Yanli Zhu

Bio: Yanli Zhu is an academic researcher from Boston Children's Hospital. The author has contributed to research in topics: Duchenne muscular dystrophy & Muscular dystrophy. The author has an hindex of 1, co-authored 1 publications receiving 5 citations.

Distribution of dystrophin gene deletions in a Chinese population

Abstract: ObjectiveTo describe the deletion patterns and distribution characteristics of the dystrophin gene in a Chinese population of patients with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD).MethodsPatients with DMD/BMD were recruited. Deletions in 19 exons of the dystrophin gene were evaluated using accurate multiplex polymerase chain reaction (PCR).ResultMultiplex PCR identified deletions in 238/401 (59.4%) patients with DMD/BMD. Of these, 196 (82.4%) were in the distal hotspot, 32 (13.4%) were in the proximal hotspot, five (2.1%) were in both regions and five (2.1%) were in neither hotspot. Deletions were classified into 54 patterns. Exon 49 was the most frequently deleted. The reading frame rule was upheld for 91.9% of cases.ConclusionAccurate multiplex PCR for 19 exons is an effective diagnostic tool.

Gene editing restores dystrophin expression in a canine model of Duchenne muscular dystrophy

Abstract: Mutations in the gene encoding dystrophin, a protein that maintains muscle integrity and function, cause Duchenne muscular dystrophy (DMD) The deltaE50-MD dog model of DMD harbors a mutation corresponding to a mutational “hotspot” in the human DMD gene We used adeno-associated viruses to deliver CRISPR gene editing components to four dogs and examined dystrophin protein expression 6 weeks after intramuscular delivery (n = 2) or 8 weeks after systemic delivery (n = 2) After systemic delivery in skeletal muscle, dystrophin was restored to levels ranging from 3 to 90% of normal, depending on muscle type In cardiac muscle, dystrophin levels in the dog receiving the highest dose reached 92% of normal The treated dogs also showed improved muscle histology These large-animal data support the concept that, with further development, gene editing approaches may prove clinically useful for the treatment of DMD

Single-cut genome editing restores dystrophin expression in a new mouse model of muscular dystrophy

Abstract: Duchenne muscular dystrophy (DMD) is a severe, progressive muscle disease caused by mutations in the dystrophin gene. The majority of DMD mutations are deletions that prematurely terminate the dystrophin protein. Deletions of exon 50 of the dystrophin gene are among the most common single exon deletions causing DMD. Such mutations can be corrected by skipping exon 51, thereby restoring the dystrophin reading frame. Using clustered regularly interspaced short palindromic repeats/CRISPR-associated 9 (CRISPR/Cas9), we generated a DMD mouse model by deleting exon 50. These ΔEx50 mice displayed severe muscle dysfunction, which was corrected by systemic delivery of adeno-associated virus encoding CRISPR/Cas9 genome editing components. We optimized the method for dystrophin reading frame correction using a single guide RNA that created reframing mutations and allowed skipping of exon 51. In conjunction with muscle-specific expression of Cas9, this approach restored up to 90% of dystrophin protein expression throughout skeletal muscles and the heart of ΔEx50 mice. This method of permanently bypassing DMD mutations using a single cut in genomic DNA represents a step toward clinical correction of DMD mutations and potentially those of other neuromuscular disorders.

In vivo non-invasive monitoring of dystrophin correction in a new Duchenne muscular dystrophy reporter mouse.

Abstract: Duchenne muscular dystrophy (DMD) is a fatal genetic disorder caused by mutations in the dystrophin gene. To enable the non-invasive analysis of DMD gene correction strategies in vivo, we introduced a luciferase reporter in-frame with the C-terminus of the dystrophin gene in mice. Expression of this reporter mimics endogenous dystrophin expression and DMD mutations that disrupt the dystrophin open reading frame extinguish luciferase expression. We evaluated the correction of the dystrophin reading frame coupled to luciferase in mice lacking exon 50, a common mutational hotspot, after delivery of CRISPR/Cas9 gene editing machinery with adeno-associated virus. Bioluminescence monitoring revealed efficient and rapid restoration of dystrophin protein expression in affected skeletal muscles and the heart. Our results provide a sensitive non-invasive means of monitoring dystrophin correction in mouse models of DMD and offer a platform for testing different strategies for amelioration of DMD pathogenesis. Dystrophin-deficient mice are used to test corrective strategies for Duchenne muscular dystrophy, but evaluation of dystrophin expression requires collection of tissue samples from specific muscles and time points. Here, the authors generate mice in which dystrophin expression is coupled to luciferase, and show that bioluminescence allows non-invasive monitoring of dystrophin expression following genome editing.

The First Comprehensive Cohort of the Duchenne Muscular Dystrophy in Iranian Population: Mutation Spectrum of 314 Patients and Identifying Two Novel Nonsense Mutations.

Abstract: Mutations in the dystrophin gene could cause Duchenne muscular dystrophy (DMD), which is the most common muscular disorder in pediatrics. Considering the growing evidence on appropriateness of gene therapies for DMD, precise genetic diagnosis seems essential. Hence, we conducted a study to determine mutational patterns in Iranian children with DMD. To detect all probable large mutations in the dystrophin gene, 314 DMD patients were evaluated using the multiplex ligation-dependent probe amplification (MLPA). Subjects who were MLPA-negative underwent the next generation sequencing (NGS) to identify potential point mutations. MLPA detected deletions (79.93%) and duplications (5.41%) along the dystrophin gene of 268 patients. Distribution of large mutations was heterogeneous and followed hotspot pattern throughout the gene. From 46 patients who were MLPA-negative, 43 exhibited point mutations including nonsense in 7.64%, frameshifts in 4.77%, splicing in 0.96%, and missense variations in 0.32% of participants. Most of the point mutations were located between exons 19 and 40. In three patients (1%), no mutation was found using either MLPA or NGS. Two subjects had novel nonsense mutations (L1675X and E1199X) in their dystrophin gene, which were considered as the possible reason for elimination of major domains of the gene. The results of this study provided invaluable information regarding the distribution of various large and small mutations in Iranian individuals with DMD. Besides, the novel nonsense mutations L1675X and E1199X were identified within the highly conserved residues, leading to elimination of significant domains of the dystrophin gene.