New Delhi: For the first time, genetically modified human embryos have been developed in the US and Kashmir-born doctor Sanjeev Kaul has played a lead role in this breakthrough.
Scientists have now demonstrated an effective way of using a gene-editing tool to correct a disease-causing gene mutation in human embryos and stop it from passing to future generations.
A team of scientists has altered human embryos using a new technique called CRISPR CAS9 that edits genes and in this case it helped remove a fatal mutation that leads to heart attacks.
Only selected healthy embryos were allowed to grow further that too only for a few days. The embryos were not implanted in humans.
The big step forward is that a higher percentage embryos were found to have been repaired in this American experiment than earlier attempts.
CRISPR holds promise for correcting mutations in the human genome to prevent genetic disease. Using an enzyme called Cas9, it is possible to snip a specific target sequence on a mutant gene.
The new study found that human embryos effectively repair these breaks in the mutant gene using the normal copy of this gene from a second parent as a template.
The resulting embryos contain now repaired, mutation-free copies of this gene.
The technique already has been used in animals for generating mutant models; however, the new study is the first to demonstrate that technique can be used in human embryos to convert mutant genes back to normal.
The study also demonstrated a way for overcoming a crucial problem in genome editing in embryos known as mosaicism.
Mosaicism refers to an outcome when not all cells in a multicellular embryo get repaired and some cells still carry a mutation.
“Every generation on would carry this repair because we have removed the disease-causing gene variant from that family’s lineage,” said senior author Shoukhrat Mitalipov, PhD, who directs the Center for Embryonic Cell and Gene Therapy at Oregon Health and Science University (OHSU), in Portland, Oregon, USA.
“By using this technique, it is possible to reduce the burden of this heritable disease on the family and eventually the human population.”
The study provides new insight into a technique that could apply to thousands of inherited genetic disorders affecting millions of people worldwide.
The gene-editing technique described in this study, done in concert with in vitro fertilisation, could provide a new avenue for people with known heritable disease-causing genetic mutations to eliminate the risk of passing the disease to their children.
“If proven safe, this technique could potentially decrease the number of cycles needed for people trying to have children free of genetic disease,” said co-author Paula Amato, associate professor of obstetrics and gynaecology in the OHSU School of Medicine.
Designer babies could be in the offing.
“The ethical considerations of moving this technology to clinical trials are complex and deserve significant public engagement before we can answer the broader question of whether it’s in humanity’s interest to alter human genes for future generations.”
Existing ethical guidelines did not permit the team to implant the genetically modified human embryos into women.