Scientists in Oregon successfully fixed a disease-carrying gene in human embryos. It was the first time this has been done. This small effort could be a big step in preventing inherited, or gene-related diseases. A research team at Oregon Health & Science University edited out a gene that causes a heart problem and kills young people. Their work was published in the journal Nature. Dr. Paula Amato is one of the scientists who worked on the study. She explained how it happened. The team used sperm from a man who carries the heart-damaging gene. They injected his sperm into eggs, and at the same time injected a gene-editing tool called CRISPR-Cas-9. The CRISPR acts like scissors - cutting out the defective DNA.