The team described a fully humanized ATN1 mouse bearing a CAG expansion of 112 repeats to model dentatorubral‑pallidoluysian atrophy (DRPLA). This mutation is known to produce earlier, more severe disease when repeat size is larger; investigators reported that the Atn1Q112/+ line was highly seizure prone and experienced early mortality when left untreated. Short, observable seizures occurred spontaneously in untreated mutant mice during chronic monitoring. These features align the model with the young‑onset, treatment‑resistant seizure phenotype seen clinically in some DRPLA cases.
Investigators administered an investigational antisense oligonucleotide (ASO) designed to target human, CAG‑expanded ATN1 at two timepoints: postnatal day 2 (P2) and again at four weeks of age. The preprint described acute seizure threshold testing, formal ataxia profiling, and chronic in vivo video‑EEG recording for spontaneous seizures through eight weeks of age as primary functional endpoints. The article did not report exact ASO dosing amounts or detailed pharmacokinetic data in the main text.
Data indicated that saline‑treated Atn1Q112/+ mice had greater seizure susceptibility in acute challenge paradigms compared with wild‑type controls, and a higher rate of early death. Investigators observed that ASO‑treated Atn1Q112/+ mice showed normalization of seizure threshold in acute testing. In other words, the ASO intervention shifted acute seizure measures in mutants toward values seen in wild‑type animals. The report tied early mortality to untreated seizure susceptibility but did not provide granular cause‑of‑death pathology in the preprint.
Chronic video‑EEG recordings captured spontaneous behavioral seizures in saline‑treated Atn1Q112/+ mice over a two‑week window. The study team reported that these spontaneous events were absent in both ASO‑treated Atn1Q112/+ mice and in wild‑type mice. Concomitant EEG analysis showed a mutation‑driven decrease in delta and theta frequency power in Atn1Q112/+ mice. The preprint linked this spectral change to mutant ATN1 expression; the ASO‑treated mutants lacked the spontaneous seizures observed in untreated mutants.
Ataxia profiling formed part of the functional assessment. Investigators recorded measurable ataxia in saline‑treated Atn1Q112/+ mice relative to wild‑type. ASO administration decreased ataxia metrics in mutant mice, indicating a motor benefit coincident with seizure protection. The manuscript did not enumerate the complete ataxia scoring rubric or provide individual test values in the abstract section, though the authors described improved motor outcomes after ASO treatment.
Collectively, the preclinical dataset indicated that an ASO targeting human, expanded ATN1 reduced seizure susceptibility in acute testing, prevented spontaneous seizures captured by video‑EEG, decreased ataxia signs, and protected against early death in this humanized DRPLA model. Investigators concluded that the Atn1Q112/+ mouse validates a clear epilepsy phenotype for DRPLA research and suggests ATN1 as a modifiable risk factor for therapeutic development using antisense approaches.
The article is a preprint and has not undergone peer review. The authors declared no competing interests and acknowledged funding from organizations including CureDRPLA and the American Epilepsy Society. Important methodological details were not reported in the abstract: the specific ASO dose amounts, full pharmacokinetic or toxicology assessments, and detailed histopathologic causes of early death were not included in the source article body provided here. Longer‑term efficacy beyond eight weeks of age, dose‑response relationships, and translational safety data remain open questions that the authors did not resolve in this preprint. These points represent the next steps needed before moving an antisense strategy targeting ATN1 toward clinical translation.