were validated in an independent clinical sample. DISCUSSION The proposed dMRI abnormality framework can detect VCID and aid in identification of individuals at risk of VCI.

ABSTRACT Background and Objectives Converging evidence hints at neurodevelopmental effects in genetic frontotemporal degeneration (FTD). In cross-sectional studies, for some genes, young adult FTD variant carriers show differences in brain volumes and cognition compared to familial non-carriers. However, longitudinal trajectories may more sensitively capture FTD-related neurodevelopmental vs. neurodegenerative changes than cross-sectional approaches. This study examined longitudinal trajectories of brain volumes, executive function, and plasma biomarkers in young adult carriers compared to familial non-carriers, as measures of neurodevelopmental and neurodegenerative outcomes of FTD-causing variants. Methods This longitudinal cohort study comprised participants, aged 18-30 years, from the FTD Prevention Initiative across Europe, Canada, and the USA. Genetic groups included C9orf72 (47%), MAPT (30%), and GRN (23%). Linear mixed-effects models were computed to assess longitudinal outcomes across age between groups, controlling for sex, scanner (for brain volumes), and education (for executive function); random effects accounted for between-subject variability nested within family membership. Results Variant carriers ( n =147) and familial non-carriers ( n =113) did not differ in age (mean±SD, 25.9±3.2 years), sex (53% female), or number of visits (2.1±1.7). Young adult C9orf72 repeat expansion carriers exhibited smaller thalamic volumes than non-carriers at the reference age of 26 years ( b =-982.8mm 3 , SE=317.0, p= 0.0046, f 2 =0.32), with relatively stable trajectories across ages 18-30 (i.e., no change over time). Trajectories of rostral anterior cingulate volumes differed in C9orf72 carriers and non-carriers across age, where carriers showed relatively stable trajectories and non-carriers showed age-appropriate declines ( b =64.4mm 3 , SE=29.9, p= 0.035, f 2 =0.07). For MAPT and GRN , there were little to no differences in total brain, cortical, or subcortical volumes between groups and over time. No longitudinal differences were observed between carriers and non-carriers in executive function, or plasma NfL or GFAP for any genetic group. Discussion C9orf72 repeat expansions were linked to smaller average thalamic volumes and stable trajectories between ages 18 to 30, supporting potential neurodevelopmental origins. The modest evidence supporting an absence of difference in neurodegenerative biomarkers and executive function suggests minimal early neurodegeneration and functional preservation in young adulthood.