The invention relates to a nucleic acid construct carrying ATP7B protein, an expression vector and a viral particle comprising the nucleic acid construct, and their use for treatment of Wilson' s disease and other conditions caused by a deficiency or dysfunction of ATP7B protein. An AAV vector devised according to the invention significantly reduced urine Cu excretion, and liver Cu content in Wilson' s disease mice treated with the vector, while ceruloplasmin activity was significantly restored. On the other hand, the administration of the vector resulted in the normalization of serum transaminases levels and of liver histology, together with a marked reduction of the inflammatory infiltrate.