This Notice of Funding Opportunity (NOFO) invites new applications for Centers for Collaborative Research in Fragile X andFMR1-Associated Conditions (hereafter termed "Fragile X Centers"). Despite many remarkable advances in fundamental knowledge about FMR1-associated conditions, gaps in knowledge remain about the processes that drive the variability in clinical features (phenotypic heterogeneity) among affected individuals. In this round of competition, therefore, all centers will be required to identify an overarching theme directed at broadening our understanding of factors underlying the phenotypic heterogeneity and/or variability in response to interventions seen in one or more FMR1 associated conditions. Successful Fragile X Centers will be composed of multidisciplinary teams of basic, translational, clinical, and/or data science investigators applying precision medicine approaches (seeking to understand which mechanisms and interventions are most applicable to specific individuals or groups) to address the center's proposed overarching theme. This NOFO includes specific requirements about inclusion of research on human subjects or human phenotypic data; diversity of participants or materials being studied; the types of allowable clinical trials; and involvement of early-stage investigators. Applications that do not adhere to these requirements will be considered nonresponsive to this NOFO and will be withdrawn. In addition, this NOFO requires a Plan for Enhancing Diverse Perspectives (PEDP), which will be assessed as part of the scientific and technical peer review evaluation. Applications that fail to include a PEDP will be considered incomplete and will be withdrawn.Applicants are strongly encouraged to read the NOFO instructions carefully and view the availablePEDP guidance material.