Some of these diseases in humans, such as alpha 1-antitrypsin deficiency, type I tyrosinemia, Progressive Familial Intrahepatic Cholestasis type III or Wilsons’ disease, Crigler-Najjar syndrome type I, ornithine transcarbamylase (OTC) deficiency, type IIa familial hypercholesterolemia and several coagulation defects have a genetic basis, and could be potentially treated by the expression of heterologous genes delivered by viral vectors with a target specificity restricted to the cellular elements of this organ. This evidence concerns the gene OTC and Crigler-Najjar syndrome type 1.