Fragile X messenger ribonucleoprotein 1 pre-messenger RNA (FMR1 pre-mRNA)

Fragile X messenger ribonucleoprotein 1 (FMR1) pre-messenger RNA is the primary transcript of the FMR1 gene, which encodes a protein essential for synaptic plasticity and cognitive development. The FMR1 pre-mRNA is a significant therapeutic target due to its role in Fragile X-associated tremor/ataxia syndrome (FXTAS), where a premutation expansion of CGG repeats (55-200) in the 5' untranslated region leads to an RNA gain-of-function toxicity. This expanded pre-mRNA sequesters essential RNA-binding proteins and undergoes repeat-associated non-AUG (RAN) translation, resulting in the accumulation of toxic protein aggregates such as FMRpolyG. Therapeutic strategies targeting FMR1 pre-mRNA include antisense oligonucleotides (ASOs) and small molecules that aim to either degrade the transcript via RNase H or prevent the sequestration of proteins by the CGG repeats. While Fragile X Syndrome (FXS) is characterized by the silencing of this transcript, FXTAS and related premutation disorders are driven by the presence of the expanded mRNA, making its reduction a primary goal for disease-modifying therapy.

Other names

FMR1 precursor mRNAFragile X mental retardation 1 pre-mRNAFMR1 transcriptFMR1 mRNA

Antisense oligonucleotides (ASOs) bind to the FMR1 pre-mRNA to trigger RNase H-mediated degradation or to sterically block the CGG repeat region, thereby preventing the sequestration of RNA-binding proteins and inhibiting the production of toxic RAN-translated proteins.