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PubMed1992

Identification of new markers in Xp21 between DXS28 (C7) and DMD.

Characterization of Xp21 distal to Duchenne muscular dystrophy (DMD) in the region containing the genes for adrenal hypoplasia congenita (AHC) and glycerol kinase deficiency (GKD) has been limited due to a paucity of probes. Two probes were localized between DXS28 (C7) and AHC, the yeast artificial chromosome insert YHX39 (DXS727) and the polymorphic phage clone QST59 (DXS319). A genomic clone, FT1 (DXS726), 3' to DMD, was also characterized. Portions of the three probes were sequenced and primer pairs were generated to amplify a sequence-tagged site within each probe. Amplification of DNA from patients confirmed the deletion results obtained by Southern blot analysis, and these three sequence-tagged sites were successfully combined for triplex PCR. In addition to facilitating molecular genetic diagnosis in Xp21, these probes can be used to identify additional YACs and other probes to further increase the genomic information and diagnostic capabilities in this region.

Base Sequence↗
PubMed2001

Dystrophin and Dp71, two products of the DMD gene, show a different pattern of expression during embryonic development in zebrafish.

Dystrophin, the protein defective in Duchenne muscular dystrophy (DMD), plays a critical role in the formation and maintenance of the neuromuscular junction. In addition to dystrophin, activation of internal promoters of the DMD gene leads to the production of several short products. Among these, Dp71, which consists of the C-terminal domain of dystrophin, is the most abundant product of the gene in non-muscle tissues and brain. In this report, we compare the temporal and regional expression patterns of dystrophin and Dp71 at different stages of embryonic development and during retinal differentiation in zebrafish. The Dp71 transcripts are the earliest to be expressed at 9-10 h post-fertilization (hpf) in the axial mesoderm. As development proceeds, intense Dp71 staining is observed in the notochord, the developing brain, the marginal regions of the somites and the eye primordium. At the completion of retinal differentiation, Dp71 is expressed in the ganglion and inner nuclear layers. Transcripts encoding dystrophin have a slightly later onset of expression, 13-14 hpf, and remain restricted to the transverse myosepta through all the developmental stages examined. The complementary patterns of expression of dystrophin and Dp71 suggest that these two proteins exert different functions during embryonic development in zebrafish.

Animals↗
PubMed2000

Opposite pi-face selectivity for the DMD and m-CPBA epoxidations of chiral 2,2-dimethyloxazolidine derivatives of tiglic amides: control by steric interactions versus hydrogen bonding

[formula: see text] A high extent but opposite sense in the diastereoselectivity has been observed for the DMD and m-CPBA epoxidations of the optically active tiglic amides (S)-1 with 2,2-dimethyloxazolidines as chiral auxiliaries. This unprecedented reversed pi-facial differentiation for these two peroxidic oxidants is rationalized in terms of like (lk) and unlike (ul) transition structures: For DMD, steric interactions dominate, such that the unlike transition structure is favored, while for m-CPBA, hydrogen-bonding effects overcome these steric repulsions and the like one is preferred.

Journal Article↗
PubMed2002

Chimeric snRNA molecules carrying antisense sequences against the splice junctions of exon 51 of the dystrophin pre-mRNA induce exon skipping and restoration of a dystrophin synthesis in Delta 48-50 DMD cells.

Deletions and point mutations in the dystrophin gene cause either the severe progressive myopathy Duchenne muscular dystrophy (DMD) or the milder Becker muscular dystrophy, depending on whether the translational reading frame is lost or maintained. Because internal in-frame deletions in the protein produce only mild myopathic symptoms, it should be possible, by preventing the inclusion of specific mutated exon(s) in the mature dystrophin mRNA, to restore a partially corrected phenotype. Such control has been previously accomplished by the use of synthetic oligonucleotides; nevertheless, a significant drawback to this approach is caused by the fact that oligonucleotides would require periodic administrations. To circumvent this problem, we have produced several constructs able to express in vivo, in a stable fashion, large amounts of chimeric RNAs containing antisense sequences. In this paper we show that antisense molecules against exon 51 splice junctions are able to direct skipping of this exon in the human DMD deletion 48-50 and to rescue dystrophin synthesis. We also show that the highest skipping activity was found when antisense constructs against the 5' and 3' splice sites are coexpressed in the same cell.

Animals↗
PubMed2000

Contrasting evolutionary histories of two introns of the duchenne muscular dystrophy gene, Dmd, in humans.

The Duchenne muscular dystrophy (Dmd) locus lies in a region of the X chromosome that experiences a high rate of recombination and is thus expected to be relatively unaffected by the effects of selection on nearby genes. To provide a picture of nucleotide variability at a high-recombination locus in humans, we sequenced 5. 4 kb from two introns of Dmd in a worldwide sample of 41 alleles from Africa, Asia, Europe, and the Americas. These same regions were also sequenced in one common chimpanzee and one orangutan. Dramatically different patterns of genetic variation were observed at these two introns, which are separated by >500 kb of DNA. Nucleotide diversity at intron 44 pi = 0.141% was more than four times higher than nucleotide diversity at intron 7 pi = 0.034% despite similar levels of divergence for these two regions. Intron 7 exhibited significant linkage disequilibrium extending over 10 kb and also showed a significant excess of rare polymorphisms. In contrast, intron 44 exhibited little linkage disequilibrium and no skew in the frequency distribution of segregating sites. Intron 7 was much more variable in Africa than in other continents, while intron 44 displayed similar levels of variability in different geographic regions. Comparison of intraspecific polymorphism to interspecific divergence using the HKA test revealed a significant reduction in variability at intron 7 relative to intron 44, and this effect was most pronounced in the non-African samples. These results are best explained by positive directional selection acting at or near intron 7 and demonstrate that even genes in regions of high recombination may be influenced by selection at linked sites.

Africa↗
PubMed1989

The DMD gene analysed by field inversion gel electrophoresis.

Genomic and cDNA probes were used to construct a physical map of the DMD region including the 2.3 Mb DMD gene. FIGE-analysis allows rapid screening of the complete region using only a few probes, detecting deletions or duplications in over 60% of the patients. The technique is especially powerful in the analysis of carrier females. We have found two mutational hotspots; a minor hotspot located proximally and a major hotspot within a large, centrally located intron. Deletions involving this latter intron were studied using 100 kb of cloned DNA sequences. Although breakpoints are spread over the entire region, 5 are clustered within 3 kb. Analysis of over 250 BMB/DMD families has underscored the importance of germinal mosaicism as a major diagnostic pitfall. At least 14% of new mutation cases involve germinal mosaicism and this still is a lower estimate, due to small family sizes. Hence, relatives of apparent new mutation patients should be considered to have high risk, and require appropriate counselling.

Electrophoresis↗
PubMed1994

Population Pharmacokinetics of Digoxin in Duchenne Muscular Dystrophy (DMD) Patients.

Routine clinical pharmacokinetic data collected from Duchenne muscular dystrophy (DMD) patients receiving digoxin have been analyzed to evaluate the role of patients' characteristics for estimating dosing regimens. The data were analyzed using NONMEM, a computer program designed for population pharmacokinetic analysis that allows pooling of data. The pharmacokinetic model of digoxin was described using a one-compartment steady-state model. The effect of factors on digoxin clearance was investigated. NONMEM estimates indicate that digoxin clearance was influenced by the variables of body weight and combination with diuretics. The interindividual variability in digoxin clearance was modeled with proportional error with an estimated coefficient of variation of 25%, and the intraindividual variability in digoxin concentration was modeled with equal error with an estimated standard deviation of 0.0828 ng ml(minus sign1). In order to determine whether the population parameters obtained in this study were accurate, we administered digoxin according to individual dosage regimens in four DMD patients, using these values obtained by the Bayesian method. As a result, we found that mean prediction error, which indicates the deviation of prediction accuracy for digoxin concentration in plasma, was small, as were mean absolute prediction error and root mean squared error, showing the accuracy of this prediction method. The dosing method based on clearance values obtained by NONMEM analysis allowed the prediction of the steady-state concentration as a function of maintenance dose with acceptable error for therapeutic drug monitoring.

Journal Article↗
PubMed2006

Disruption of DMD and deletion of ACSL4 causing developmental delay, hypotonia, and multiple congenital anomalies.

We have studied a male patient with significant developmental delay, growth failure, hypotonia, girdle weakness, microcephaly, and multiple congenital anomalies including atrial (ASD) and ventricular (VSD) septal defects. Detailed cytogenetic and molecular analyses revealed three de novo X chromosome aberrations and a karyotype 46,Y,der(X)inv(X) (p11.4q11.2)inv(X)(q11.2q21.32 approximately q22.2)del(X)(q22.3q22.3) was determined. The three X chromosome aberrations in the patient include: a pericentric inversion (inv 1) that disrupted the Duchenne muscular dystrophy (DMD) gene, dystrophin, at Xp11.4; an Xq11.2q21.32 approximately q22.2 paracentric inversion (inv 2) putatively affecting no genes; and an interstitial deletion at Xq22.3 that results in functional nullisomy of several known genes, including a gene previously associated with X-linked nonsyndromic mental retardation, acyl-CoA synthetase long chain family member 4 (ACSL4). These findings suggest that the disruption of DMD and the absence of ACSL4 in the patient are responsible for neuromuscular disease and cognitive impairment.

Abnormalities, Multiple↗
PubMed2006

Therapeutic modulation of DMD splicing by blocking exonic splicing enhancer sites with antisense oligonucleotides.

Antisense oligonucleotides (AONs) can be used to correct the disrupted reading frame of Duchenne muscular dystophy patients (DMD). We have a collection of 121 AONs, of which 79 are effective in inducing the specific skipping of 38 out of the 79 different DMD exons. All AONs are located within exons and were hypothesized to act by steric hindrance of serine-arginine rich (SR) protein binding to exonic splicing enhancer (ESE) sites. Indeed, retrospective in silico analysis of effective versus ineffective AONs revealed that the efficacy of AONs is correlated to the presence of putative ESE sites (as predicted by the ESEfinder and RESCUE-ESE software). ESE predicting software programs are thus valuable tools for the optimization of exon-internal antisense target sequences.

Dystrophin↗
PubMed1999

Public perception of DDS versus DMD degrees.

There are currently two degrees awarded to dental graduates from U.S. dental schools. The aim of this study was two-fold: (1) to determine the level of confusion among lay personnel concerning these degrees and (2) to identify and explore any basis for any public opinion. Five hundred and twenty-four lay persons were interviewed in Cleveland and the surrounding area. Chi-square analyses were employed to determine the effects of gender, frequency of dental visits, types of dental insurance, education level, age, income, and race on public perception of the DDS and DMD degrees. Fewer than 20% of those interviewed knew that a DDS and DMD received the same level of training. Of those who indicated there was a difference in training, 69% felt that DMDs had more training than DDSs. Since the majority of lay persons were confused about the two degrees, the establishment of one unified dental degree may contribute to a better public understanding of the education and capabilities of dentists.

Adult↗
PubMedDate not supplied

[Treatment progress of Duchenne Muscular Dystrophy (DMD)].

Duchenne muscular dystrophy (DMD) is a common lethal disease for which no effective treatment is currently available. There exists a mouse model of the disease in which the usefulness of gene therapy was established. However, no progress towards human application was made due to the lack of a proper method for gene delivery. During the past several years, researchers acquired data which led them to believe that bone marrow stem cells are capable of generating not only blood cells, but also liver, heart, skin, muscle, and other tissue. Although the term "stem cell plasticity" became very popular, other studies have suggested that bone marrow might contain different types of stem cells that can produce non-hematopoietic cells. For example, mesenchymal stem cell (MSC) in bone marrow give rise to osteocytes, chondrocytes, adipocytes, and skeletal muscle. Recently, researchers have been able to show that transplanted bone marrow cells can contribute to muscle cells in a human patient who was diagnosed with two genetic diseases: severe combined immunodeficiency (SCID) and Duchenne muscular dystrophy. The odds of this happening is estimated at one in seven million. The results of studying this patient's medical history were reported by collaborating researchers at Children's Hospital, Los Angeles and Children's Hospital, Boston in an article titled "Long-term persistence of donor nuclei in a Duchenne muscular dystrophy (DMD) patient receiving bone marrow transplantation" published in the September 2002 issue of the Journal of Clinical Investigation. This patient was transplanted 15 years ago at Children's Hospital Los Angeles with paternal HLA-haploidentical T cell-depleted bone marrow. He engrafted and became a hematopoietic chimera having T and NK lymphocytes of donor origin. Studies performed on the muscle biopsy from the patient 13 years after transplantation demonstrated that the muscle showed evidence of donor derived nuclei. In addition, analysis of his bone marrow showed that small numbers of MSC were also derived from the transplanted bone marrow. Unfortunately, there was no evidence that the number of new muscle cells from the donor was able to decrease the progression of his muscular dystrophy. The revelation of finding the donor's cells in the muscle of the patient provides new hope for patients with the same disease. In the future it may be possible for mesenchymal cells to be isolated, ex vivo expanded and transplanted into patients with muscle diseases.

Animals↗
PubMed1992

Somatic reversion/suppression in Duchenne muscular dystrophy (DMD): evidence supporting a frame-restoring mechanism in rare dystrophin-positive fibers.

Many Duchenne muscular dystrophy (DMD) patients are known to have rare staining dystrophin-positive fibers, termed "revertants." The precise etiology of these rare fibers is unknown. The most likely explanation, however, is somatic mosaicism or somatic reversion/suppression. Immunocytochemistry was performed on serial sections from deleted and nondeleted patients, with a panel of antibodies--9219, 1377, 9218, and Dys-2--that span dystrophin. Both familial and nonfamilial patients possessed revertants. Either the same clusters or individual revertant fibers stained with amino- and carboxyl-terminal antibodies in all 14 DMD patients. In patients with deletions, revertants did not stain with antibodies raised to polypeptide sequences within the deletion. These results indicate that positively staining fibers are not the result of somatic mosaicism in deleted patients. Five of 10 patients without deletions had revertant fibers. In two of these patients, the revertant fibers did not stain with antibody 9218, which was generated against amino acids 2305-2554 and which corresponds to exons 48-52. The remaining antibodies from the panel stained the same fibers on separate serial sections in these two patients. The most likely mechanism giving rise to these positively staining fibers is a second site in-frame deletion. Antibodies generated to polypeptide sequences within deletions can be used to control for the natural occurrence of revertant fibers in myoblast transfer studies and may be useful in the detection of point mutations.

Antibodies↗
PubMed2005

[DMDUse of fetal specific antibody-HbF to detect fetal erythroblasts for non-invasive prenatal diagnosis of DMD].

Maternal blood was obtained at 8-26 weeks of gestation. After discontinuous density gradient centrifugation with Percoll, HbF antibody was used to identify fetal NRBC. The precise differentiation between fetal and maternal NRBC is based on the constitutional difference between fetal and adult hemoglobin (Hb). Fetal cells appear yellow cytoplasmic staining,while adult cells colorless. NRBCs were collected by micromanipulation and whole genome amplification was performed. DMD was prenatally diagnosed by using the combination of sex determination,multiplex PCR and linkage analysis of several STR sites of dystrophin. NRBCs stained with HbF were found in all of 20 maternal blood samples with gestations, and 7 fetuses with risk of DMD were diagnosed. We concluded that HbF antibody could identify fetal NRBC efficaciously, and this is a kind of more prospective application method.

Antibodies↗
PubMed1991

[CT findings of muscular dystrophy: limb girdle type (LG), myotonic type (MYD) and Duchenne type (DMD)].

CT scans of muscles in patients with LG, MYD and DMD were obtained at five different body levels: the neck, L3 vertebral body, pelvic girdle, thigh and lower leg. CT numbers, cross sectional areas (CSA) and %CSA of muscle or fat were evaluated in each muscle. The characteristic CT patterns for each type of muscular dystrophy were obtained. Compared with DMD, the gracilis and soleus were more severely damaged in LG and the biceps femoris remained relatively preserved among the hamstrings. In addition, the multifidus of the neck and sternocleidomastoid also were more severely damaged in MYD. This study suggests that CT scan will be useful in the differential diagnosis of these types of muscular dystrophy as well as in planning appropriate rehabilitation and detecting damaged muscles.

Adolescent↗
PubMed1994

A report on 528 intragenic deletions detected in DMD and BMD patients by an Italian collaborative study.

The results of a collaborative study involving about one third of the total DMD and BMD cases living in the Italian territory are reported. The analysis of the breakpoint frequency by intron revealed significant differences among regional groups of DMD patients (for introns 2, 11 and 50 in Sardinia and for introns 9 and 45 in northeastern Italy), whereas no regional differences were observed among regional groups of BMD patients. These differences involve the same Italian regions which previous studies, performed by different markers, identified as "genetically differentiated". The data support the possibility of a differential distribution among populations of some intronic sequences, facilitating the origin of deletion breakpoints within the dystrophin gene.

Dystrophin↗
PubMed1995

Detection of DMD gene deletions in Thai children patients.

For the dystrophin gene, it has been shown that about 65% of DMD/BMD patients have detectable deletions. The majority of deletions are clustered in exons 45-53 and at the 5' terminus. We studied 14 X-linked muscular dystrophy (DMD) Thai child patients for detection of gene deletions by amplification of nine exons plus the promoter of the dystrophin gene in two multiplex polymerase chain reactions that included hot spot region (exons 45-53 and 5' terminus). There were 8 DMD patients who had incomplete gene deletion and most of the deletions were around exon 49. PCR-base assays will allow deletion detection from dry blood spot samples and prenatal diagnosis.

Age of Onset↗
PubMed1995

DMD and BMD in the same family due to distinct mutations.

We report on a family with a boy affected by Duchenne muscular dystrophy (DMD) and an asymptomatic cousin with a Becker-type dystrophin abnormality, diagnosed by chance. Dystrophin gene analysis showed that these conditions were caused by two distinct deletions with breakpoints in different exons. In Xp21 families, DNA analysis and dystrophin testing of asymptomatic males with high CK plasma levels might detect different dystrophin mutations in separate haplotypes as in our family, although we stress there should be clear clinical or familial indications for such testing.

Adolescent↗
PubMed2003

Pseudoexon activation in the DMD gene as a novel mechanism for Becker muscular dystrophy.

We report the characterization of two deep intronic mutations in the Duchenne muscular dystrophy (DMD) gene of two unrelated Becker muscular dystrophy (BMD) patients, causing the aberrant inclusion of a pseudoexon in the mature transcripts. These two mutations were identified by the use of RT-PCR on transcripts isolated from muscle. The first abnormally large transcript resulting from a 58-bp insertion between exon 62 and exon 63 was identified in a BMD patient with mental retardation. The origin of this transcript was a mutation in intron 62 (IVS62-285A>G), which resulted in the occurrence of a high quality donor splice site. The IVS25+2036A>G in intron 25 was identified in a subclinical BMD patient with high CK levels. The mutation reinforces the strength of a pre-existing acceptor splice site, resulting in activation of an intronic pseudoexon of 95 bp. By using DHPLC, the patient's mother was found to be a somatic mosaic. The insertion of these newly recognized extra exons leads to premature termination codons, but we could observe that some degree of normal splicing was taking place in both patients. The detection of these residual full length transcripts is consistent with the clinical presentation and dystrophin analyses. This is the first report of pseudoexon activation as a mechanism for Becker muscular dystrophy, and this reveals further the diversity of genetic abnormalities causing BMD.

Adult↗