Dmd-Q995X(DBA/2.B6) Mouse

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.