Molecular Diagnosis of Fragile X Syndrome and AGG Interspersion Analysis

Abstract

Two molecular techniques used for studying Fragile X syndrome were tested in this study. The first technique detemines the number of CGG repeats in the FRAXA repeat region. The second examines the number of CGG repeats without AGG interspersions. The first technique used PCR (polymerase chain reaction) to specifically amplify DNA from the repeat region that had been cut by the restriction enzyme Hind III. Then the amplified DNA size was determined using agarose gels stained with ethidium bromide The first technique demonstrated that it could accurately determine the number of CGG repeats in most individuals. Thus, it shows promise in identifying individuals that do not need further fragile X testing. The second technique also amplified Hind III cut DNA. This DNA was then purified and cut with the restriction enzyme Mnll. These fragments were then also separated on an agarose gel and stained with ethidium bromide. The second technique demonstrated an ability to identify large regions of pure CGG repeats at the FRAXA site. This technique may in the future provide a method of determining premutation stability.