A female case report of LGMD2B with compound heterozygous mutations of the DYSF gene and asymptomatic mutation of the X-linked DMD gene

We report the case of a 31-year-old Chinese woman with a chief complaint of weakness in the lower limbs, which was diagnosed as limb-girdle muscular dystrophy 2B (LGMD2B) with compound heterozygous mutations of the DYSF gene. Meanwhile, this woman is an asymptomatic carrier with the mutation of the X-linked DMD gene. The electromyography, muscle MRI, and muscle biopsy indicated a chronic myogenic injury with dysferlin deletion. As a result of genetic testing, compound heterozygous G-to-T base substitution at position 5,497 in exon 49 of the DYSF gene, leading to a codon change from glutamic acid to termination codon at position 1,833, and a heterozygous C-to-G base change at position 4,638 + 8 in intron 42 of the DYSF gene with a consequence of splice, which has never been reported, were identified as candidate causative mutations. Unfortunately, DMD gene mutation c.3921+12A>G of the DMD gene on the X chromosome was also found in this patient. Finally, the patient was diagnosed as LGMD2B clinically and genetically. In the previous 2 years, the patient's lower limb weakness became slightly worse, resulting in even the total distance walked than before. Fortunately, during the follow-up, her son had not shown slowness or limitation of movement. Genetic testing by next-generation sequencing confirmed the final diagnosis of LGMD2B, and we identified the novel compound heterozygous variants in the DYSF gene, which is of great significance to the accurate diagnosis of genetically coded diseases. Much attention needs to be paid in clinics toward hereditary neuromuscular diseases with multiple pathogenic gene mutations. Genetic counseling and clinical follow-up should be the priorities in future, and promising treatments are also worth exploring.

Comprehensive Molecular Analysis of DMD Gene Increases the Diagnostic Value of Dystrophinopathies: A Pilot Study in a Southern Italy Cohort of Patients

Duchenne/Becker muscular dystrophy (DMD/BMD) is an X-linked neuromuscular disease due to pathogenic sequence variations in the dystrophin (DMD) gene, one of the largest human genes. More than 70% of DMD gene defects result from genomic rearrangements principally leading to large deletions, while the remaining are small nucleotide variants, including nonsense and missense variants, small insertions/deletions or splicing alterations. Considering the large size of the gene and the wide mutational spectrum, the comprehensive molecular diagnosis of DMD/BMD is complex and may require several laboratory methods, thus increasing the time and costs of the analysis. In an attempt to simplify DMD/BMD molecular diagnosis workflow, we tested an NGS method suitable for the detection of all the different types of genomic variations that may affect the DMD gene. Forty previously analyzed patients were enrolled in this study and re-analyzed using the next generation sequencing (NGS)-based single-step procedure. The NGS results were compared with those from multiplex ligation-dependent probe amplification (MLPA)/multiplex PCR and/or Sanger sequencing. Most of the previously identified deleted/duplicated exons and point mutations were confirmed by NGS and 1 more pathogenic point mutation (a nonsense variant) was identified. Our results show that this NGS-based strategy overcomes limitations of traditionally used methods and is easily transferable to routine diagnostic procedures, thereby increasing the diagnostic power of DMD molecular analysis.

Cardiac Phenotype-Genotype Associations in DMD/BMD: A Meta-Analysis and Systematic Review

Cardiac involvement of Duchenne and Becker muscular dystrophies (DMD/BMD) is the most common cause of fatal outcomes. It is still unclear whether some DMD/BMD gene mutations might be predictive of cardiac involvement. In this study, we provide a comprehensive overview on genotypes of cardiac disease in DMD/BMD. We systematically searched the PubMed/Medline, EMBASE and Cochrane electronic databases. Search results were filtered to include only human studies, English language and all dates up to August 2019. We summarized and extensively reviewed all studies that passed the selection criteria and performed a meta-analysis on key genotype parameters of cardiac disease in DMD/BMD. Of 3450 articles scanned, we included 18 studies from 9 regions in the meta-analysis. The pooled studies included 2661 DMD/BMD patients and 1324 DMD/BMD patients with cardiac disease. The most common mutation type was exon deletion, with a pooled frequency of 90% (P < 0.01). In DMD/BMD patients with cardiac dysfunction, a higher frequency of involvement of exons 45 and 46 was found in DMD/BMD patients with cardiac dysfunction. This might be predictive of cardiac involvement in patients with DMD/BMD.

Patterns of growth in ambulatory males with Duchenne muscular dystrophy

OBJECTIVE

To provide weight-for-age, height-for-age, and body mass index-for-age growth reference standards for ambulatory, steroid-naïve males, ages 2-12 years, with Duchenne muscular dystrophy (DMD) and to compare these growth curves to the 2000 Centers for Disease Control and Prevention growth charts for boys, which serve as references of physical size and growth for the general male pediatric population in the US.

STUDY DESIGN

Through a multi-state population-based surveillance of individuals with muscular dystrophy, a total of 1877 weight and 1544 height measurements ascertained during 1985-2010 from 513 males with DMD were obtained retrospectively from medical record review. Cases were classified as DMD if loss of ambulation occurred before the 12th birthday or, if younger than 12 years and still ambulating, the earliest symptoms of dystrophinopathy occurred before the 6th birthday. Each growth chart was constructed using 5 percentiles: 10th, 25th, 50th, 75th, and 90th. Smoothing procedures were applied in 2 stages to the irregular plots of the empirical percentile values.

RESULTS

A set of growth curves, derived from a large cohort of male youth with DMD, are presented. These curves demonstrate that DMD males are shorter and tend to the extremes of weight and body mass index compared with the general male pediatric population in the US.

CONCLUSION

Charts representing the pattern of growth in ambulatory, steroid-naïve males with DMD can facilitate monitoring of growth and early detection of unusual growth patterns. Use of these growth standards also will assist in monitoring responses to corticosteroid treatment.