Large Duchenne Muscular Dystrophy Research Articles

Tissue- and cell-specific whole-transcriptome meta-analysis from brain and retina reveals differential expression of dystrophin complexes and new dystrophin spliced isoforms.

The large DMD gene encodes a group of dystrophin proteins in brain and retina, produced from multiple promoters and alternative splicing events. Dystrophins are core components of different scaffolding complexes in distinct cell types. Their absence may thus alter several cellular pathways, which might explain the heterogeneous genotype-phenotype relationships underlying central comorbidities in Duchenne muscular dystrophy (DMD). However, the cell-specific expression of dystrophins and associated proteins (DAPs) is still largely unknown. The present study provides a first RNA-Seq-based reference showing tissue- and cell-specific differential expression of dystrophins, splice variants and DAPs in mouse brain and retina. We report that a cell type may express several dystrophin complexes, perhaps due to expression in separate cell subdomains and/or subpopulations, some of which with differential expression at different maturation stages. We also identified new splicing events in addition to the common exon-skipping events. These include a new exon within intron 51 (E51b) in frame with the flanking exons in retina, as well as inclusions of intronic sequences with stop codons leading to the presence of transcripts with elongated exons 40 and/or 41 (E40e, E41e) in both retina and brain. PCR validations revealed that the new exons may affect several dystrophins. Moreover, immunoblot experiments using a combination of specific antibodies and dystrophin-deficient mice unveiled that the transcripts with stop codons are translated into truncated proteins lacking their C-terminus, which we called N-Dp427 and N-Dp260. This study thus uncovers a range of new findings underlying the complex neurobiology of DMD.

Respiratory Function and Sleep Disordered Breathing in Pediatric Duchenne Muscular Dystrophy.

The decline of respiratory function in Duchenne muscular dystrophy (DMD) is associated with sleep disordered breathing (SDB) and alteration of nocturnal gas exchange, first manifesting as nocturnal hypoventilation (NH). However, the correlation between the pulmonary function measured by spirometry (PFT) and the onset of SDB with or without NH is unclear. The aims of this study are to identify the prevalence and features of SDB and to investigate the relationship between lung function determined by forced vital capacity (FVC) and sleep abnormalities in a large pediatric DMD population. This was a retrospective, single-center cohort study. FVC% predicted (FVC%) was calculated using predicted equations from the Global Lung Function Initiative. NH was defined by transcutaneous (tc) CO2 >50 mm Hg for >25% of total sleep time (TST), borderline NH by a mean tcCO2 between 45 and 50 mm Hg or tcCO2>50 mm Hg for ≤25% of TST, and clinically meaningful obstructive sleep apnea (OSA) by obstructive apnea-hypopnea index >5. The sensitivity, specificity, and positive and negative predictive values of FVC < 50% to indicate the presence of nocturnal hypoventilation were calculated. One hundred thirty-four patients underwent 284 sleep studies and 1222 PFT. The mean (SD) age at the first and the last sleep study was 12.9 (2.7) and 14.3 (2.6) years, respectively. Borderline NH (n = 31) was detected in both ambulant and early-nonambulant participants, while 100% of NH cases (n = 14) were nonambulant. NH was detected in 4 of the 14 patients despite an FVC >50%. Seventeen of the 26 patients with OSA presented with concomitant NH or borderline NH. FVC <50% was associated with NH indicating a sensitivity and specificity of 73% and 86%, respectively. Positive and negative predictive values were 32% and 97%, respectively. PFT showed a nonlinear, sudden FVC% decline in 18% of cases. FVC% <50 was associated with NH in close to a third of patients. CO2 elevation can be associated with obstructive/pseudo-obstructive events and was also observed in early nonambulant cases or in the presence of FVC >50%. These results are relevant for the clinical management of SDB.

Comparison of dystrophin expression following gene editing and gene replacement in an aged preclinical DMD animal model

Gene editing has shown promise for correcting or bypassing dystrophin mutations in Duchenne muscular dystrophy (DMD). However, preclinical studies have focused on young animals with limited muscle fibrosis and wasting, thereby favoring muscle transduction, myonuclear editing, and prevention of disease progression. Here, we explore muscle-specific dystrophin gene editing following intramuscular delivery of AAV6:CK8e-CRISPR/SaCas9 in 3- and 8-year-old dystrophic CXMD dogs and provide a qualitative comparison to AAV6:CK8e-micro-dystrophin gene replacement at 6weeks post-treatment. Gene editing restored the dystrophin reading frame in ∼1.3% of genomes and in up to 4.0% of dystrophin transcripts following excision of a 105-kb mutation containing region spanning exons 6-8. However, resulting dystrophin expression levels and effects on muscle pathology were greater with the use of micro-dystrophin gene transfer. This study demonstrates that our muscle-specific multi-exon deletion strategy can correct a frequently mutated region of the dystrophin gene in an aged large animal DMD model, but underscores that further enhancements are required to reach efficiencies comparable to AAV micro-dystrophin. Our observations also indicate that treatment efficacy and state of muscle pathology at the time of intervention are linked, suggesting the need for additional methodological optimizations related to age and disease progression to achieve relevant clinical translation of CRISPR-based therapies to all DMD patients.

Novel Intronic Mutations Introduce Pseudoexons in DMD That Cause Muscular Dystrophy in Patients

Background: Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are two subtypes of muscular dystrophy diseases caused by pathogenic mutations in the DMD gene. Until now, more than 4,600 disease-causing mutations in DMD have been reported. However, only 33 mutations were deep intronic, cases with this type of mutations were limited.Methods: In this study, we used a combination of complementary DNA (cDNA) and target DNA sequencing analysis in addition to conventional whole-exome sequencing (WES).Results: Three novel hemizygous mutations IVS11 + 17811C > G (c.1331 + 17811C > G), IVS21 + 3252A > G (c.2803 + 3252A > G) and IVS40 + 362A > G (c.5739 + 362A > G) were identified in DMD patients, while a reported hemizygous mutation IVS62-285A > G (c.9225-285A > G) was found in the BMD patient. These DMD mutations lead to pseudoexon insertions, causing the generation of truncated and dysfunctional dystrophin.Conclusion: This study defines three novel and one reported intronic mutations, which can result in DMD/BMD. We also emphasize the need to combine WES and cDNA-based methods to detect the variant in the very large DMD gene in which the mutational spectrum is complex.

Risk Factors for Cardiac and Non-cardiac Causes of Death in Males with Duchenne Muscular Dystrophy.

As survival and neuromuscular function in Duchenne muscular dystrophy (DMD) have improved with glucocorticoid (GC) therapy and ventilatory support, cardiac deaths are increasing. Little is known about risk factors for cardiac and non-cardiac causes of death in DMD. A multi-center retrospective cohort study of 408 males with DMD, followed from January 1, 2005 to December 31, 2015, was conducted to identify risk factors for death. Those dying of cardiac causes were compared to those dying of non-cardiac causes and to those alive at study end. There were 29 (7.1%) deaths at a median age of 19.5 (IQR: 16.9-24.6) years; 8 (27.6%) cardiac, and 21 non-cardiac. Those living were younger [14.9 (IQR: 11.0-19.1) years] than those dying of cardiac [18 (IQR 15.5-24)years, p = 0.03] and non-cardiac [19 (IQR: 16.5-23)years, p = 0.002] causes. GC use was lower for those dying of cardiac causes compared to those living [2/8 (25%) vs. 304/378 (80.4%), p = 0.001]. Last ejection fraction prior to death/study end was lower for those dying of cardiac causes compared to those living (37.5% ± 12.8 vs. 54.5% ± 10.8, p = 0.01) but not compared to those dying of non-cardiac causes (37.5% ± 12.8 vs. 41.2% ± 19.3, p = 0.58). In a large DMD cohort, approximately 30% of deaths were cardiac. Lack of GC use was associated with cardiac causes of death, while systolic dysfunction was associated with death from any cause. Further work is needed to ensure guideline adherence and to define optimal management of systolic dysfunction in males with DMD with hopes of extending survival.

Normal and altered pre-mRNA processing in the DMD gene.

Splicing of pre-mRNA is a crucial regulatory stage in the pathway of gene expression controlled by multiple post- and co-transcriptional mechanisms. The large Duchenne muscular dystrophy gene encoding the protein dystrophin provides a striking example of the complexity of human pre-mRNAs. In this review, we summarize the current state of knowledge about canonical and non-canonical splicing in the DMD pre-mRNA, with a focus on mechanisms that take place in the full-length transcript isoform expressed in human skeletal muscle. In particular, we highlight recent work demonstrating that multi-step events are required for long DMD intron removal. The role of temporary intron retention in the occurrence of alternative splicing events is also discussed. Even though the proportion of splicing mutations is lower than reported in other genes, a great diversity of splicing defects linked to point mutations, but also large genomic rearrangements are observed in the DMD gene. We provide an overview of the molecular mechanisms underlying aberrant splicing in patients with Duchenne or Becker muscular dystrophy, and we also detail how alternative splicing can serve as a disease modifier in patients by changing the outcome of the primary defect.

Relationship of Right Ventricular Size and Function with Respiratory Status in Duchenne Muscular Dystrophy.

The relationship between pulmonary function and right ventricle (RV) in Duchenne muscular dystrophy (DMD) has not been evaluated. Using cardiac magnetic resonance (CMR), we describe the relationship of RV size and function with spirometry in a DMD cohort. Fifty-seven boys undergoing CMR and pulmonary function testing within 1month at a single center (2013-2015) were enrolled. Comparisons of RV ejection fraction (RVEF) and end-diastolic volume index (RVEDVI) were made across categories of percent forced vital capacity (FVC%), and relationships were assessed. Mean age was 15.5±3.5years. Spirometry and CMR were performed within 3.9±4.1days. Median FVC% was 92.0% (67.5-116.5%). Twenty-three (40%) patients had abnormal FVC% (<80%) of which 13 (57%) had mild (FVC% 60-79%), 6 (26%) had moderate (FVC% 40-59%), and 4 (17%) had severe (FVC <40%) reductions. Mean RVEF was 58.3±3.7%. Patients with abnormal FVC% were older and had lower RVEF and RVEDVI. Both RVEF and RVEDVI were significantly associated with FVC% (r=0.31, p=0.02 and r=0.39, p=0.003, respectively). In a large DMD cohort, RVEF and RVEDVI were related to FVC%. Worsening respiratory status may guide monitoring of cardiac function in these patients.

Fast detection of deletion breakpoints using quantitative PCR.

The routine detection of large and medium copy number variants (CNVs) is well established. Hemizygotic deletions or duplications in the large Duchenne muscular dystrophy DMD gene responsible for Duchenne and Becker muscular dystrophies are routinely identified using multiple ligation probe amplification and array-based comparative genomic hybridization. These methods only map deleted or duplicated exons, without providing the exact location of breakpoints. Commonly used methods for the detection of CNV breakpoints include long-range PCR and primer walking, their success being limited by the deletion size, GC content and presence of DNA repeats. Here, we present a strategy for detecting the breakpoints of medium and large CNVs regardless of their size. The hemizygous deletion of exons 45-50 in the DMD gene and the large autosomal heterozygous PARK2 deletion were used to demonstrate the workflow that relies on real-time quantitative PCR to narrow down the deletion region and Sanger sequencing for breakpoint confirmation. The strategy is fast, reliable and cost-efficient, making it amenable to widespread use in genetic laboratories.

Comparison of right and left ventricular function and size in Duchenne muscular dystrophy

IntroductionRight ventricular (RV) size and function in Duchenne muscular dystrophy (DMD) have not been well described. Using cardiac magnetic resonance (CMR) imaging we describe the relationship of RV and left ventricular (LV) size and function in a large DMD cohort. MethodsLatest CMR scans of 272 patients consecutively seen at a single tertiary referral center (2011–2014) with skeletal muscle biopsy confirmed DMD were included. 1.5 and 3 Tesla CMR scanners were used. Biventricular ejection fraction (EF), end-diastolic volume index (EDVI), mass and mass index were compared across categories of LVEF. ResultsMean age was 13.5±4.9 years. 71% had normal (≥55%) LVEF while mild (EF 45–54%), moderate (EF 30–44%), and severe LV dysfunction (EF <30%) was present in 20%, 6% and 3% respectively. The correlation between RVEF and LVEF was weak. Even in patients with severe LV dysfunction, RVEF (49.7%±12.9%) was relatively preserved. There were no significant differences in RVEDVI and RV mass index across categories of LV function. ConclusionIn a large DMD cohort, RVEF was relatively preserved and RV size was preserved across categories of LV dysfunction.

Myocardial fibrosis burden predicts left ventricular ejection fraction and is associated with age and steroid treatment duration in duchenne muscular dystrophy.

BackgroundPatients with Duchenne muscular dystrophy exhibit progressive cardiac and skeletal muscle dysfunction. Based on prior data, cardiac dysfunction in Duchenne muscular dystrophy patients may be influenced by myocardial fibrosis and steroid therapy. We examined the longitudinal relationship of myocardial fibrosis and ventricular dysfunction using cardiac magnetic resonance in a large Duchenne muscular dystrophy cohort.Methods and ResultsWe reviewed 465 serial cardiac magnetic resonance studies (98 Duchenne muscular dystrophy patients with ≥4 cardiac magnetic resonance studies) for left ventricular ejection fraction (LVEF) and presence of late gadolinium enhancement (LGE), a marker for myocardial fibrosis. LVEF was modeled by examining LGE status, myocardial fibrosis burden (as assessed by the number of LGE‐positive left ventricular segments), patient age, and steroid treatment duration. An age‐only model demonstrated that LVEF declined 0.58±0.10% per year. In patients with both LGE‐negative and LGE‐positive studies (n=51), LVEF did not decline significantly over time if LGE was absent but declined 2.2±0.31% per year when LGE was present. Univariate modeling showed significant associations between LVEF and steroid treatment duration, presence of LGE, and number of LGE‐positive left ventricular segments; multivariate modeling showed that LVEF declined by 0.93±0.09% for each LGE‐positive left ventricular segment, whereas age and steroid treatment duration were not significant. The number of LGE‐positive left ventricular segments increased with age, and longer steroid treatment duration was associated with lower age‐related increases.ConclusionProgressive myocardial fibrosis, as detected by LGE, was strongly correlated with the LVEF decline in Duchenne muscular dystrophy patients. Longer steroid treatment duration was associated with a lower age‐related increase in myocardial fibrosis burden.

Abstract 12450: Myocardial Fibrosis Burden Predicts Left Ventricular Ejection Fraction and is Modified by Age and Steroid Treatment Duration in Duchenne Muscular Dystrophy

Background: Patients with Duchenne muscular dystrophy (DMD) typically exhibit progressive cardiac and skeletal muscle dysfunction, and are commonly treated with corticosteroids to prolong ambulation. Myocardial fibrosis and steroid treatment may modulate the progression of cardiac dysfunction in DMD patients. We aimed to longitudinally characterize the impact of myocardial fibrosis and steroid treatment on the progression of cardiac dysfunction using cardiac magnetic resonance (CMR) in a large DMD cohort. Methods: Serial CMR studies performed on DMD patients were reviewed for LVEF and late gadolinium enhancement (LGE) status, a marker for myocardial fibrosis. LVEF was modeled by examining effects of patient age, steroid treatment duration, LGE status, and myocardial fibrosis burden, as assessed by the number of LGE positive (LGE+) LV segments. Results: We analyzed 469 CMR studies from 99 DMD patients with ≥4 CMRs. Patient age at time of CMR ranged from 6.6 to 29.4 (median 12.3) years. There were 146 (31.1%) LGE+ studies and 59 studies (12.6%) that demonstrated depressed LVEF (LVEF&lt;55%). An age-only model demonstrated that LVEF declined 0.58±0.10%/yr (p&lt;0.0001, r 2 =0.067). Univariate modeling showed significant associations between LVEF and steroid treatment duration, presence of LGE, and number of LGE+ LV segments; multivariate modeling showed that LVEF declined by 0.93±0.09% for each LGE+ LV segment (p&lt;0.0001, r 2 =0.171), while age and steroid treatment duration were no longer significant. The number of LGE+ LV segments increased with age by 1.2 segments/year (95% confidence interval 1.1-1.2), and steroid treatment partially mitigated this increase (interaction term β=-0.01±0.005, p=0.010). Conclusions: Progressive myocardial fibrosis, as imaged by LGE on CMR, is a strong marker for the decline in LVEF in DMD patients. Steroid treatment partially attenuates the age-related increase in myocardial fibrosis burden.

G.P.171: Age-specific prevalence of osteoporosis and frequency of poor bone health indices in Duchenne Muscular Dystrophy

Osteoporosis is a major problem in Duchenne Muscular Dystrophy (DMD) patients due to long term glucocorticoid (GC) therapy and immobility. There is neither age-specific prevalence data nor consensus on management of osteoporosis in DMD. To determine age-specific prevalence of osteoporosis and frequency of poor bone health indices in pediatric DMD patients. Methods: We retrospectively examined age-specific prevalence of osteoporosis and poor bone health indices in GC-treated DMD patients seen between January 2005 and July 2012 at Cincinnati Children's Hospital. Outcomes of interest were fractures (total, vertebral, long bone), and low age- and height-adjusted <i>z</i>-scores (<−2) of total body (TB) and lumbar spine (LS) bone mineral density (BMD) and content (BMC) by DXA. We studied 408 patients with 1415 clinical visits (median 3 visits per patient). Ages ranged from 3.0 to 19.3 (mean 10.6 ±3.7) years at last follow up. By the last visit: 85 (20.8%) were on bisphosphonates, 293 (71.8%) were ambulatory, 339 (83.1%) were prepubertal, and mean daily GC duration was 4.4 ±2.8years. DMD patients acquired vertebral and long bone fractures at a young age. Fracture prevalence increased with age. Prevalence of total fractures was 16.5%, 37.4% and 83.3% at ages 5, 10 and 18years respectively. Prevalence of vertebral fractures was 4.4%, 19.1% and 58.3% at the same ages. Prevalence of osteoporosis as defined by the ISCD 2013 was similar (4.4%, 20.9% and 58.3%). Frequency of low BMD and BMC <i>z</i>-scores also increased with age, and varied with site of measurement. Osteoporosis is frequent in DMD patients from a young age. Our study is the first to examine age-specific prevalence of osteoporosis and frequency of poor bone health indices throughout the pediatric age span in a large DMD cohort. These data also highlight the complexity of bone health measures, and the urgent need to improve detection, prevention and treatment of osteoporosis in DMD.

T.P.16 Restoring the reading frame in large DMD duplication mutations results in dystrophin expression in vivo

Abstract Antisense oligonucleotide (AON) therapy has been shown to be an effective treatment for restoring dystrophin expression in mdx mice and Duchenne muscular dystrophy (DMD) patients with out-of-frame mutations. However, to date, limited exon skipping studies have been conducted in DMD patients with large out-of-frame duplication mutations. Whilst exon-skipping one or two exons is a highly efficient process in cell culture, efficiency falls when targeting multiple exons, thus producing little of the desired end product. Therefore, we sought to understand the expression and function of large DMD duplication proteins when only two exons are removed in order to restore the reading frame. We constructed large “in-frame” DMD duplication mutation plasmids and evaluated their expression in vivo. Two out-of-frame DMD duplication mutations (dup ex22–29 and dup ex18–30) were modified to express in-frame human dystrophin transcripts (del ex21–22 dup ex23–29 and del ex17–18 dup ex19–30). In addition, an original “in-frame” DMD duplication mutation (dup ex3–25) was cloned to determine if over expression of the duplicated transcript would result in protein expression. Plasmids were electroporated into TA muscles of mdx mice, and human dystrophin expression was evaluated 7 days later. Human dystrophin expression was detected at the sarcolemma for all the constructs, confirming the duplicated proteins were stable. In addition, all three proteins recruited the nNOs protein. Whilst this study indicates DMD patients with out-of-frame duplication mutations may be suitable candidates for AON therapy, further work to analyse the protective potential of restored in-frame duplication mutations is necessary. We are currently investigating DMD duplication protein function through the exclusion of Evans blue dye post treadmill exercises. In addition, plasmids will be administrated into neonatal mdx mice to assess the ability of the constructs to prevent muscle fibre degeneration.

Comparison of Magnetic Resonance Feature Tracking for Strain Calculation With Harmonic Phase Imaging Analysis

To compare a steady-state free precession cine sequence-based technique (feature tracking [FT]) to tagged harmonic phase (HARP) analysis for peak average circumferential myocardial strain (epsilon(cc)) analysis in a large and heterogeneous population of boys with Duchenne muscular dystrophy (DMD). Current epsilon(cc) assessment techniques require cardiac magnetic resonance-tagged imaging sequences, and their analysis is complex. The FT method can readily be performed on standard cine (steady-state free precession) sequences. We compared mid-left ventricular whole-slice epsilon(cc) by the 2 techniques in 191 DMD patients grouped according to age and severity of cardiac dysfunction: group B: DMD patients 10 years and younger with normal ejection fraction (EF); group C: DMD patients older than 10 years with normal EF; group D: DMD patients older than 10 years with reduced EF but negative myocardial delayed enhancement (MDE); group E: DMD patients older than 10 years with reduced EF and positive MDE; and group A: 42 control subjects. Retrospective, offline analysis was performed on matched tagged and steady-state free precession slices. For the entire study population (N = 233), mean FT epsilon(cc) values (-13.3 +/- 3.8%) were highly correlated with HARP epsilon(cc) values (-13.6 +/- 3.4%), with a Pearson correlation coefficient of 0.899. The mean epsilon(cc) of DMD patients determined by HARP (-12.52 +/- 2.69%) and FT (-12.16 +/- 3.12%) was not significantly different (p = NS). Similarly, the mean epsilon(cc) of the control subjects by determined HARP (-18.85 +/- 1.86) and FT (-18.81 +/- 1.83) was not significantly different (p = NS). Excellent correlation between the 2 methods was found among subgroups A through E, except there was no significant difference in strain between groups B and C with FT analysis. FT-based assessment of epsilon(cc) correlates highly with epsilon(cc) derived from tagged images in a large DMD patient population with a wide range of cardiac dysfunction and can be performed without additional imaging.

M.P.1.04 Comparison of disease-causing mutations in Duchenne muscular dystrophy from the Cooperative International Neuromuscular Research Group with two large DMD mutation databases

Objectives: Multiple dystrophin mutation types cause Duchenne muscular dystrophy (DMD). The recent development of DMD patient registries accentuates the need for global harmonization of mutation data collection. More consistent characterization of disease-causing mutations would enhance analyses of the distribution of such mutations from around the world. We investigated the mutations reported in DMD patients studied by the large international academic research group, the Cooperative International Neuromuscular Research Group (CINRG).

Exon skipping and Duchenne muscular dystrophy: Hope, hype and how feasible?

Duchenne muscular dystrophy (DMD), the most common and serious form of childhood muscle wasting is generally caused by protein-truncating mutations in the large DMD gene. Specific removal of an exon from a defective DMD gene transcript has the potential to allow synthesis of a semi-functional dystrophin, thereby reducing the severity and presumably progression of muscle wasting. The efficacy of this treatment will vary greatly between the different mutations that preclude the synthesis of a functional dystrophin. Restoration of the reading frame from a large multi-exon genomic deletion, typically greater than 36 exons, may lead to synthesis of a protein with only partial function and limited clinical benefit, whereas excising a nonsense mutation in a redundant exon should generate a near normal dystrophin. A clinical trial has recently confirmed proof-of-principle that exclusion of Exon 51 from human dystrophin mRNAs, carrying frame-shifting deletions adjacent to this exon, results in dystrophin expression. No major side-effects after local administration of the antisense oligomer were reported. Additional trials are underway, targeting the same exon but using an oligomer of different backbone chemistry. If functional dystrophin synthesis is demonstrated, and safety issues are addressed, subsequent trials will involve systemic delivery. Great challenges are ahead, some technical; establishing an effective delivery regimen, some ethical; choosing subsequent targets for therapy, and others of an administrative and regulatory nature.

G.P.12.11 Do revertants increase with age in Duchenne muscular dystrophy boys?

Background: Duchenne muscular dystrophy (DMD) diagnosis is confirmed by the absence of dystrophin in muscle biopsies. However, the presence of dystrophin positive fibres (revertants) is reported in 50% of DMD diagnostic biopsies. Dystrophin traces are also frequently reported but their significance is unclear. Revertant fibres are present in the mdx mice, with similar percentages and increase with age. We are involved in a phase I/II study in DMD using antisense oligonucleotides. As the presence of dystrophin traces or the possible accumulation of revertants might affect the endpoint of our study, we have characterised further these two phenomena in a large DMD cohort.

Predictive factors for the development of scoliosis in Duchenne muscular dystrophy

Objective Scoliosis is a frequent complication (68–90%) of Duchenne muscular dystrophy (DMD). Prevention of limb deformities, rehabilitation in knee–ankle–foot-orthoses (KAFOs) and glucocorticoids prolong walking and standing, and might reduce scoliosis. We evaluated possible predictive factors for scoliosis development in a large DMD population. Methods Case notes of 123 DMD boys, ⩾17 years, followed at our centre between 1992 and 2002 were reviewed. Univariate analysis was used to relate two outcome measures (age at onset of scoliosis and severity at 17 years) with (i) glucocorticoids treatment; (ii) ages at (a) loss of independent ambulation, (b) rehabilitation into KAFOs, (c) loss of standing, (iii) forced vital capacity (FVC) (%) between 11 and 12 years and (iv) lower limb contractures. Results In total, 37/123 boys (30%) received intermittent prednisolone (0.75 mg/kg/day, 10 day/month) for a median 1-year (2 months–9 years), starting between 7.7 and 12.4 years (mean 9.5). About 96/123 (78%) were rehabilitated into KAFOs at 10.2±1.6 years. Age at loss of ambulation in KAFOs was 12.3±1.9 years and at loss of standing 12.8±2.1 years. About 95/123 (77%) boys developed scoliosis (Cobb angle >30°). Mean age±S.D. at scoliosis onset was 12.7±1.6 years. Forty-three boys (35%) had scoliosis surgery by 15±1.2 years. Later age at loss of ambulation ( p<0.0001) and longer duration of prednisolone treatment ( p=0.01) related to later scoliosis onset. Ages at loss of ambulation and standing were inversely related to scoliosis severity at 17 years ( p<0.005). Hip asymmetry and %FVC at 11–12 years were directly related to scoliosis severity ( p=0.02). Conclusions Our data indicate a significant association between prolonged ambulation and a reduced risk of scoliosis development. Glucocorticoid administration, in our series, appear to be associated with a later onset of scoliosis, but did not alter the severity at 17 years, probably reflecting the shorter overall glucocorticoid exposure in this population.