A new scientific milestone thanks to the now famous genetic cutter technique, CRISPR. For the first time in history, an international team of scientists (from China, South Korea and the USA) has managed to correct in human embryos , using the CRISPR Cas9 gene editing tool, a mutation that causes a serious alteration: the hypertrophic cardiomyopathy . The study has been published in the journal Nature.
The gene editor corrected the mutation in about 72% of the 100 embryos tested, a much higher repair rate than expected.
Experts have succeeded in correcting in human embryos the mutation of a gene (MYBPC3) associated with the hereditary disease of hypertrophic cardiomyopathy, which affects around 1 in every 500 people in the world and which can cause sudden death in young athletes.
Researchers in other countries have edited human embryos to learn more about early human development or to answer other questions, but Shoukhrat Mitalipov and his colleagues explicitly exploited the CRISPR Cas9 technique in experiments to improve the safety and efficiency of gene editing for eventual clinical trials (something illegal in Spain), which would imply, in the future, implanting edited embryos in the uterus of women to facilitate pregnancy.
Specifically, the scientists worked in vitro with 142 human embryos in initial stages of development (oocyte, blastocyst) and from healthy women, embryos that were never implanted. They managed to fertilize 142 eggs with sperm from a single donor, a man who carried a heterozygous mutation in the MYBPC3 gene , that is, with a dominant and a correct mutated copy. Thus, without any intervention, 50% of the fertilized oocytes would be free of the mutation.
“ Each generation would carry out this repair because we have eliminated the variant of the gene that causes the disease from the family lineage. Using this technique it is possible to reduce the burden of this hereditary disease in the family and eventually in the human population “ , highlights Mitalipov.
By applying the CRISPR Cas9 technique, the experts managed to cut the sequence of the mutant gene and, in most cases, the DNA break was efficiently repaired using the non-mutated copy of the donor gene itself as a mirror. achieving that more than two thirds of the target embryos contained the two error-free copies of the gene. None of the embryos tested showed signs that Cas9 was cutting where it shouldn’t. Thus, the CRISPR Cas9 technique increased the probability of inheriting the correct gene from 50% to 72.4%.
This method could potentially be applied together with other techniques to correct the thousands of genetic alterations that affect millions of people around the world, so that they do not transmit them to their offspring.
The study is moving towards using gene editing to prevent genetic diseases, but there is still a long way to go before clinical trials can begin: “We have to be sure that this can be done effectively,” he says. Janet Rossant, a developmental biologist at The Hospital for Sick Children and the University of Toronto, Canada.
Reference: H. Ma et al “Correction of a pathogenic gene mutation in human embryos.” Nature, August 2, 2017. Doi: 10.1038 / nature23305.
