The purpose of this funding opportunity announcement (FOA), issued by NINDS, is to invite applications for a study of candidate biomarkers in Spinal Muscular Atrophy (SMA). The study will be done using the NeuroNEXT infrastructure (as established in response to RFA-NS-11-009, RFA-NS-11-010, RFA-NS-11-008) along with ad hoc clinical sites as appropriate. This is a milestone-driven cooperative agreement program involving participation of NIH staff in the development of the project plan and monitoring of research progress.