Translation of the FMR1 premutation phenotypes across the lifespan - carriers of the FMR1 premutation allele (FXPM) are at risk to develop fragile X-associated tremor/ataxia syndrome (FXTAS) and…

The University of South Carolina received a $419,459 Project Grant from the National Institute of Child Health and Human Development (NICHD) under the Child Health and Human Development Extramural Research program (CFDA 93.865) beginning September 10, 2025, and concluding August 31, 2030. This P50 Center grant supports a comprehensive, lifespan-based research initiative titled "Translation of the FMR1 Premutation Phenotypes Across the Lifespan" designed to advance understanding of Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) and Fragile X-associated Neuropsychiatric Disorders (FXAND) in carriers of the FMR1 premutation allele. The center employs a developmental approach examining these conditions across multiple age groups to identify novel mechanisms and intervention targets, addressing critical knowledge gaps regarding risk prediction, clinical manifestation timing, and sex-based variation.

The research deliverables include two primary projects: Project 1 examines the developmental trajectory of social communication deficits and their relationship to FXAND in young children (ages 3-5), investigating the predictive roles of auditory processing and molecular-genetic variation; Project 2 establishes the timing and developmental trajectory of language and vocal phenotypes predictive of FXTAS-related motor, cognitive, and psychiatric symptoms in women across the lifespan (ages 35-80). Research activities are conducted collaboratively through sub-awards to Rush University Medical Center (FMR1 genotyping and FMRP quantification), the University of Wisconsin System (behavioral phenotype and genotype-phenotype relationship expertise), and the Medical University of South Carolina (neuromotor assessment and hearing impairment analysis). Together, these coordinated efforts generate clinical phenotype characterization data and mechanistic insights intended to inform future intervention development and improve outcomes for affected individuals and families.

Translation of the FMR1 premutation phenotypes across the lifespan - carriers of the FMR1 premutation allele (FXPM) are at risk to develop fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated neuropsychiatric disorders (FXAND). Despite significant impacts including functional limitations, reduced quality of life, poor health, and even reduced life expectancy associated with these conditions,1-3 tremendous knowledge gaps exist that constrain accurate risk prediction and treatment. Variation across age, developmental stages, and SEX has not been sufficiently quantified for FXTAS and FXAND. This lack of knowledge translates to poor understanding on whether, when, and how these FMR1-associated conditions emerge and affect individuals and families. The overall objective of this P50 center, "translation of the FMR1 premutation phenotypes across the lifespan," is to advance understanding of the clinical phenotypes and underlying mechanisms associated with FXTAS and FXAND through the application of a developmental approach that examines these conditions across the lifespan. This P50 FX center proposal addresses this critical need to characterize the FXPM phenotype across the lifespan in a non-biased sample that will identify novel mechanisms and targets for intervention. To accomplish this objective, the FX center will capitalize on strong collaborations among investigators across two projects. Project 1 - aim: identify the developmental trajectory of social communication deficits and their relationship to FXAND in 3 to 5-year-olds with FXPM. Determine the extent to which auditory processing and molecular-genetic variation (i.e., CGG repeat length, mrna, fmrp, activation ratio in females) predict social communication across age (ROBERTS/HOGAN). Project 2 - aim: establish the timing, developmental trajectory and prodromal language/vocal phenotypes predictive of FXTAS-related motor, cognitive, and psychiatric symptoms in FXPM women across 35 to 80 years of age. Identify how age, clinical risk factors, and molecular-genetic variation (i.e., CGG repeat length, mrna, fmrp, activation ratio) and environmental adversity interact and influence FXTAS risk in women (KLUSEK).