Matrilineal analysis of mutations in the DMD gene in a multigenerational South Indian cohort using DMD gene panel sequencing

Identification and analysis of differentially expressed lncRNAs and their ceRNA networks in DMD/mdx primary myoblasts

This study explored the significance of long non-coding RNAs (lncRNAs), particularly their role in maintaining dystrophin protein stability and regulating myocyte proliferation and differentiation. The investigation focused on DMD/mdx mouse skeletal muscle primary myoblasts, aiming to identify lncRNAs potential as biomarkers and therapeutic targets for Duchenne muscular dystrophy (DMD). Utilizing CLC Genomics Workbench software, 554 differentially expressed lncRNAs were identified in DMD/mdx mice compared to wild-type (WT) control. Among them, 373 were upregulated, and 181 were downregulated. The study highlighted specific lncRNAs (e.g., 5930430L01Rik, Gm10143, LncRNA1490, LncRNA580) and their potential regulatory roles in DMD key genes like IGF1, FN1, TNNI1, and MYOD1. By predicting miRNA and their connections with lncRNA and mRNA (ceRNA network) using tools such as miRNet, miRSYSTEM and miRCARTA, the study revealed potential indirect regulation of Dystrophin, IGF1R and UTRN genes by identified lncRNAs (e.g. 2310001H17Rik-203, C130073E24Rik-202, LncRNA2767, 5930430L01Rik and LncRNA580). These findings suggest that the identified lncRNAs may play crucial roles in the development and progression of DMD through their regulatory influence on key gene expression, providing valuable insights for potential therapeutic interventions.

The cryptic complex rearrangements involving the DMD gene: etiologic clues about phenotypical differences revealed by optical genome mapping

BACKGROUND

Deletion or duplication in the DMD gene is one of the most common causes of Duchenne and Becker muscular dystrophy (DMD/BMD). However, the pathogenicity of complex rearrangements involving DMD, especially segmental duplications with unknown breakpoints, is not well understood. This study aimed to evaluate the structure, pattern, and potential impact of rearrangements involving DMD duplication.

METHODS

Two families with DMD segmental duplications exhibiting phenotypical differences were recruited. Optical genome mapping (OGM) was used to explore the cryptic pattern of the rearrangements. Breakpoints were validated using long-range polymerase chain reaction combined with next-generation sequencing and Sanger sequencing.

RESULTS

A multi-copy duplication involving exons 64-79 of DMD was identified in Family A without obvious clinical symptoms. Family B exhibited typical DMD neuromuscular manifestations and presented a duplication involving exons 10-13 of DMD. The rearrangement in Family A involved complex in-cis tandem repeats shown by OGM but retained a complete copy (reading frame) of DMD inferred from breakpoint validation. A reversed insertion with a segmental repeat was identified in Family B by OGM, which was predicted to disrupt the normal structure and reading frame of DMD after confirming the breakpoints.

CONCLUSIONS

Validating breakpoint and rearrangement pattern is crucial for the functional annotation and pathogenic classification of genomic structural variations. OGM provides valuable insights into etiological analysis of DMD/BMD and enhances our understanding for cryptic effects of complex rearrangements.

Generation of two induced pluripotent stem cell (iPSC) lines from patients with Duchenne muscular dystrophy (IGIBi006-A and IGIBi008-A) carrying exonic deletions in the dystrophin gene

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder with defect in dystrophin gene that shows features of degeneration of muscle tissue at an early age. Here, we describe iPSC lines generated from LCL of two patients of Indian origin carrying 46-48 and 49-50 exons deletions in DMD. The resulting iPSC lines IGIBi006-A and IGIBi008-A showed all the characteristic features of pluripotency, differentiated into cells of three germ layers in vitro and have no major genetic alterations due to reprogramming process. These lines can serve as a useful cell model for studying disease pathogenesis and will aid in precision therapy.