v3.26.1
Segment Information - Information On The Segment And Reconciliation To Net Loss (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses $ 25,150 $ 17,760
Total general and administrative expenses 8,199 8,159
Net loss (30,934) (22,647)
Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses 25,150 17,760
Total general and administrative expenses 8,199 8,159
Other income 2,415 3,272
Net loss (30,934) (22,647)
Rett syndrome | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses 11,037 4,524
Batten disease | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses 178 845
Early Discovery | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses 613 1,287
Personnel-related | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses 6,456 5,404
Total general and administrative expenses 2,626 2,484
Stock-based compensation | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses 1,791 1,570
Total general and administrative expenses 1,838 2,478
Manufacturing | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses 4,197 3,107
Other | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total research and development expenses 878 1,023
Total general and administrative expenses 1,723 1,288
Professional and consultant fees | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total general and administrative expenses 1,402 1,277
Office-related | Reportable Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Total general and administrative expenses $ 610 $ 632