Scientists have for the first time corrected a genetic defect in newly created human embryos, demonstrating that contentious “gene editing” technology could prevent the transmission of some inherited diseases to future generations.

Teams at Oregon Health & Science University (OHSU) and Salk Institute in the US, working with colleagues in South Korea and China, used a gene editing tool called Crispr to repair a DNA mutation that causes hypertrophic cardiomyopathy. The inherited heart condition affects one person in 500 and is the most common cause of sudden death in apparently healthy young athletes. Gene editing involves altering DNA to change the nature of a living cell.

The researchers created the embryos with eggs from IVF donors, which were injected with sperm from a man suffering from the heart condition and at the same time with a Crispr enzyme designed to fix the genetic defect.