Epidermolysis Bullosa (EB) is a genetic skin disease characterized by the formation of blisters and bullae on the skin and mucous membranes following minor trauma or friction. Common clinical symptoms include the appearance of blisters, blood blisters, and erosion on the skin. Depending on the site of onset, hereditary EB can be divided into three types: Simplex Epidermolysis Bullosa (EBS), Junctional Epidermolysis Bullosa (JEB), and Dystrophic Epidermolysis Bullosa (DEB). Mutations in the COL7A1 gene are the cause of Dystrophic Epidermolysis Bullosa (DEB), and the different clinical phenotypes presented by DEB are related to the mutation site and form of the COL7A1 gene. The COL7A1 gene encodes type VII collagen protein, which forms anchoring fibrils that bind the dermal tissue to the epidermal tissue. Functional deficiency of anchoring fibrils caused by COL7A1 mutations makes the patient's skin extremely fragile, easily causing blisters or tears due to minor friction or trauma. To date, at least 324 pathogenic mutations related to DEB have been found in the COL7A1 gene, including nonsense, missense, deletion, insertion, splicing, and regulatory mutations ^[1]. Research shows that Col7a1 gene homozygous knockout mice exhibit high mortality after birth, with hemorrhagic blisters appearing on the palms of the forepaws and hind paws within 24-48 hours, followed by severe RDEB symptoms ^[2]. This is one of the commonly used preclinical models for DEB research.

Col7a1 knockout (KO) mice, constructed by using gene editing technology to knock out the homologous gene Col7a1 of human COL7A1 in mice, serve as a research model for Dystrophic Epidermolysis Bullosa (DEB). Homozygous Col7a1 KO mice lack the expression of the Col7a1 gene and COL7A1 protein, and exhibit symptoms of skin redness and blistering on the palms of the fore and hind paws on the first day after birth, and die within three days after birth. Histological examination results show that the skin of Col7a1 KO mice exhibits significant subcutaneous edema, and there is a separation between the epidermis and dermis, which is roughly the same as the pathogenesis and pathological characteristics of human Dystrophic Epidermolysis Bullosa (DEB) in the clinic. Therefore, Col7a1 KO mice can be used for the mechanistic study of Dystrophic Epidermolysis Bullosa (DEB), as well as the development, screening, and evaluation of therapeutic drugs.