To establish a Wilson’s disease (WD) mouse model carrying the homozygous Asian-prevalent Atp7b R778L mutation and characterize its phenotype.

WD is an autosomal recessive disorder caused by mutations in the ATP7B gene, which encodes a copper-transporting P-type ATPase crucial for regulating copper homeostasis. The R778L variant is the most common among Asian WD patients, contributing to 20% of cases. Current treatments rely on lifelong chelation and dietary restriction, highlighting the need for a mouse model with this Asian-specific mutation to recapitulate human disease for future alternative cure therapy.

Using CRISPR/Cas9 technique, we established a mutant knock-in mouse model carrying the homozygous Atp7b R780L mutation, equivalent to the human R778L mutation. Non-transgenic wild-type (Atp7b ^WT/WT) and heterozygous (Atp7b ^R780L/WT) littermates served as controls. Mice were divided into two groups: receiving either standard water or water supplemented with 750 ppm copper from 9 to 18 weeks of age.

Serum ceruloplasmin level, liver enzymes, copper concentrations, hepatic pathology, and motor performance were assessed. Liver and brain copper were quantified using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS).

Atp7b ^R780L/R780L mutant mice showed age-dependent locomotor decline compared to wild-type mice (p=0.04), markedly reduced serum ceruloplasmin activity (1027±429.7 vs. 3009±552.3 mU/mL, p<0.001), elevated liver enzymes, (77.35±38.33 vs. 54.11±14.42 U/L, p=0.002), dramatically increased liver copper concentration (145.2±46.68 vs. 8.461±4.292 μg/g, p<0.001), higher brain copper concentration (7.228±1.588 vs. 5.757±0.728 μg/g, p<0.001), and significantly lower serum total copper (45.77±18.63 vs. 115.0±29.74 μΜ, p<0.001).

Histologically, Atp7b ^R780L/R780L mice showed increased hepatic inflammation (Brunt’s grade 0.773±0.344 vs. 0.375±0.246, p<0.01), and increased abnormal bile duct proliferations, as indicated by a higher abnormal CK19-positive area ratio (1.844±1.004 vs. 0.875±0.613,  p<0.01).

Homozygous Atp7b ^R780L/R780L mice recapitulate key features of human WD phenotype. This model provides a robust platform for exploring future gene or nucleic acid therapies to advance personalized medicine for WD.