Preprint finds altered cortisol homeostasis in FMR1 full mutation and premutation carriers
A cohort study of 891 individuals screened for FMR1 CGG-repeat expansions reports dysregulation of glucocorticoid signalling pathways in both fragile X syndrome and FXTAS.
A preprint posted to bioRxiv describes altered cortisol homeostasis and glucocorticoid signalling in individuals carrying CGG-repeat expansions in the FMR1 gene, covering both the full mutation range (causing fragile X syndrome, FXS) and the premutation range (associated with fragile X-associated tremor/ataxia syndrome, FXTAS).
FXS is the most common inherited cause of intellectual disability; FXTAS is a neurodegenerative condition that typically manifests in older premutation carriers. The genetic mechanisms underlying both are well characterised — silencing of FMR1 protein (FMRP) in the full mutation, and RNA toxicity in the premutation — but the contribution of neuroendocrine pathways has received comparatively little attention.
The authors screened a clinically referred cohort of 891 individuals using conventional and methylation-specific PCR for FMR1 CGG-repeat status, then examined markers of glucocorticoid signalling. They report that both full-mutation and premutation carriers show evidence of disrupted cortisol regulation relative to controls, suggesting that glucocorticoid pathway dysregulation may be a shared feature across the FMR1 expansion spectrum. The authors propose this could have implications for understanding the broader clinical phenotype in FMR1-related disorders. As a preprint, these findings await formal peer review and independent replication.
Plain-language version
For patients, families, and general readers. Educational only — not medical advice.
Fragile X syndrome is the most common inherited form of intellectual disability; it is caused by a large repetition of a DNA sequence in a gene called FMR1. People who carry a smaller repetition — called a premutation — do not usually have fragile X syndrome but can develop a different condition called FXTAS (fragile X-associated tremor/ataxia syndrome), which affects movement and memory in older age. Researchers looked at nearly 900 people screened for these FMR1 gene changes and found that both groups showed differences in how their bodies regulate a stress hormone called cortisol, compared with people without the gene changes. Cortisol is produced by the adrenal glands and plays many roles in the body's stress response and metabolism. The researchers suggest that problems with cortisol regulation may be part of what makes these conditions difficult for affected individuals. This is early-stage research shared as a preprint, meaning it has not yet been independently checked by other scientists.
This is an educational summary, not medical advice. If anything here raises questions for you, please speak with your GP or a clinical professional.
Sources
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Primary sourcePreprint bioRxiv (Cold Spring Harbor Laboratory) · 2026-10-24Cortisol homeostasis and glucocorticoid signaling are altered in FMR1 full mutation and premutation carriers.