Duchenne muscular dystrophy (DMD) is a severe, progressive, and debilitating X-linked disorder characterized by muscle wasting. This condition precipitates difficulties with movement, eventually necessitating assisted ventilation, and often leads to premature death. The primary cause of DMD is mutations in the dystrophin muscular dystrophy (DMD) gene, which encodes the dystrophin protein. These mutations effectively eliminate the production of dystrophin protein in muscle tissues, instigating muscle atrophy and a myriad of complications ^[1]. The absence of dystrophin protein culminates in the disintegration of the dystrophin-associated protein complex (DAPC) within the muscle membrane. This disintegration disrupts the interaction between actin and the extracellular matrix, rendering muscles devoid of dystrophin more susceptible to damage. This susceptibility results in the progressive loss of muscle tissue and function, as well as the development of cardiomyopathy ^[2]. DMD-Q995* mice carry a c.2983C>T (p.Q995) mutation in the Dmd gene, which results in the production of a premature termination codon (PTC). In eukaryotes, the nonsense-mediated mRNA decay (NMD) pathway degrades mRNAs containing PTCs to reduce errors in gene expression. These abnormal mRNAs may encode harmful gain-of-function or dominant-negative proteins that can damage normal human physiological mechanisms. In DMD-Q995* mice, the mutation and the NMD pathway together result in the degradation of most Dmd transcripts. The remaining transcripts can only encode truncated dystrophin proteins that lack normal function, leading to the loss of dystrophin function ^[3-5]. This model, due to the lack of normal dystrophin expression, exhibits a series of muscle disease phenotypes similar to the clinical presentation of Duchenne muscular dystrophy (DMD), and can be used for research on DMD. Homozygous female mice and heterozygous males of this strain are viable and fertile.

Duchenne muscular dystrophy (DMD) is a severe, progressive, and debilitating X-linked disorder characterized by muscle wasting. This condition precipitates difficulties with movement, eventually necessitating assisted ventilation, and often leads to premature death. The primary cause of DMD is mutations in the dystrophin muscular dystrophy (DMD) gene, which encodes the dystrophin protein. These mutations effectively eliminate the production of dystrophin protein in muscle tissues, instigating muscle atrophy and a myriad of complications ^[1]. The absence of dystrophin protein culminates in the disintegration of the dystrophin-associated protein complex (DAPC) within the muscle membrane. This disintegration disrupts the interaction between actin and the extracellular matrix, rendering muscles devoid of dystrophin more susceptible to damage. This susceptibility results in the progressive loss of muscle tissue and function, as well as the development of cardiomyopathy ^[2]. Dmd-Q995X(DBA/2.B6) mice carry a c.2983C>T (p.Q995*) mutation in the Dmd gene, which introduces a premature termination codon (PTC) triggering nonsense-mediated mRNA decay (NMD) in eukaryotes. NMD degrades PTC-containing aberrant mRNAs to minimize gene expression errors, as these mRNAs may translate into harmful gain-of-function or dominant-negative proteins disrupting physiological mechanisms. The mutation combined with the murine NMD mechanism leads to the degradation of most Dmd transcripts in Dmd-Q995X(DBA/2.B6) mice, with remaining transcripts encoding nonfunctional truncated dystrophin, resulting in loss of dystrophin function ^[3-5]. Additionally, the inherent muscle regeneration dysfunction in the DBA/2 strain exacerbates myopathic phenotypes, including significant muscle atrophy, fibrosis, and pronounced muscle weakness, more accurately mimicking human DMD progression and severity ^[6]. This makes Dmd-Q995X(DBA/2.B6) mice, with their lack of functional dystrophin, ideal for modeling Duchenne muscular dystrophy (DMD) and evaluating therapeutic strategies.

Acad8 is located on chromosome 9 of mice. SgRNA and ssDNA will be designed using Nuclease Technology; Acad8 conditional knockout mice will be obtained by high-throughput electroporation of fertilized eggs. After sexual maturity, sperm will be collected for cryopreservation.

Dmd is located on chromosome X of mice. Nuclease Technology was used to design sgRNA; Dmd knockout mice were obtained by applying high-throughput electroporation of fertilized eggs. After sexual maturity, sperm were collected for cryopreservation.

Dmd is located on chromosome X of mice. SgRNA and ssDNA will be designed using Nuclease Technology; Dmd conditional knockout mice will be obtained by high-throughput electroporation of fertilized eggs. After sexual maturity, sperm will be collected for cryopreservation.

Abraxas1 is located on chromosome 5 of mice. Nuclease Technology will be used to design sgRNA; Abraxas1 knockout mice will be obtained by applying high-throughput electroporation of fertilized eggs. After sexual maturity, sperm were collected for cryopreservation.