Mutations In Duchenne Muscular Dystrophy Gene Research Articles

Gestational Outcomes of Pregnant Women Who Have Had Invasive Prenatal Testing for the Prenatal Diagnosis of Duchenne Muscular Dystrophy

Aim To show the importance of prenatal diagnosis of Duchenne Muscular Dystrophy (DMD) and to demonstrate the effect of DMD gene mutations on gestational outcomes. Materials and Methods We retrospectively evaluated 89 pregnancies in 81 individuals who were referred to Hacettepe University for prenatal diagnosis of DMD between January 2000 and December 2015. Prenatal diagnostic methods (chorionic villus sampling (CVS): 66, amniocentesis (AC): 23) were compared for test results, demographic features, and obstetric outcomes of pregnancies. The female fetuses were divided into two groups according to the DMD status (healthy or carrier) to understand the effect of DMD gene mutations on obstetric outcomes. Results Eight prenatally diagnosed disease-positive fetuses were terminated. There was no statistically significant difference between the CVS and AC groups in terms of study variables. There were 46 male fetuses (51.6%) and 43 female fetuses (48.4%). Fifteen of the female fetuses were carriers (34.8%). Median birthweight values were statistically insignificantly lower in the carrier group. Conclusion Pregnancies at risk for DMD should be prenatally tested to prevent the effect of disease on families and DMD carrier fetuses had obstetric outcomes similar to DMD negative female fetuses.

A novel canine model for Duchenne muscular dystrophy (DMD): single nucleotide deletion in DMD gene exon 20

BackgroundBoys with Duchenne muscular dystrophy (DMD) have DMD gene mutations, with associated loss of the dystrophin protein and progressive muscle degeneration and weakness. Corticosteroids and palliative support are currently the best treatment options. The long-term benefits of recently approved compounds such as eteplirsen and ataluren remain to be seen. Dogs with naturally occurring dystrophinopathies show progressive disease akin to that of DMD. Accordingly, canine DMD models are useful for studies of pathogenesis and preclinical therapy development. A dystrophin-deficient, male border collie dog was evaluated at the age of 5 months for progressive muscle weakness and dysphagia.Case presentationDramatically increased serum creatine kinase levels (41,520 U/L; normal range 59–895 U/L) were seen on a biochemistry panel. Histopathologic changes characteristic of dystrophinopathy were seen. Dystrophin was absent in the skeletal muscle on immunofluorescence microscopy and western blot. Whole genome sequencing, polymerase chain reaction, and Sanger sequencing revealed a frameshift, single nucleotide deletion in canine DMD exon 20, position 27,626,466 (c.2841delT mRNA), resulting in a stop codon six nucleotides downstream. Semen was archived for future line perpetuation.ConclusionsThis spontaneous canine dystrophinopathy occurred due to a novel mutation in the minor DMD mutation hotspot (between exons 2 through 20). Perpetuating this line could allow for preclinical testing of genetic therapies targeted to this area of the DMD gene.

DMD mutation and LTBP4 haplotype do not predict onset of left ventricular dysfunction in Duchenne muscular dystrophy.

Cardiomyopathy develops in >90% of Duchenne muscular dystrophy (DMD) patients by the second decade of life. We assessed the associations between DMD gene mutations, as well as Latent transforming growth factor-beta-binding protein 4 (LTBP4) haplotypes, and age at onset of myocardial dysfunction in DMD. DMD patients with baseline normal left ventricular systolic function and genotyping between 2004 and 2013 were included. Patients were grouped in multiple ways: specific DMD mutation domains, true loss-of-function mutations (group A) versus possible residual gene expression (group B), and LTBP4 haplotype. Age at onset of myocardial dysfunction was the first echocardiogram with an ejection fraction <55% and/or shortening fraction <28%. Of 101 DMD patients, 40 developed cardiomyopathy. There was no difference in age at onset of myocardial dysfunction among DMD genotype mutation domains (13.7±4.8 versus 14.3±1.0 versus 14.3±2.9 versus 13.8±2.5, p=0.97), groups A and B (14.4±2.8 versus 12.1±4.4, p=0.09), or LTBP4 haplotypes (14.5±3.2 versus 13.1±3.2 versus 11.0±2.8, p=0.18). DMD gene mutations involving the hinge 3 region, actin-binding domain, and exons 45-49, as well as the LTBP4 IAAM haplotype, were not associated with age of left ventricular dysfunction onset in DMD.

A retrospective analysis of 237 Chinese families with Duchenne muscular dystrophy history and strategies of prenatal diagnosis.

To offer 4-year clinical prenatal diagnosis experience of Duchenne muscular dystrophy (DMD). Denaturing high-performance liquid chromatography (DHPLC) and Sanger sequencing were used for molecular diagnosis of 237 DMD families. In the study, deletions, duplications, complex rearrangement and small mutations accounted for 47.3%, 8.4%, 1.7% and 42.6% of 237 families, respectively. Sixty-six different deletion patterns were identified in 112 families. Fourteen different duplication patterns were identified in 20 families and 4 complex rearrangements were identified. About 87.1% different small mutation patterns were identified, including 37.6% different nonsense mutation patterns, 24.8% different frameshift mutation patterns, 7.9% different missense mutation patterns, and 16.8% different splice site mutation patterns. There was no significant difference in the age of onset and mutation patterns (P>.05). The follow-up examinations revealed that the pregnancies of 14 cases were interrupted. Two cases were preterm births, 151 cases were delivered at term, 63 cases continued to pregnancy, and 7 cases were lost to follow-up. DHPLC and Sanger sequencing technique are efficient, sensitive, and specific in screening for DMD gene mutations. And pre-pregnancy DMD gene examination is an important step to assess mutation type of family with suspected DMD and guides exactly prenatal diagnosis in high-risk families.

A De novo Mutation in Dystrophin Causing Muscular Dystrophy in a Female Patient.

Background:Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are X-linked recessive neuromuscular diseases resulting from dystrophin (DMD) gene mutations. It has been known that the carrier of DMD mutations may also have symptoms of the disease. While de novo mutation is quite common in BMD/DMD patients, it is rarely reported in the female carriers.Methods:Two sporadic Chinese patients with progressive muscular dystrophy and their familial members were recruited. The targeted next-generation sequencing (NGS) and the multiplex ligation-dependent probe analysis (MLPA) were performed in the proband. Blood tests, electrocardiography, echocardiography, and electromyography were also evaluated.Results:Two novel mutations of DMD gene were identified, c.7318C>T (p.Q2440*) in the male proband and c.4983dupA (p.A1662Sfs*24) in the female carrier. The MLPA analysis did not detect any large rearrangements. The haplotype analysis indicated that the two mutations were derived from de novo mutagenesis.Conclusions:We identified two novel de novo mutations of DMD gene in two Chinese pedigrees, one of which caused a female patient with muscular dystrophy. The mutational analysis is important for DMD patients and carriers in the absence of a family history. The NGS can help detect the mutations in MLPA-negative patients.

P.55 - Brain involvement in Duchenne muscular dystrophy: a role for dystrophin isoform Dp71 in cell migration and proliferation

Intelligence of individuals with Duchenne muscular dystrophy (DMD) is lower than the general population. Cognitive impairment, epilepsy, autism and attention deficit hyperactivity disorder are prevalent. Mounting evidence links these symptoms to the loss of dystrophin in the brain; yet central nervous system involvement in DMD has been largely ignored. The most predominant dystrophin isoform in the brain is the smaller Dp71 isoform expressed in neurons and glia. Distal DMD mutations affecting Dp71 expression are linked to cognitive impairment. The function(s) of Dp71 and how its absence can lead to cognitive and behavioural symptoms are not well understood. We are modelling the loss of Dp71 both endogenously in DMD patient-derived fibroblasts (which, in controls, naturally express Dp71) and with siRNA in neuronal and glial cell lines. Four patient fibroblast cell lines, each harbouring a different DMD gene mutation that naturally results in the loss of Dp71 are being studied. Accompanying clinical data confirms these patients display cognitive and/or behavioural symptoms, which is severe for two individuals. Our preliminary findings highlight a role for Dp71 in cell migration and proliferation; alterations in these processes are associated with psychiatric disorders prevalent in DMD such as autism. We will present would healing and proliferation assay data exploring these role(s) and discuss potential molecular mechanisms behind the cognitive and behavioural symptoms observed in DMD. The high risk of neuropsychiatric syndromes in Duchene warrants early intervention to achieve the best possible quality of life; our findings have significant potential to inform ongoing drug development in this area.

The natural history of the patients with Duchenne muscular dystrophy in Taiwan: A medical center experience

Duchenne muscular dystrophy (DMD) is the most common hereditary muscular dystrophy and caused by DMD gene mutation. In addition to progressive proximal muscle weakness, respiratory, orthopedic, and gastrointestinal complications are often observed in DMD. The natural history of patients with DMD in Taiwan has not been reported thus far. Medical records of 39 patients who received a diagnosis of DMD between 1999 and 2016 at Kaohsiung Medical University Hospital were reviewed. The diagnosis of DMD was confirmed through muscle biopsy or DMD genetic analysis. The mean onset age and mean follow-up period were 2.75 years and 6.76 years, respectively. Seventeen patients (43.5%) had a family history of DMD. The mean full intelligence quotient of the patients was 71.08, and the mean age of walking ability loss was 9.7 years (25 patients). The mean onset age of respiratory insufficiency was 10.64 years with a decline rate of 5.18% per year (25 patients). The mean onset age of cardiomyopathy was 14.69 years (seven patients). The mean onset age of scoliosis was 13.29 years with a progression rate of 11.48° per year (14 patients). Eleven (28.2%) and eight (20.5%) patients had deletions and duplications of DMD, respectively. Fourteen patients (35.9%) had point mutations or small deletions or insertions. Five patients received only multiplex ligation-dependent probe amplification (MLPA) analysis and exhibited neither deletion nor duplication. No mutation was identified in one patient through both MLPA and exon sequencing. The clinical phenotypes and disease course in our cohort were consistent with that reported in previous studies. However, the proportion of point mutations or small deletions or insertions in our study was considerably higher than that in reports from other populations. Cardiac ejection fraction was found not a reliable biomarker for identifying cardiac problems, discovering a better parameter is necessary.

A retrospective analysis of 6 children with Duchenne muscular dystrophy

To analyze the clinical features of 6 children with Duchenne muscular dystrophy (DMD) and review related literature, and to provide a basis for early diagnosis and effective treatment of this disease. A retrospective analysis was performed on the clinical data of 6 children with DMD who were admitted to the First Affiliated Hospital of Nanjing Medical University from January 2010 to October 2015. All the 6 cases were boys without a family history of DMD, and the age of diagnosis of DMD was 1.2-11.5 years. All patients had insidious onset and increases in alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, α-hydroxybutyrate dehydrogenase, creatine kinase (CK), and creatine kinase-MB, particularly CK, which was 3.3-107.2 times the normal level. Their gene detection results all showed DMD gene mutation. The gene detection results of two children's mothers showed that they carried the same mutant gene. The muscle biopsy in one case showed that the pathological changes confirmed the diagnosis of DMD. The level of CK in one case declined by 77.0% 5 days after umbilical cord blood mesenchymal stem cell transplantation. For boys with abnormal serum enzyme levels and motor function, DMD should be highly suspected. It should be confirmed by CK and DMD gene detection as soon as possible. And the progression of the disease could be delayed by early intervention for protecting the remaining normal muscle fibers.

Multiplex Ligation-Dependent Probe Amplification in X-linked Recessive Muscular Dystrophy in Korean Subjects.

PurposeDuchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are similar genetic disorders whose patterns of mutation and disease phenotypes might be expected to show differences among different countries. We analyzed multiplex ligation-dependent probe amplification (MLPA) data in a large number of Korean patients with DMD/BMD.Materials and MethodsWe obtained 130 positive MLPA results (86 DMD, 27 BMD, and 17 female carriers) from 272 candidates (237 clinically suspected patients and 35 possible female carriers) who took part in this study. We analyzed the mutation patterns among 113 patients diagnosed by MLPA and calculated deletion/duplication percentages from a total of 128 patients, including 15 patients who were diagnosed using methods other than MLPA. We also analyzed hot spot locations among the 130 MLPA-positive results.ResultsMost mutations were detected in a central hot spot region between exons 44 and 55 (80 samples, 60.6%). Unlike previous reports, a second frequently observed hot spot near the 5'-end was not distinctive. MLPA detected deletions in specific exons in 92 patients with DMD/BMD (71.8%) and duplications in 21 patients (16.4%).ConclusionOur MLPA study of a large number of Korean patients with DMD/BMD identified the most frequent mutation hot spot, as well as a unique hot spot pattern. DMD gene mutation patterns do not appear to show significant ethnic differences.

Whole genome sequencing reveals a 7 base-pair deletion in DMD exon 42 in a dog with muscular dystrophy

Dystrophin is a key cytoskeletal protein coded by the Duchenne muscular dystrophy (DMD) gene located on the X-chromosome. Truncating mutations in the DMD gene cause loss of dystrophin and the classical DMD clinical syndrome. Spontaneous DMD gene mutations and associated phenotypes occur in several other species. The mdx mouse model and the golden retriever muscular dystrophy (GRMD) canine model have been used extensively to study DMD disease pathogenesis and show efficacy and side effects of putative treatments. Certain DMD gene mutations in high-risk, the so-called hot spot areas can be particularly helpful in modeling molecular therapies. Identification of specific mutations has been greatly enhanced by new genomic methods. Whole genome, next generation sequencing (WGS) has been recently used to define DMD patient mutations, but has not been used in dystrophic dogs. A dystrophin-deficient Cavalier King Charles Spaniel (CKCS) dog was evaluated at the functional, histopathological, biochemical, and molecular level. The affected dog’s phenotype was compared to the previously reported canine dystrophinopathies. WGS was then used to detect a 7 base pair deletion in DMD exon 42 (c.6051-6057delTCTCAAT mRNA), predicting a frameshift in gene transcription and truncation of dystrophin protein translation. The deletion was confirmed with conventional PCR and Sanger sequencing. This mutation is in a secondary DMD gene hotspot area distinct from the one identified earlier at the 5′ donor splice site of intron 50 in the CKCS breed.

P.103 - DMD genotypes and loss of ambulation in the CINRG Duchenne natural history study

Objective: To correlate time to loss of ambulation (LoA) and different truncating DMD gene mutations in a large, prospective natural history study of Duchenne muscular dystrophy (DMD), with particular attention to mutations amenable to emerging molecular treatments. Methods: We analyzed data from the Cooperative International Neuromuscular Research Group Duchenne Natural History Study for participants with DMD single- or multi-exon deletions or duplications with defined exon boundaries (n = 186), or small mutations identified by sequencing (n = 26, including 16 nonsense point mutations). We performed a time-to-event analysis of LoA, a strong indicator of overall disease severity, adjusting for glucocorticoid treatment and genetic modifiers. Results: Participants with deletions amenable to skipping of exon 44 had later LoA (median 14.8 years, hazard ratio 0.31, 95% confidence interval 0.14–0.69, p = 0.004). Age at LoA did not differ significantly in participants with deletions amenable to exon 45, 51, and 53 skipping, duplications, and small rearrangements. Nonsense mutation DMD also showed a typical median age at LoA (11.1 years), with a few outliers (ambulatory around or after 16 years of age) carrying stop codons within in-frame exons, more often situated in the rod domain. Conclusions: As exon 44 skipping–amenable DMD has a later LoA, mutation-specific randomization and selection of placebo groups are essential for the success of clinical trials.

Characterization of a Dmd (EGFP) reporter mouse as a tool to investigate dystrophin expression.

BackgroundDystrophin is a rod-shaped cytoplasmic protein that provides sarcolemmal stability as a structural link between the cytoskeleton and the extracellular matrix via the dystrophin-associated protein complex (DAPC). Mutations in the dystrophin-encoding DMD gene cause X-linked dystrophinopathies with variable phenotypes, the most severe being Duchenne muscular dystrophy (DMD) characterized by progressive muscle wasting and fibrosis. However, dystrophin deficiency does not only impair the function of skeletal and heart muscle but may also affect other organ systems such as the brain, eye, and gastrointestinal tract. The generation of a dystrophin reporter mouse would facilitate research into dystrophin muscular and extramuscular pathophysiology without the need for immunostaining.ResultsWe generated a DmdEGFP reporter mouse through the in-frame insertion of the EGFP coding sequence behind the last Dmd exon 79, which is known to be expressed in all major dystrophin isoforms. We analyzed EGFP and dystrophin expression in various tissues and at the single muscle fiber level. Immunostaining of various members of the DAPC was done to confirm the correct subsarcolemmal location of dystrophin-binding partners. We found strong natural EGFP fluorescence at all expected sites of dystrophin expression in the skeletal and smooth muscle, heart, brain, and retina. EGFP fluorescence exactly colocalized with dystrophin immunostaining. In the skeletal muscle, dystrophin and other proteins of the DAPC were expressed at their correct sarcolemmal/subsarcolemmal localization. Skeletal muscle maintained normal tissue architecture, suggesting the correct function of the dystrophin-EGFP fusion protein. EGFP expression could be easily verified in isolated myofibers as well as in satellite cell-derived myotubes.ConclusionsThe novel dystrophin reporter mouse provides a valuable tool for direct visualization of dystrophin expression and will allow the study of dystrophin expression in vivo and in vitro in various tissues by live cell imaging.Electronic supplementary materialThe online version of this article (doi:10.1186/s13395-016-0095-5) contains supplementary material, which is available to authorized users.

DMD genotypes and loss of ambulation in the CINRG Duchenne Natural History Study.

To correlate time to loss of ambulation (LoA) and different truncating DMD gene mutations in a large, prospective natural history study of Duchenne muscular dystrophy (DMD), with particular attention to mutations amenable to emerging molecular treatments. We analyzed data from the Cooperative International Neuromuscular Research Group Duchenne Natural History Study for participants with DMD single- or multi-exon deletions or duplications with defined exon boundaries (n = 186), or small mutations identified by sequencing (n = 26, including 16 nonsense point mutations). We performed a time-to-event analysis of LoA, a strong indicator of overall disease severity, adjusting for glucocorticoid treatment and genetic modifiers. Participants with deletions amenable to skipping of exon 44 had later LoA (median 14.8 years, hazard ratio 0.31, 95% confidence interval 0.14-0.69, p = 0.004). Age at LoA did not differ significantly in participants with deletions amenable to exon 45, 51, and 53 skipping, duplications, and small rearrangements. Nonsense mutation DMD also showed a typical median age at LoA (11.1 years), with a few outliers (ambulatory around or after 16 years of age) carrying stop codons within in-frame exons, more often situated in the rod domain. As exon 44 skipping-amenable DMD has a later LoA, mutation-specific randomization and selection of placebo groups are essential for the success of clinical trials.

The emerging role of viral vectors as vehicles for DMD gene editing.

Duchenne muscular dystrophy (DMD) is a genetic disorder caused by mutations in the dystrophin-encoding DMD gene. The DMD gene, spanning over 2.4 megabases along the short arm of the X chromosome (Xp21.2), is the largest genetic locus known in the human genome. The size of DMD, combined with the complexity of the DMD phenotype and the extent of the affected tissues, begs for the development of novel, ideally complementary, therapeutic approaches. Genome editing based on the delivery of sequence-specific programmable nucleases into dystrophin-defective cells has recently enriched the portfolio of potential therapies under investigation. Experiments involving different programmable nuclease platforms and target cell types have established that the application of genome-editing principles to the targeted manipulation of defective DMD loci can result in the rescue of dystrophin protein synthesis in gene-edited cells. Looking towards translation into the clinic, these proof-of-principle experiments have been swiftly followed by the conversion of well-established viral vector systems into delivery agents for DMD editing. These gene-editing tools consist of zinc-finger nucleases (ZFNs), engineered homing endoculeases (HEs), transcription activator-like effector nucleases (TALENs), and RNA-guided nucleases (RGNs) based on clustered, regularly interspaced, short palindromic repeats (CRISPR)–Cas9 systems. Here, we succinctly review these fast-paced developments and technologies, highlighting their relative merits and potential bottlenecks, when used as part of in vivo and ex vivo gene-editing strategies.

Identifying Non-Duchenne Muscular Dystrophy-Positive and False Negative Results in Prior Duchenne Muscular Dystrophy Newborn Screening Programs: A Review.

Duchenne muscular dystrophy (DMD) is a candidate for the recommended universal screening panel based on evidence that early corticosteroid treatment improves outcomes and on new genetic therapies that require early diagnosis for effectiveness. Elevated creatine kinase levels in the neonatal period are the initial screening marker in DMD newborn screening programs but is found in inherited muscle disorders other than DMD. Data are needed to inform protocols for future screening and follow-up testing and care in these patients. To review non-DMD muscle disorders identified by prior DMD screening programs and to investigate whether these programs failed to identify patients later diagnosed as having DMD (false-negative findings). Since 1975, 10 DMD newborn screening programs have provided opportunities to study screening protocols, outcomes, and parental responses. These programs used elevated creatine kinase levels in dried blood spots for the initial screening, with the diagnosis of DMD based on findings of clinical follow-up, muscle biopsy, or direct mutational testing of the DMD gene. Literature regarding these prior programs was reviewed in PubMed, and the programs were discussed directly with the directors when possible to identify diagnoses of non-DMD disorders and false negative results from 1975 to July 12, 2015. Data were collected from screening programs, which were active between 1975 and December 2011. Data were analyzed from March 26, 2015, to August 24, 2015. The 10 screening programs screened more than 1.8 million newborns between 1975 and 2011, and 344 were diagnosed with DMD. Of those screened, the majority were boys. Across all programs, 80 patients had positive results for non-DMD disorders, including Becker muscular dystrophy and forms of limb-girdle and congenital muscular dystrophies, and 21 patients had false-negative findings for DMD. Screening for DMD will result in identification of other muscle diseases. Future screening protocols should include infants of both sexes and include follow-up testing algorithms to evaluate patients who do not have DMD gene mutations but may have another muscle disorder associated with elevated neonatal creatine kinase levels. These programs will need to be aware that false-negative results are a possibility.

Aspects génétiques et moléculaires des dystrophinopathies

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are caused by mutations in the DMD gene that encodes the cytoskeletal protein, dystrophin. Dystrophinopathies are inherited in an X-linked recessive manner. Due to the tremendous size of the gene (2.2 megabases), the DMD locus has a high spontaneous mutation rate, and one third of sporadic cases of DMD are due to a de novo mutation. There are seven tissue-specific promoters in the gene. The skeletal muscular transcript contains 79 exons and encode the full-length protein (427-kDa) located at the inner face of the sarcolemma of muscle fibers. DMD gene mutations are highly heterogeneous. Large rearrangements (deletions or duplications of one or more exons) are most frequently involved while point mutations account for 20 %-30 % of cases. A survey of current strategies of molecular diagnosis is presented here. In particular, the role of muscle biopsy (for dystrophin and RNA analyses) in the diagnosis of dystrophinopathies is discussed. In more than 90 % of cases, the clinical severity is correlated with the impact of the mutations on the reading frame and the expression of the dystrophin (absence or residual amount of mutated protein). Various mechanisms contribute to the exceptions. Besides the clinical interest for the patient, the identification of the mutation allows accurate genetic counseling in the familles, and is a necessary prerequisite for the inclusion of the patient in the genotype-based clinical trials.

Detection of a recurrent de novo mutation in a Chinese family affected with Duchenne muscular dystrophy

To provide genetic analysis for a family affected with Duchenne muscular dystrophy (DMD) with a recurrent de novo mutation. Multiplex ligation dependent probe amplification (MLPA) was used to detect potential deletion and duplication of the DMD gene, and the DNA products were sequenced on a Genetic Analyzer 3130 sequencer. Haplotype analysis was performed using four short tandem repeat polymorphism loci (44C/A, 45C/A, 49C/A and 63C/A) of the DMD gene for the family. A same deletional mutation (Del 48-50) of the DMD gene was detected in the proband and fetus, but not in their mother. The proband and fetus have inherited the same haplotype of the DMD gene from their mother. The fetus was predicted to be affected by the disease. Above findings suggested that the mother was very likely to have a germline mosaicism for the DMD gene mutation. For the de novo DMD mutation, although genetic analysis of peripheral blood DNA has indicated that the proband's mother was not a carrier, germline mosaicism could still not be ruled out, and prenatal gene diagnosis should be provided for subsequent pregnancies.

Correlation analysis between cardiac damage and genotype in Duchenne muscular dystrophy

Objective To explore the evolution of Duchenne muscular dystrophy (DMD) patients with cardiac damage. Methods Clinical data of 144 DMD patients who were clearly diagnosed by gene detection were collected and analyzed. According to the results of ultrasonic cardiography, they were divided into cardiac involvement group (N = 50) and non-involvement group (N = 94). The correlation between genotypes and cardiac damage was analyzed. Results Compared with non-involvement group, cardiac involvement group had larger atrium and ventricle ( P < 0.01), thicker posterior wall of left ventricle and interventricular septum ( P = 0.031, 0.001), as well as lower left ventricular ejection fraction ( P = 0.034). In addition, the mutation rates of DMD gene in exon 3 ( P = 0.047), exon 4 ( P = 0.047), exon 21 ( P = 0.047), exon 22 ( P = 0.040) and exon 53 ( P = 0.033) were increased significantly, indicating that mutations had a correlation with cardiac damage. Conclusions The main performance of DMD cardiac damage is dilated cardiomyopathy. It has more possibility to cause cardiac damage when DMD gene mutation is closer to the end of 5'-terminal. DOI: 10.3969/j.issn.1672-6731.2015.06.007

Genetic testing and prenatal diagnosis for eight families affected with Duchenne muscular dystrophy

To optimize the methods for genetic detection and prenatal diagnosis of Duchenne muscular dystrophy (DMD). Denaturing high-performance liquid chromatography (DHPLC), multiplex PCR (mPCR), sequencing and other molecular techniques were used in combination for molecular diagnosis of 8 cases diagnosed as DMD. Among the 8 cases, 4 have carried large deletions, 3 have point mutations, among which 6 were of de novo type. Prenatal diagnosis were offered for 5 families, the results showed that none of the fetuses had carried large deletions or point mutations. The pregnancies had continued and healthy babies were born. Combined use of short tandem repeat, DHPLC, mPCR and sequencing can improve the detection of DMD gene mutations. By establishing and optimizing genetic and prenatal diagnostic methods, accurate genetic counseling can be provided for families affected with DMD.

Natural history of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is X-linked recessive hereditary disease. DMD gene mutations result in dystrophin deficiency, which causes not only muscle movement disorders but also scoliosis, cognitive dysfunction, urinary tract diseases, respiratory diseases and heart diseases. Most patients die in early adult for respiratory and circulatory failure. Early multidisciplinary therapies will significantly delay disease progression and improve patients' quality of life. However, DMD diagnosis and treatment exist significantly time delay now. In this study, we review the natural history of DMD, including motor, cognitive, respiratory and heart function, for improving DMD early recognition, diagnosis and treatment, so as to benefit DMD patients. DOI: 10.3969/j.issn.1672-6731.2015.05.004