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FMR1 Premutation

Meaning

The FMR1 Premutation is a specific genetic alteration characterized by an unstable, intermediate expansion of the cytosine-guanine-guanine (CGG) trinucleotide repeat sequence within the FMR1 gene located on the X chromosome, typically falling within a range of 55 to 200 repeats. Although this range does not cause the full Fragile X syndrome, this premutation is clinically associated with a spectrum of distinct conditions, most notably Fragile X-associated primary ovarian insufficiency (FXPOI) in female carriers and Fragile X-associated tremor/ataxia syndrome (FXTAS) in older carriers. It represents a critical, often unrecognized, genetic factor influencing both reproductive and neurodegenerative health trajectories.