CRISPR technology has shown strong results treating a baby with a life-threatening liver cell mutation, with scientists saying it is the first documented use of personalised gene-editing treatment.

US scientists say they have treated a boy named KJ Muldoon who had severe carbamoyl-phosphate synthetase 1 (CPS1) deficiency, diagnosed 48 hours after birth.

The condition, which was caused by two truncating CPS1 genes, leads to hyperammonaemia because of an inability to create the CPS1 enzyme, which is involved in the production of urea.

It has an estimated 50% mortality rate in early infancy, said the team led by the University of Pennsylvania and Children’s Hospital of Philadelphia.