Hepatorenal tyrosinaemia (HT1) is an autosomal recessive disorder of tyrosine degradation resulting in hepatic and renal dysfunction, neurological sequelae may occur in some patients. The use of nitisinone (NTBC) has revolutionised treatment and outcome of this disorder. NTBC has to be combined with a low protein diet. While NTBC modulates the disease course in HT1 patients, several issues are open. Optimal dosage, doses per day, therapeutic range of NTBC concentration, mode of …