RAPID ANTIBODY-TEST FOR DIAGNOSING FRAGILE-X-SYNDROME - A VALIDATION OF THE TECHNIQUE

To date, the identification of patients and carriers of the fragile X syndrome has been carried out by DNA analysis by means of the polymera se chain reaction and Southern blot analysis. This direct DNA analysis allows both the size of the CGG repeat and methylation status of the FMR1 gene to be determined. We have recently presented a rapid antibod y test on blood smears based on the presence of FMRP, the protein prod uct of the FMR1 gene, in lymphocytes from normal individuals and the a bsence of FMRP in lymphocytes from patients. Here, we have tested the diagnostic value of this new technique by studying FMRP expression in 173 blood smears from normal individuals and fragile X patients. The d iagnostic power of the antibody test is ''perfect'' for males, whereas the results are less specific for females.