Detection of genomic duplications and deletions of the DMD gene in affected males and female carriers by using mutiplex ligation-dependent probe amplification / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect genomic deletion and duplication mutations in the dystrophin gene of the Duchenne muscular dystrophy (DMD) patients and their potential female carriers.</p><p><b>METHODS</b>Genomic deletions and duplications of the DMD gene in 32 affected males and 27 potential female carriers were screened by mutiplex ligation-dependent probe amplification (MLPA).</p><p><b>RESULTS</b>Of the 32 investigated affected males, 24 were detected to have deletions of one or more exons of the DMD gene, 1 patient had a duplication from exon 5 to 55, 1 patient had a nonsense point mutation (R768X) in exon 19, the other 6 affected males were predicted to have possible disease-causing point mutations. MLPA analysis showed a DMD deletion or duplication in 18 female relatives, and the female carriers had the same deletion or duplication as their probands, respectively.</p><p><b>CONCLUSION</b>MLPA analysis is proven to be an efficient tool for identification of both affected males and female carriers of DMD rearrangements in cases in which the disease-causing mutation in the affected male was not known. It could provide useful information for the genetic counseling of the family involved.</p>

Identification of deletion/duplication mutations in DMD gene by multiple ligation probe amplification and denaturing high-performance liquid chromatography / 中国医学科学院学报

<p><b>OBJECTIVE</b>To compare the effectiveness of using multiple ligation probe amplification (MLPA) and denaturing high-performance liquid chromatography (DHPLC) in screening the exon deletions and duplications of the DMD gene.</p><p><b>METHODS</b>MLPA technique was applied to detect exon deletions and duplications previously confirmed by denaturing high-performance liquid chromatography (DHPLC).</p><p><b>RESULTS</b>From October 2004 to October 2005, 22 unrelated DMD probands and their possible female relatives with clinical diagnosis with dystrophinopathy at our hospital entered this study. Both DHPLC and MPLA detected DMD gene depletion in 11 probands and DMD duplications in 3 probands. MLPA detected deletions and duplications in 2 probands, which were not detected by DHPLC. MLPA also successfully identified the carriage status of the potential female carriers of the probands.</p><p><b>CONCLUSION</b>Compared with DHPLC and traditional PCR techniques, MLPA is a superior tool to analyze the deletions and duplications in affected males as well as in the identification of the carriage status of potential females carriers.</p>

Sibling brother and sister both with Duchenne muscular dystrophy / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the clinical and lab features of sibling brother and sister both with Duchenne muscular dystrophy (DMD).</p><p><b>METHODS</b>We conducted comprehensive clinical and lab investigations including the test of serum enzymes, electromyography (EMG), electrocardiography, color Doppler echocardiography, HE staining of skeletal muscles, immunohistochemical study of dystrophin and utrophin, multiple ligation probe amplification (MLPA) on exon 1-79 of dystrophin gene, and short tandem repeat-poly- merase chain reaction of CA repeats located in dystrophin gene.</p><p><b>RESULTS</b>These two patients were confirmed to suffer from DMD. They were characterized by typical features of DMD including typical clinical manifestations, increased serum enzymes, EMG presenting myogenic impairment, HE staining presentation belonging to DMD, negative dystrophin in brother, and inconstantly positive on the sarcolemma of sister. Furthermore, no deletion or duplication was found in the 1-79 exons of dystrophin gene. The suffering brother and sister carried the same maternal X chromosome.</p><p><b>CONCLUSIONS</b>Carriers of DMD gene show typical clinical and laboratory manifestations of DMD. Comprehensive examinations should be performed for such carriers.</p>

Identification of disease-causing point mutations in DMD patients' dystrophin gene without large deletions/duplications / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect the disease-causing point mutations in the dystrophin gene of Duchenne muscular dystrophy (DMD) patients.</p><p><b>METHODS</b>The approach of denaturing high performance liquid chromatography (DHPLC) coupling with sequencing was used to screen the point mutations of 79 exons and the untranslated regions of dystrophin gene without large deletions/duplications, which was in 6 unrelated DMD probands from 6 DMD families.</p><p><b>RESULTS</b>Five disease-causing mutations, 697-698insGT, C616T, G1255T, C4279T, and C2302T, were ides created the new stop codons in downstream sites of mutations, respectively. In addition to the disease-causing point mutations, a point mutation T5586+61A in intron 39 was also found at patient 3, and a missense mutation A694T in exon 8 was detected at patient 5. Four point mutations, C2168+13T, 5740-13dupG, G5234A and C5280T, were also detected at patient 6 whose causative point mutation was unavailable. Seven point mutations have not been reported previously. Bi-directional PCR amplification of specific alleles (Bi-PASA) method was established to distinguish the haplotypes of heterozygote or homozygote in a single PCR reaction.</p><p><b>CONCLUSION</b>Via automated DHPLC screening or detecting the subexonic mutations in dystrophin gene is feasible to clinical laboratories, and also is a superior method in terms of sensitivity and efficiency.</p>

Transfection and in vitro expression of human microdystrophin gene in rat mesenchymal stem cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct the eukaryotic expression vector of human microdystrophin gene and observe its expression in rat mesenchymal stem cells (rMSCs) in vitro.</p><p><b>METHODS</b>The plasmid PBSK-MICRO containing human microdystrophin cDNA was digested by restriction endonuclease, and the resultant microdystrophin fragment was inserted into the NotI site of pcDNA3.1(+) to prepare the eukaryotic expression vector-pcDNA3.1(+)/ microdystrophin, which was identified by endonuclease digestion and sequencing. The recombinant plasmid was transfected into rMSCs via lipofectamine, and after G418 selection, the expression of microdystrophin was detected by RT-PCR and indirect immunofluorescence assay.</p><p><b>RESULTS</b>Microdystrophin gene fragment was correctly inserted into the plasmid pcDNA3.1(+), as conformed by sequencing and digestion with Not I and Hind III. The total mRNA of the transfected rMSCs was extracted and microdystrophin mRNA expression was found in the cells by RT-PCR. Indirect immunofluorescence assay for the protein expression of microdystrophin showed bright red fluorescence in the transfected rMSCs.</p><p><b>CONCLUSION</b>Eukaryotic expression plasmid pcDNA3.1(+)/microdystrophin has been constructed successfully and microdystrophin can be expressed in transfected rMSCs in vitro, which may facilitate further research of Duchenne muscular dystrophy treatment by genetically modified allogeneic stem cell transplantation.</p>