WIKIMEDIA, ERIC BAJARTA female cynomolgus monkey born with mutations in her methyl-CpG binding protein 2 gene (MECP2) represents the first non-human primate model produced through transcription activator-like effector nucleases (TALENs), a gene-editing technique. The results, published February 13 in Cell Stem Cell, follow on the heels of a study demonstrating the ability of the CRISPR/Cas9 method to produce genomically edited monkeys.
Up until these two latest developments, transgenic monkeys had only come about through virus-mediated gene transfer. TALENs bind to and snip DNA at a specified point in the genome, allowing for targeted mutagenesis. In this case, researchers designed TALEN sequences to introduce mutations in MECP2 and delivered them into monkey zygotes. Several pregnancies failed, but one female monkey born with the mutations is now several months old.
Girls with Rett syndrome—which only affects females—develop motor and speech problems and autism-like characteristics. There is currently no cure. In the monkey, MECP2 mutations were present in the placenta, umbilical cord, and skin. “So far we have not observed any behavioral deficits in this female monkey,” the authors wrote in their report. The symptoms of Rett syndrome don’t appear in humans until six to 18 months old. “It is possible that a longer time will be needed for detection of the phenotype,” they added.