Five cloned monkeys have been born with genes that were edited to cause mental illness, a team of Chinese researchers announced,.
Although such experiments could help develop new drugs in future, the experiment is likely to raise fresh ethical concerns about the mass cloning of animals with medical conditions induced by humans. The announcement also follows the recent confirmation that world’s first gene-edited human babies have been born in China, following an unauthorised experiment that has caused widespread disquiet in the scientific community.
In the latest research, a team from the Institute of Neuroscience at the Chinese Academy of Sciences used a genetic editing tool known as CRISPR/ Cas9 to knock out a gene known as BMAL1 from healthy embryos, according to paper published in the National Science Review on Thursday.
The absence of the BMAL1 gene will affect the operation of the animals’ biological clocks, and could induce a wide range of diseases, sleep problems, nighttime hyperactivity, hormonal disorders, depression and even schizophrenia. The researchers have already bred a group of gene-edited monkeys and the latest experiment involved cloning an adult male that had displayed the most severe symptoms.
“Our approach is to select one monkey that exhibits the correct gene-editing and most severe disease phenotypes as the donor monkey for cloning,” Sun Qiang, the scientist who led the study, said in a press statement.
China is at present the only country that has the technology to clone a primate, announcing the birth of two healthy cloned monkeys last year. For decades, researchers around the world had struggled to achieve this scientific know-how because some proteins were easily damaged in the cloning process.
The damaged proteins affected chromosomes’ ability to divide, which meant the fetus always died at the later stage of development. This continued until last year’s breakthrough, which used technology that remains a secret. In the latest study, Sun’s team injected the nucleus from a genetically altered adult male into an egg and planted the fertilised embryo in the womb of a surrogate mother.
More than 300 embryos were created this way, but only five fully developed.
