The purpose of this Notice of Funding Opportunity (NOFO) is to fund clinical trials of products evaluating efficacy and/or safety in support of a new indication or change in labeling to address unmet needs in rare neurodegenerative diseases for children and adults. Through the support of collaborative, efficient, and/or innovative clinical trials, FDA expects to increase the number of approved treatments for rare neurodegenerative diseases and exert a broad and positive impact on rare disease drug development.