Anchor: A joint South Korea-U.S. research team has successfully edited the DNA in human embryos to correct a genetic defect causing incurable diseases. The technique, if put into practice after clinical tests, is expected to help prevent many genetic diseases by correcting the disease-causing mutation. But as our Bae Joo-yon reports, the breakthrough is not without ethical concerns.
 
Report: Dir. Kim Jin-soo of the Center for Genome Engineering at the Institute for Basic Science announced Thursday that his collaboration with U.S. researchers successfully corrected a disease-causing mutation in human embryos.

[Sound bite: Kim Jin-soo - Director, Center for Genome Engineering, Institute for Basic Science (Korean)]
“We corrected a targeted DNA piece without generating mosaics, creating an embryo with completely corrected cells. This signifies a huge technical progress.”

They fixed the mutated gene in human embryos which causes the heart disorder hypertrophic cardiomyopathy.

Kim and Dr. Shoukhrat Mitalipov of the Oregon Health and Science University used CRISPR-Cas9 molecular scissors, or enzymes that can cut DNA molecules for genome editing.
 
In a separate news conference, Mitalipov explained that repair occurs right after fertilization, so by the time an embryo develops into a few cells, its old DNA was repaired.
 
[Sound bite: Shoukhrat Mitalipov- Director, Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University (English)]
 "So it's actually molecular scissors that would allow you to direct the scissors into a very specific site and specific gene, in this case we would direct into the mutant gene and induce a cut in the DNA. So the DNA is a kind of long string and this molecular scissors would cut where the mutation is. The embryos usually will respond by repairing this cut."
 
The technique could make it possible for people with genetic diseases to have healthy babies by editing disease-causing mutations in embryos in the process of artificial insemination.
 
The researchers said they expect the new technique will likely have a significant impact on hundreds of patients suffering from rare diseases, including hemophilia, sickle-cell disease and Huntington’s disease.
 
However, the study is expected to spark ethical controversy given that it could also be used to produce customized babies.

In the latest research, the South Korean team provided the molecular scissors while the American team carried out the correction process on the human embryos.

The results of the latest study were published in the Wednesday edition of the international science journal, "Nature".
Bae Joo-yon, KBS World Radio News.