Molecular genetic testing of the FMR1 gene is commonly performed in clinical laboratories. Pathogenic variants in the FMR1 gene are associated with fragile X syndrome, fragile X–associated tremor ataxia syndrome (FXTAS), and fragile X–associated primary ovarian insufficiency (FXPOI). This document provides updated information regarding FMR1 pathogenic variants, including prevalence, genotype–phenotype correlations, and variant nomenclature. Methodological considerations are provided for Southern blot …
