Clinical Research Directory

Inclusion Criteria: 1. Ability to provide written informed consent (and assent, when required based on age and local requirements) before participation. 2. Confirmed disease-causing (pathogenic) variant in the FUS gene, verified by an approved genetic testing laboratory and reviewed by the program geneticist. 3. Age 10 years or older, with test results, signs, or symptoms showing ongoing loss of motor nerve cells consistent with amyotrophic lateral sclerosis (ALS). 4. Medical ability to undergo repeated injections into the fluid surrounding the spinal cord and other program-related procedures. 5. Lung function (slow vital capacity \[SVC\]) of 30% or greater. 6. Stable medications and nutritional support for at least 1 month before entering the program. 7. Willingness to follow the program's pregnancy prevention requirements: * Females must not be pregnant or breastfeeding and must either be unable to become pregnant, practice true abstinence, or use a highly effective method of birth control during the program and for at least 40 weeks after the last dose. * Males must practice true abstinence, be surgically sterile, or use a highly effective method of birth control during the program and for at least 40 weeks after the last dose if sexually active with a partner who could become pregnant. 8. Patients who previously participated in the FUSION study and completed Part 3 can enroll. Exclusion Criteria: 1. Any active or ongoing medical condition that, in the opinion of the treating physician, may increase the risk of treatment with ulefnersen. 2. Any medical condition or circumstance that makes repeated spinal taps (lumbar punctures) unsafe or unsuitable. 3. Expected need for treatment with blood-thinning medicines (anticoagulants) or medicines that reduce blood clotting (antiplatelet medications) during the program, as determined by the treating physician.