Tag Archives: Fragile X syndrome

January 2014—Can one equal 600? Is it possible for a mutation in a single nucleotide base in the FMR1 gene to be as potent as a run of more than 200 triplet repeats in causing fragile X-like symptoms? That was the question Stephen T. Warren, PhD, FACMG, raised in his keynote lecture at the 2013 meeting of the Association for Molecular Pathology. Two decades ago Dr. Warren and others showed that expansion of CGG triplet runs in the FMR1 gene is responsible for fragile X syndrome, or FXS. At the AMP meeting, Dr. Warren, who received the AMP Award for Excellence in Molecular Diagnostics, presented evidence that a point mutation in an FMR1 gene with a normal CGG repeat number can also cause intellectual disability and developmental delay, just as triplet repeats do, accompanied by other, non-FXS manifestations. In at least one case, a point mutation caused the full fragile X syndrome.