Fragile x premutations, mechanisms and modifiers - overall abstract: fragile x-associated conditions (fxacs) are a heterogeneous group of disorders arising from alterations in the size and…

The National Institute of Child Health and Human Development awarded $3.231 million to Regents of the University of Michigan on September 11, 2025, under the Child Health and Human Development Extramural Research program (CFDA 93.865) to support Fragile X Premutations, Mechanisms and Modifiers research conducted in Michigan.

The award funds three integrated research projects addressing genetic, pathologic, and environmental factors underlying premutation-associated Fragile X disorders—specifically Fragile X syndrome, Fragile X-associated tremor/ataxia syndrome, and Fragile X-associated primary ovarian insufficiency. The research applies data-driven genomic and bioinformatics approaches to understand how FMR1 CGG repeat expansions cause disease and to identify novel therapeutic targets. The work is structured as a center that engages mechanistic crosstalk between these conditions and between the FMR1 locus and related repeat expansion disorders.

The performance period extends through August 31, 2030. University of Michigan performs work as the prime recipient through its Office of Research and Sponsored Projects Division.

Two sub-recipients contribute specialized research functions. Emory University (award issued February 18, 2026) provides phenotypic and molecular studies from patients with FXTAS and FXPOI, including IRB submissions, subject identification and tracking via REDCap database, laboratory analysis, and data interpretation and publication support. Baylor College of Medicine (award issued February 10, 2026) leads Project 2, developing and maintaining FXTAS and FXPOI mouse models for testing modifier gene mutations and coordinating sequence analyses of human samples through BCM's Human Genome Sequencing Center.

Fragile x premutations, mechanisms and modifiers - overall abstract: fragile x-associated conditions (fxacs) are a heterogeneous group of disorders arising from alterations in the size and epigenetic state of a polymorphic CGG repeat within FMR1. Described as the first repeat expansion disorder over 30 years ago, FMR1 CGG repeat expansions cause neurological, reproductive, and neurodevelopmental diseases while also serving as an archetype for understanding repeat expansions and the mechanisms by which they elicit dysfunction. Work over decades delineated the native functions of the fragile x protein, fmrp, and the consequences of its loss and identified toxic gain-of-function mechanisms (DNA toxicity induced by r-loop formation, RNA toxicity mediated by protein sequestration, and protein mediated toxicity from repeat associated non-AUG (ran) translation) elicited by transcribed CGG repeats. Despite these advances, we lack effective therapies for any fxac - at least in part due to the enigmatic clinical heterogeneity and incomplete penetrance of fxacs that confound targeted approaches. Here we propose a change in our approach to fxacs. Rather than focusing solely on specific diseases (fragile x syndrome (FXS), fragile x-associated tremor/ataxia syndrome (fxtas), or fragile x-associated primary ovarian insufficiency (fxpoi)), the center structure enables US to directly engage the mechanistic crosstalk between conditions and between the FMR1 locus and related repeat expansion disorders. Our central hypothesis is that a deeper understanding of genetic, pathologic, and environmental factors which underlie the variable clinical manifestations of premutation (PM)-associated disorders will reveal novel insights into both how repeats cause disease and how we can target them therapeutically. We will address this hypothesis in three highly integrated projects all focused on premutation disorders. These projects will use data-driven genomic and bioinformatics approaches coupled with emerging tools and multiple model systems. Our outstanding team of experts from four leading sites of fragile x research features both junior and senior investigators and runs the gamut from clinicians to neuroscientists to geneticists to reproductive biology experts. By pooling our substantial data, expertise and resources, we will pursue identification of novel pathogenic mechanisms in FX premutation disorders and develop a series of robust and viable targets and approaches for therapeutic development in fxacs.