Chinese researchers have used a gene-editing technique to repair a defect in a human embryo, moving biomedicine one step closer to a cure for inheritable diseases caused by genetic mutations, scientists said.

The research, published last month in the scientific journal Molecular Therapy, involved “base editing” a gene with a mutation for Marfan syndrome, a genetic disorder that affects the body’s connective tissue.

The syndrome afflicts about 1 in 5,000 people and is caused by the FBN1 mutation.

A group of scientists at ShanghaiTech University and Third Affiliated Hospital of Guangzhou Medical University used the base-editing technique to replace part of the DNA instead of the whole gene in human cells and embryos with the mutation.

The method succeeded in 16 out of 18 human embryos, the study said, showing none of the negative side-effects that appeared in previous studies.

“This study may provide a potential gene therapy for Marfan syndrome patients with this kind of pathogenic mutation,” said Huang Xingxu, one of the lead authors of the study and a genetics professor at ShanghaiTech University.

“The treatment will benefit the children of patients with genetic diseases.”

While base editing has been used to correct mutations in human cells and cloned human embryos, it is the first time it has been applied to correct a genetic mutation in viable human embryos.

These gene-edited embryos could be implanted into a uterus, as opposed to non-viable ones used in prior studies.

“These results have instilled some hope that a genetic disease with no current treatment is potentially correctable with a cutting-edge genome-editing tool,” the study said.

Sarah Robertson, a reproductive immunology professor and director of the Robinson Research Institute at the University of Adelaide in Australia, said the study could be the start of using gene editing to treat inheritable diseases.

“The correction of Marfan syndrome using base editing is one step closer to a CRISPR therapy in humans,” said Robertson, who was not involved in the study.

CRISPR is a gene-editing technique used to edit DNA at precise locations. Huang’s team used CRISPR/Cas9, one of the newest genome editing tools in the CRISPR family and one of the most promising for treating diseases such as HIV or cancer.

The researchers behind the Chinese study said there was more work to do before the technology could be used to correct mutations in an embryo that would be allowed to develop into a fetus.

“Overall, this is a pilot study that provided proof of concept of embryo gene therapy. But there is still a long way to go to use it in clinics,” Huang said.

The team is also working on developing base-editing strategies for other mutations.

There are more than 7,000 mutations that cause diseases, and the number rises with the development of molecular diagnosis.

Reference: China Science