Crispr first as disease-causing mutation edited in human embryos

The Crispr–Cas9 genome editing tool has been used to correct a disease-causing mutation in human embryos for the first time.

Hypertrophic cardiomyopathy is a serious heart condition caused by a single genetic mutation that affects about 0.2% of people. Although it can be treated with medication the underlying genetic cause currently cannot be cured and those who carry the faulty gene have a 50% chance of passing it to their children.

Researchers in Korea and the US used Crispr to precisely target the mutation in embryos with one faulty and one healthy copy of the MYBPC3 gene. When the faulty sequence of DNA was cut using the Cas9 enzyme, the cells repaired the damage using the healthy copy of the gene as a template, which resulted in a ‘wild type’ embryo with two healthy copies of the gene. The technique worked in about two-thirds of the embryos treated.

In theory, interventions like this could be used to correct disease-causing mutations in IVF embryos before they are implanted, preventing genetically inherited diseases being passed down the generations. But such clinical applications are still a long way off, and the researchers say this approach still needs to be tested for accuracy and safety.