Researchers in China claim they have successfully added mutations to human embryos which make them HIV-proof.
The study, published in the Journal of Assisted Reproduction and Genetics, used human eggs that were “suitable for implantation” thanks to an extra set of chromosomes. Researchers at Guangzhou Medical University placed a naturally-occurring immune cell gene mutation into the embryos that makes them resistant to HIV, the virus that causes AIDS.
The experiment, which involved 200 one-cell embryos, resulted in 4 modified embryos. 
It is the second published claim of editing genes of human embryos. In early 2015, Chinese researchers announced they had used a gene-editing technique called CRISPR to modify an aberrant gene responsible for causing beta thalassaemia, an inherited, life-threatening blood disorder.
The researchers wrote:
“The purpose of this study was to evaluate the technology and establish principles for the introduction of precise genetic modifications in early human embryos.
We advocate preventing any application of genome editing on the human germline until after a rigorous and thorough evaluation and discussion are undertaken by the global research and ethics communities.” 
Yong Fan, a researcher at Guangzhou Medical University, said that “it is foreseeable that a genetically modified human could be generated.“
Germline editing is a highly controversial practice that forever alters the genes of children and future generations. The technology allows scientists to locate an unwanted DNA strand in a person’s genome, delete it, and replace it with a new, genetically engineered strand. The ethics of genetically modifying humans are very much a topic of intense date. Late last year, a group of scientists, The Center for Genetics and Society, and the activist group Friends of the Earth, called for a ban on the practice.
Two days later, the message of dozens of scientists and ethicists who gathered in Washington, DC for the International Summit on Human Gene Editing was: “Steer clear of creating GMO babies.” The scientists and ethicists concluded at the end of the 3-day discussion that the world was not yet ready for germline editing.
Supporters of the practice say it could permanently eradicate interminable diseases, while opponents warn germline editing is a step closer to the development of “designer babies,” which would allow parents to choose the gender and physical and intellectual attributes of their offspring. This, many fear, could lead to people being born with an unfair advantage over individuals created the “natural” way.
And though it may sound like the stuff of science fiction, it’s possible that gene editing could be used for ‘evil.’
In February of this year, James Clapper, U.S. Director of National Intelligence, wrote in his annual Worldwide Threat Assessment report that genetic modification using CRISPR and similar technologies could be used as a “weapon of mass destruction and proliferation.” Clapper wrote:
“Given the broad distribution, low cost, and accelerated pace of development of this dual-use technology, its deliberate or unintentional misuse might lead to far-reaching economic and national security implications.”
Despite the calls to slow or stop germline editing on humans, some scientists are determined to push the envelope, especially in China, but also in the UK. In early February, British researcher Kathy Niakin got the go-ahead from the Human Fertilization and Embryology Authority (HFEA) to carry out her own genetic engineering experiments on human embryos.
Niakin and her colleagues at the Francis Crick Institute plan to deactivate genes in leftover embryos from in-vitro fertilization clinics to find out if it dissuades development. The embryos must be destroyed after 14 days and may only be used for basic research, not implantation.
 Daily Mail