A team of researchers in Japan has genetically engineered monkeys to have Parkinson’s disease.

A new approach to studying Parkinson’s disease has been announced, and it is already attracting controversy.  
New Scientist is reporting that a team in Japan has created “the world’s first monkey genetically engineered to have Parkinson’s disease.”
To achieve this outcome, researchers from the Keio University School of Medicine in Tokyo modified marmoset monkeys to have faulty versions of the SNCA gene which eventually causes the brain to be unable to direct bodily movement. 
The animals are currently three years old and have already exhibited the progression of Parkinson’s symptoms seen in humans: the monkeys started out by having problems sleeping and now, they are displaying tremors. 
While the intention is to modify these animals in order to come up with possible treatments, critics point out that diseases like Parkinson’s will likely cause them to suffer, notes The Guardian. 
The applicability of these experiments to humans has been called into question as well.