FXN protomutations are the source of pathogenic expanded GAA alleles in Friedreich ataxia and explain its unequal population distribution.

FXN proto-mutations (long normal alleles) as the evolutionary source of pathogenic expanded GAA alleles

This Human Molecular Genetics study demonstrates that proto-mutations in FXN — long normal alleles (LN, ≥12 triplets) — are the evolutionary source of pathogenic expanded GAA alleles in Friedreich ataxia. These proto-mutations expand intergenerationally, explaining the unequal population distribution of the disease.

Synthesis written by Geno'X. For the full original abstract, please refer to the source publication.

Understanding the source of expanded alleles in FRDA has direct implications for transmission risk prediction and genetic counseling with intermediate alleles, potentially influencing diagnostic threshold definitions.

Clinical impact: 2/3 · Evidence strength: 3/3 · Novelty: 2/2 · Sample size: 1/1 · Publication status: 1/1 → Total: 9/10