The ALPL gene encodes for the tissue-nonspecific alkaline phosphatase (TNSALP) enzyme, a membrane-bound glycoprotein. This enzyme is expressed in a variety of cellular tissues, most notably in the liver, bone, and kidney, as well as in other areas like teeth and mesenchymal stem cells ^[1]. Its primary function is to act as a hydrolase, removing phosphate groups from molecules. This is a critical function for skeletal and dental mineralization, where it hydrolyzes inorganic pyrophosphate (a mineralization inhibitor) into phosphate, which then combines with calcium to form bone ^[2]. Mutations in the ALPL gene lead to hypophosphatasia (HPP), a rare inherited metabolic disease characterized by defective bone and tooth mineralization, rickets, osteomalacia, and in severe cases, seizures and respiratory complications. The severity of HPP varies, ranging from mild forms with dental issues to life-threatening perinatal forms ^[3]. Variations in the ALPL gene may also be associated with other diseases, such as osteoporosis. Research has found a high frequency of homozygous common ALPL gene variants in adult patients with atypical femoral fractures or with biochemical/clinical signs of hypophosphatasia (HPP). This suggests that variations in the ALPL gene may be linked to an increased risk of these fractures ^[4]. Furthermore, the expression and function of the ALPL gene may be relevant to cancer immunotherapy. Studies have shown that an alkaline phosphatase isoform, known as ALPL-1, is highly expressed in osteosarcoma (OS) ^[5]. The Alpl-KO mouse is a knockout (KO) model in which the exon 3~4 of the Alpl gene (homologous to the human ALPL gene) has been deleted via gene-editing technology. Preliminary validation data indicate that homozygous Alpl-KO mice have a short lifespan, dying within four weeks when given a specialized diet. If they are not provided with this dietary support, no surviving homozygous individuals are obtained. This model can be used to study the pathogenic mechanisms of diseases such as hypophosphatasia (HPP), osteoporosis, and osteosarcoma (OS), and to provide a basis for developing related therapeutic strategies.

The AGXT gene, mapping to chromosome 2q37.3, encodes alanine-glyoxylate aminotransferase (AGT), a pyridoxal 5'-phosphate-dependent homotetrameric enzyme predominantly expressed in hepatic peroxisomes ^[1]. AGT is central to glyoxylate metabolism, catalyzing its transamination to glycine and preventing its oxidation to oxalate ^[1]. Primary Hyperoxaluria Type 1 (PH1), a rare autosomal recessive disorder affecting approximately 1-3 per million individuals, arises from over 175 identified pathogenic mutations in AGXT. These mutations typically result in deficient or mislocalized AGT, leading to marked overproduction of oxalate ^[2]. The ensuing hyperoxaluria causes deposition of calcium oxalate in the kidneys, manifesting as nephrolithiasis and nephrocalcinosis, which can progress to end-stage renal disease ^[3]. In severe cases, systemic oxalosis can occur ^[4]. Agxt-deficient mice serve as critical preclinical models, faithfully mirroring the biochemical and pathological features of PH1 and enabling the evaluation of diverse therapeutic modalities, including enzyme replacement, substrate reduction, and gene therapy. The Agxt-KO mouse is a gene knockout model created using gene-editing techniques to knock out the coding sequence of the Agxt gene (the homolog of the human AGXT gene) in mice. This model is used to research the pathogenic mechanisms of primary hyperoxaluria and develop related therapeutic strategies.

Progressive Familial Intrahepatic Cholestasis Type 3 (PFIC3) is a rare, life-threatening autosomal recessive hereditary liver disease caused by mutations in the ABCB4 gene (also known as MDR3 in humans and MDR2 in rodents) ^[1-3]. The disease is characterized by early persistent cholestasis, leading to the accumulation of bile acids in the liver and subsequent hepatocellular damage. Clinical manifestations of PFIC3 include jaundice (yellowing of the skin and eyes), pruritus, fatigue, and growth failure. If untreated, it can progress to cirrhosis and liver failure in early childhood ^[4]. The ABCB4 gene encodes Multidrug Resistance Protein 3 (MDR3), a member of the ATP-binding cassette (ABC) transporter family, which is a liver-specific phosphatidylcholine (PC) transporter ^[5]. MDR3 is primarily expressed on the canalicular membrane of hepatocytes (the membrane that forms bile canaliculi). It is involved in the transport of phosphatidylcholine from the hepatocyte membrane to vesicles, which are then secreted into bile, forming PC-cholesterol vesicles and a small number of mixed bile salt micelles ^[6]. Mutations in ABCB4 lead to the loss or dysfunction of MDR3, reducing PC levels in bile, destabilizing micelles, and increasing bile salt concentrations, thereby causing cholestasis and hepatocellular injury ^[7]. Studies have shown that knocking out the Abcb4 gene in mice leads to a phenotype similar to human PFIC3, although the severity and progression of the disease vary across different mouse strains. In the commonly used C57BL/6 background, Abcb4-KO mice exhibit a relatively mild pathological phenotype due to lower bile salt toxicity, and a diet enriched in hydrophobic bile salts is typically required to induce a more human-like PFIC3 phenotype ^[8-10]. In contrast, Abcb4-KO mice in the FVB background naturally exhibit most of the biomarkers and pathological features of human PFIC3, including hepatomegaly, liver fibrosis, and early disease onset with more severe progression ^[10-11]. Cyagen has generated the Abcb4-KO(FVB) mouse model by knocking out the Abcb4 gene in FVB mice. This model lacks the Abcb4 gene and protein expression and exhibits liver enlargement, elevated liver function markers, and increased total bilirubin. Histopathological examination shows hepatocyte necrosis, inflammatory cell infiltration, connective tissue proliferation, bile duct proliferation, and liver fibrosis.

The ATP7B gene encodes a copper-transporting ATPase β-peptide that is a member of the P-type cation-transporting ATPase family, which uses the energy stored in adenosine triphosphate (ATP) molecules to transport metals into and out of cells. The ATP7B protein consists of multiple transmembrane structural domains, an ATPase consensus sequence, a hinge structural domain, and a phosphorylation site, as well as at least two putative copper-binding sites ^[1]. This protein is found mainly in the liver and to a lesser extent in the kidney and brain, and functions as a copper-transporting ATPase that plays a role in transporting copper from the liver to other parts of the body. Copper is an important component of certain enzymes that maintain normal cellular function, and the ATP7B protein is important for the removal of excess copper from the body. Mutations in this gene are associated with Wilson disease (WD), which is characterized by the accumulation of copper to toxic levels that damage tissues and organs such as the liver and brain as the removal of excess copper from the body is compromised with the absence of the functional ATP7B protein ^[2-4]. This strain is an Atp7b deletion mouse model, which uses gene editing technology to knock out Atp7b, the homolog of the human ATP7B gene in mice that lack the expression of ATP7B protein and can be used in the study of disorders related to copper metabolisms such as Wilson's disease, acute liver failure, and steatohepatitis. The heterozygous Atp7b KO mice are viable and fertile, and homozygous mice have a reduced life expectancy.

Stargardt disease (STGD), a hereditary macular dystrophy, is characterized by the presence of yellowish flecks within the retinal pigment epithelium (RPE), ultimately culminating in macular atrophy. Typically manifesting in childhood and adolescence, STGD leads to progressive central vision loss and mild dyschromatopsia. Fundoscopic examination may reveal pale yellow lesions exhibiting a characteristic gold foil-like sheen, accompanied by yellow-white spots surrounding the posterior pole. In advanced stages, atrophy of the RPE, photoreceptors, and choriocapillaris is observed. This bilateral and typically synchronous condition affects both eyes with comparable incidence across sexes, estimated between 1/8,000 and 1/13,000. STGD is predominantly an autosomal recessive disorder, with mutations in the ABCA4 gene accounting for approximately 95% of cases. ABCA4 encodes a retina-specific ABC transporter protein crucial for the clearance of retinal derivatives and toxic metabolites generated during rhodopsin photobleaching. Consequently, ABCA4 mutations result in the accumulation of these cytotoxic substances, triggering apoptosis of both RPE and photoreceptor cells and ultimately driving retinal degeneration. Notably, ABCA4 mutations have been implicated in a spectrum of retinal diseases, including STGD, cone-rod dystrophy (CRD), age-related macular degeneration (AMD), and retinitis pigmentosa (RP), with the specific clinical phenotype correlating with the nature and severity of the ABCA4 mutation. This strain is an Abca4 gene knockout (KO) mouse model. Gene-editing technology was used to delete the protein-coding sequence of the Abca4 gene (the homolog of the human ABCA4 gene) in mice. Previous studies have demonstrated that Abca4 KO mice exhibit delayed dark adaptation following photobleaching and a slow progression of photoreceptor degeneration^[1]. Homozygous Abca4-KO mice are viable and fertile.

The Mmut gene encodes the mitochondrial enzyme methylmalonyl-CoA mutase (MCM), a protein critical for the metabolism of specific amino acids and fatty acids, cholesterol catabolism, and energy production. This gene is widely expressed, with particularly high levels in the liver and kidney. Mutations in Mmut cause methylmalonic acidemia (MMA), a severe autosomal recessive genetic disorder characterized by the accumulation of methylmalonic acid in blood and urine, which triggers life-threatening metabolic crises, developmental delay, and progressive renal failure. The refractoriness of this condition to conventional dietary and pharmacological management has led some patients to undergo elective liver transplantation (LT) or combined liver-kidney transplantation (LKT) to maintain metabolic stability. While LT or LKT reduces the risk of metabolic decompensation, post-transplant patients still exhibit biochemical abnormalities such as elevated methylmalonic acid levels in blood and cerebrospinal fluid. Patients receiving liver transplantation alone remain at risk of renal insufficiency, basal ganglia damage, and optic neuropathy. Additionally, long-term immunosuppressive therapy post-transplant may induce toxic reactions and increase the risk of malignancy ^[1-2]. Current therapeutic strategies for MMA focus on developing drugs that enhance MCM activity or bypass metabolic blocks, including chaperone therapy to improve protein folding and stability, enzyme replacement therapy, and gene therapy strategies to deliver functional Mmut gene copies ^[3-4]. B6-Mmut*M698K/Mmut KO mice are a MMA disease model generated by crossing Mmut-knockout mice (with exon 3 deleted) with Mmut-mutant mice (carrying the p.M698K mutation in exon 12). Homozygous deletion of the gene results in embryonic lethality, and homozygous mutant mice die within 1 day of birth. The p.M698K (ATG to AAG) mutation carried by B6-Mmut*M698K/Mmut KO mice is equivalent to the p.M700K (ATG to AAG) mutation in the human MMUT gene. This model can be used to study the pathogenic mechanisms and therapeutic approaches for MMA.

The F8 gene encodes coagulation factor VIII (FVIII), a large plasma glycoprotein crucial for the intrinsic pathway of blood coagulation. This gene generates two alternatively spliced transcripts, with the larger isoform, variant a, forming a non-covalent complex with von Willebrand factor (vWF) that circulates in plasma. Under normal physiological conditions, when a blood vessel is injured, platelets and clotting factors aggregate at the site of injury to form a blood clot and prevent further bleeding. In this process, FVIII functions as a cofactor, working synergistically with activated factor IX (FIXa) to activate factor X (FX), subsequently generating fibrin and stabilizing the blood clot. Deficiency of the F8 gene leads to hemophilia A (HA), an X-linked recessive bleeding disorder that primarily affects males. Patients often present with spontaneous or post-traumatic bleeding that may be difficult to control, with severe cases risking disability or life-threatening complications due to internal bleeding and joint hemorrhage. Clinically, exogenous FVIII supplementation is effective in managing hemophilia A symptoms. In recent years, advances in gene therapy and gene editing have offered new hope for HA treatment, aiming for a long-term or permanent cure by repairing or replacing the defective F8 gene. The B6-F8 KO mouse is a hemophilia A (HA) research model developed through gene-editing techniques, where the murine F8 gene, homologous to the human F8 gene, is knocked out. Studies have shown that homozygous F8 knockout mice are viable and develop normally ^[1]. Since the murine F8 gene is located on the X chromosome, hemizygous male and homozygous female B6-F8 KO mice exhibit a consistent phenotype with significantly lower FVIII activity compared to wild-type mice, prolonged clotting time, and a classic hemophilia A phenotype ^[1].

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-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.

Cystic Fibrosis (CF) is an autosomal recessive disorder causing severe damage to the lungs, digestive system, and other organs. It thickens mucus, sweat, and digestive fluids, blocking ducts and channels. The disease manifests as a persistent cough, hyperinflation of lung lobes, chronic nasal congestion, headaches, sleep disorders, digestive and reproductive system disorders, and nutritional and growth development disorders. CF is caused by mutations in the CF-transmembrane conductance regulator (CFTR) gene, which encodes a cAMP-dependent chloride ion channel protein. Abnormal CFTR function can cause transmembrane transport disorders of chloride ions and bicarbonate, leading to mucus obstruction in exocrine glands, and affecting respiration, digestion, endocrine, and reproduction ^[1-2]. Cftr-KO mice are a gene-knockout (KO) model. Using gene-editing technology, exons 5-6 of the Cftr gene in mice have been knocked out. This model can be used for research on the pathogenic mechanism of cystic fibrosis and the development of related treatment methods. Homozygous Cftr-KO mice start to die at 2 weeks of age, and prophylactic PEG treatment can improve their survival rate ^[3]. This strain requires feeding with intestinal cleansers to maintain survival after 3 weeks of age.