Mice could slowly be replaced with monkeys as the prime animal subjects for human illness research. Scientists in China have successfully bred the first monkeys with targeted genetic mutations, which could lead to primates modeling sicknesses found in humans.

The team from Model Animal Research Center of Nanjing University led by geneticist Xingxu Huang first targeted three specific genes in a monkey cell line in the experiment, and were able to disrupt them about 10 to 25 percent of the time. They then targeted genes in 180 single-cell monkey embryos, and implanted 83 of them in living mothers. Those implantations yielded ten pregnancies — and only one birth. It was not an easy task, but the newborn twin female primates are a hopeful first step toward recreating human diseases in monkeys.

The genetic mutations are not specific diseases, but they control metabolism and the immune system

Until now, mice have been the main animal model for human illness research. Scientists have developed a method using spontaneous DNA swapping that allows them to introduce mutations into the mice easily as they reproduce. This method doesn't work in animals that reproduce slowly, like monkeys, so scientists have had to rely on viral techniques that produce unpredictable results. While the custom genetic mutations in these newborn monkeys are not specific diseases, they are associated with human conditions: one helps regulate metabolism and the other is involved in maintaining a healthy immune system.

Even if it's still in the early stages, this brings researchers one step closer to an animal model that more accurately resembles humans for testing diseases and treatments. Primates are genetically more similar to humans than mice are, so using them to model diseases could yield more accurate results. Some are saying this could lead to recreating human diseases like Alzheimer's and Parkinson's in monkeys, or even altering a monkey's DNA to make it resistant to HIV. And then, of course, there are the speculations that, down the road, we could live in a Gattaca-like world full of genetically customized children that never get sick. It's a stretch, but with a breakthrough like this, it could be more feasible than we think.