Bi-allelic intermediate ATXN2 repeat expansions are associated with slow progressing, leg-onset familial ALS. - Demaegd KC; Koole W; van Vugt JJ; Dankbaar JW; Hendrikse J; Nazlı Başak A; de Carvalho M; Corcia P; Codron P; Bernard E; Guissart C; Couratier P; et al. (BMJ neurology open, 2026)