Human germline engineering

rdf:langString Human germline engineering

rdf:langString Human germline engineering is the process by which the genome of an individual is edited in such a way that the change is heritable. This is achieved through genetic alterations within the germ cells, or the reproductive cells, such as the egg and sperm. Human germline engineering is a type of genetic modification that directly manipulates the genome using molecular engineering techniques. Aside from germline engineering, genetic modification can be applied in another way, somatic genetic modification. Somatic gene modification consists of altering somatic cells, which are all cells in the body that are not involved in reproduction. While somatic gene therapy does change the genome of the targeted cells, these cells are not within the germline, so the alterations are not heritable and cannot be passed on to the next generation. For safety, ethical, and social reasons, there is broad agreement among the scientific community and the public that germline editing for reproduction is a red line that should not be crossed at this point in time. There are differing public sentiments, however, on whether it may be performed in the future depending on if the intent would be therapeutic or non-therapeutic. Using germline editing for reproduction is prohibited by law in more than 70 countries and by a binding international treaty of the Council of Europe. However, in November 2015, a group of Chinese scientists used the gene-editing technique CRISPR/Cas9 to edit single-celled, non-viable embryos to see the effectiveness of this technique. This attempt was rather unsuccessful; only a small fraction of the embryos successfully incorporated the new genetic material and many of the embryos contained a large number of random mutations. The non-viable embryos that were used contained an extra set of chromosomes, which may have been problematic. In 2016, another similar study was performed in China which also used non-viable embryos with extra sets of chromosomes. This study showed very similar results to the first; there were successful integrations of the desired gene, yet the majority of the attempts failed, or produced undesirable mutations. In an experiment in August 2017, the correction of the heterozygous MYBPC3 mutation associated with hypertrophic cardiomyopathy in human embryos was attempted with precise CRISPR–Cas9 targeting. 52% of human embryos were successfully edited to retain only the wild type normal copy of MYBPC3 gene, the rest of the embryos were mosaic, where some cells in the zygote contained the normal gene copy and some contained the mutation. In November 2018, researcher He Jiankui claimed that he had created the first human genetically edited babies, known by their pseudonyms, Lulu and Nana. In May 2019, lawyers in China reported, in light of the purported creation by He Jiankui of the first gene-edited humans, the drafting of regulations that anyone manipulating the human genome by gene-editing techniques, like CRISPR, would be held responsible for any related adverse consequences.