Study on Duchenne muscular dystrophy gene mutation and prenatal diagnosis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the characteristics of DNA mutations underlying Duchenne muscular dystrophy and provide prenatal diagnosis.</p><p><b>METHODS</b>Multiplex ligation-dependent probe amplification (MLPA) and denaturing high performance liquid chromatography (DHPLC) were applied for analyzing DMD gene mutations in 388 unrelated Chinese patients and 53 fetuses.</p><p><b>RESULTS</b>Respectively, 230 and 43 subjects were found to harbor a deletion (59.28%) or duplication (11.08%). Two deletion hotspots were identified, which have located at exons 45-54 and exons 3-19. Duplications were mainly detected at exons 2-43. Point mutations were identified in 29.64% of patients. Fifty three fetuses were prenatal diagnosed, among which 18 were identified as patients.</p><p><b>CONCLUSION</b>Frequencies of DMD gene deletions and duplications in China are similar to global data. Prenatal diagnosis can help to reduce births of DMD patients.</p>

Correlation between genotypes and phenotypes in pseudohypertrophic muscular dystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the correlation between genotypes and phenotypes in Chinese patients with pseudohypertrophic muscular dystrophy.</p><p><b>METHODS</b>Patients with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) were diagnosed clinically. Multiplex ligation-dependent probe amplification (MLPA) were performed to detect potential DMD gene mutations. The results were analyzed statistically.</p><p><b>RESULTS</b>Among 280 patients, 238(85.0%) were diagnosed with DMD, 35(12.50%) were diagnosed with BMD and 7(2.5%) were diagnosed with intermediate muscular dystrophin (IMD). Among these, 252(92.31%) were in-frame mutations, and 21(7.69%) were out-of-frame mutations. Twelve patients with DMD have carried in-frame mutations, 9 with BMD have carried frame-shift mutations, and 7 IMD patients have carried frame-shift mutation.</p><p><b>CONCLUSION</b>Most of the genotypes and phenotypes of DMD have complied with the reading-frame hypothesis. Patients with BMD with frame-shift mutations may facilitate understanding of the pathogenesis of DMD, and provide a theoretical basis for clinical therapy.</p>

Preliminary study of the spatial structural and functional changes of dystrophin after exon-3 deletion / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the structural and functional changes of dystrophin molecule after exon 3 deletion.</p><p><b>METHODS</b>Three-dimensional models of dystrophin comprising the major domains were established before and after exon 3 deletion using SWISS-MODEL server. The motifs and structural domains of dystrophin after exon 3 deletion were searched in Pfam database, and the crystal structure of the actin-binding domain in the dystrophin molecule was analyzed using Rasmol software.</p><p><b>RESULTS</b>Torsion of the N-terminal actin-binding domain occurred in the dystrophin molecule after deletion of exon 3. Homology analysis based on Pfam database searches indicated that following exon 3 deletion, the Bit score of the first calponin homology (CH1) domain was decreased from 108 to 36.5 while its expectation value increased from 2.3e-9 to 8.1e-8. The deletion also resulted in the absence of the spiral region C from the CH1 domain.</p><p><b>CONCLUSION</b>Exon 3 deletion in the dystrophin-coding sequence decreases the stability of CH1 domain and prevents the formation of the junction interface where dystrophin binds to actin. The bioinformatics approach provides a new alternative for investigation of the pathogenesis of DMD pathogenesy investigation.</p>