overview of fragile x syndrome and associated disorders
Fragile X is a group of conditions associated with changes in the Fragile X gene — called “FMRl” and located on the X chromosome. The FMRl gene can undergo changes, when inherited, which affect a pattern of DNA called “CGG repeats.” Typically, the FMRl gene has up to 54 CGG repeats, though the range between 45 and 54 repeats, is called the “intermediate” or “gray zone.” A premutation carrier has 55–200 CGG repeats, and someone with a full mutation has more than 200 CGG repeats.
When a premutation or full mutation is present, it can result in a Fragile X-associated disorder (FXD). These include: