FIREFISH (NCT02913482) is an ongoing, multicentre, open-label, two-part, seamless study aiming to asses the safety and efficacy of risdiplam (RG7916) in babies aged 1–7 months with Type 1 SMA and two SMN2 gene copies. Part 1 is dose finding for Part 2. Primary endpoints for Part 1 are safety, tolerability and PK/PD of risdiplam, whereas for Part 2 primary endpoints are percent of infants sitting without support for 5 seconds at 12 months assesed by Gross Motor Scale of the BSID-III.