Résumé
<p><b>OBJECTIVE</b>To conduct genetic diagnosis for a family in which no exonic deletions and duplications of the dystrophin gene were detected.</p><p><b>METHODS</b>Potential exonic deletions and duplications of the dystrophin gene were initially analyzed with using multiplex ligation-dependent probe amplification (MLPA). Subsequently, all of the 79 exons of the dystrophin gene of the proband and a pregnant woman from the family were analyzed with PCR amplification and DNA sequencing. Following identification of the causative mutation, prenatal diagnosis was provided.</p><p><b>RESULTS</b>MLPA analysis had detected no exonic deletions and duplications of the dystrophin gene. Sequence analysis has identified a C>T mutation on the 22nd nucleotide position of the 70th exon of the dystrophin gene (c.10108 C>T), which has replaced the codon CGA to a stop codon (TGA). The patient's mother and sister were both heterozygous for the same mutation. Upon prenatal diagnosis, the fetus was found to be positive for the Y chromosome sex-determining gene (SRY) and has carried above mutation. The result of short tandem repeat linkage analysis also confirmed that the fetus has inherited the mutant X chromosome.</p><p><b>CONCLUSION</b>The causative mutation of the dystrophin gene has been discovered in an affected family, which has enabled prenatal diagnosis of the disease.</p>