CLINICAL-DIAGNOSIS OF HETEROZYGOUS DYSTROPHIN GENE DELETIONS BY FLUORESCENCE IN-SITU HYBRIDIZATION

Two-thirds of patients affected by Duchenne or Becker muscular dystrop hy (DMD/BMD) carry large intra-genic deletions in the dystrophin gene. In males, the deletions can be efficiently detected using multiplex p olymerase chain reaction (PCR) and Southern blotting. In contrast, del etion detection in carrier females is complicated by the presence of a normal gene copy on the second X-chromosome. We have analyzed the bou ndaries of 570 deletions and 34 duplications in the dystrophin gene id entified in the Sao Paulo and Leiden diagnostic laboratories. The data were used to select an optimal set of cosmid probes for the detection of the most frequently deleted areas of the dystrophin gene. Six cosm ids were evaluated in fluorescence in situ hybridization (FISH) experi ments to assess deletions in 21 heterozygous deletion-carriers and nin e controls. No discrepancy was found between the FISH analysis and the molecular data, demonstrating the accuracy of the technique for carri er detection in Duchenne and Becker muscular dystrophy. (C) 1998 Elsev ier Science B.V. All rights reserved.