Chinese researchers genetically modify human embryos to make them HIV resistant

According to Nature, their paper represents the second published claim of gene editing in human embryos, the first being an attempt to modify a gene linked to blood disease.

Stem-cell scientist Yong Fan, who works at Guangzhou Medical University in China, led a team of researchers who collected 213 non-viable fertilised human eggs between April and September 2014.

These eggs were deemed non-viable because they all had an extra set of chromosomes.

Fan's team used CRISPR–Cas9 genome editing to give some of the embryos a mutation that cripples the immune cell gene CCR5, turning it into CCR5Δ32.

People who have that variant of the gene are resistant to HIV because it keeps the virus from entering their T cells.

The research is at a very early stage - not all of the embryos maintained the mutation, and others developed different mutations.

Despite their success the researchers have cautioned on the ethics of editing the human germ line right now, saying “We believe that any attempt to generate genetically modified humans through the modification of early embryos needs to be strictly prohibited until we can resolve both ethical and scientific issues.”