Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Consensus Characterization of 16 FMR1 Reference Materials: A Consortium Study by the Fragile Xperts



Jean A. Wilson, Victoria M. Pratt, Amit Phansalkar, Kasinathan Muralidharan, W E. Highsmith, J C. Beck, Scott Bridgeman, Ebony M. Courtney, Lidia Epp, Andrea Ferreira-Gonzalez, Nick L. Hjelm, Leonard Holtegaard, Mohamed A. Jama, J P. Jakupciak, Monique A. Johnson, Paul Labrousse, Elaine Lyon, Thomas W. Prior, C D. Richards, Kristy L. Richie, Benjamin B. Roa, Elizabeth M. Rohlfs, Tina Sellers, Stephanie Sherman, Karen M. Siegrist, Lawrence M. Silverman, Joanna Wiszniewska, Lisa Kalman


Fragile X (FX) syndrome is caused by expansion of a (CGG)n repeat in the FMR1 gene, occurs in approximately 1:3500 males and causes mental retardation/behavioral problems. Smaller (CGG)n repeat expansions in FMR1, premutations, are associated with reproductive risk, premature ovarian failure and FX-associated tremor/ataxia syndrome. An FMR1-sizing assay is technically challenging because of high GC content of the (CGG)n repeat, the size limitations of conventional PCR, and a lack of reference materials available for test development/validation and routine quality control. The Centers for Disease Control and Prevention (CDC) and the Association for Molecular Pathology, together with the genetic testing community, have addressed the need for characterized FX reference materials by developing characterized DNA samples from 16 cell lines with repeat lengths representing important phenotypic classes and diagnostic cutoffs. The alleles in these materials were characterized by consensus analysis in nine clinical laboratories. Southern analysis revealed allele instability in one. The information generated from this study is available on the CDC and Coriell Cell Repositories websites. DNA purified from these cell lines is available to the genetics community through the Coriell Cell Repositories. The public availability of these reference materials should help to ensure the accuracy of clinical FX genetic testing.
Journal of Molecular Diagnostics


FMR1, fragile X syndrome, molecular diagnostics, proficiency testing, quality assurance, reference materials


Wilson, J. , Pratt, V. , Phansalkar, A. , Muralidharan, K. , Highsmith, W. , Beck, J. , Bridgeman, S. , Courtney, E. , Epp, L. , Ferreira-Gonzalez, A. , Hjelm, N. , Holtegaard, L. , Jama, M. , Jakupciak, J. , Johnson, M. , Labrousse, P. , Lyon, E. , Prior, T. , Richards, C. , Richie, K. , Roa, B. , Rohlfs, E. , Sellers, T. , Sherman, S. , Siegrist, K. , Silverman, L. , Wiszniewska, J. and Kalman, L. (2021), Consensus Characterization of 16 FMR1 Reference Materials: A Consortium Study by the Fragile Xperts, Journal of Molecular Diagnostics (Accessed April 21, 2024)
Created October 12, 2021