Rare hemoglobin disorders remain major target diseases to be corrected with genome editing systems

Recently, Sangamo Biosciences received green light from FDA to start clinical trials on beta-thalassemia. In their approach, finc-finger nucleases shall disrupt transcriptional regulators to switch the production from mutated adult hemoglobin back to normal fetal hemoglobin. Now, another company, Editas Medicine reported successful in vivo gene repair for sickle cell anemia at the Keystone Symposium for Genomic Instability and DNA Repair in Whistler, British Columbia, Canada. This hereditary hemoglobinopathy is characterized by a mutation in the hemoglobin beta (HBB) gene leading to abnormal red blood cell morphology under certain circumstances. The presented mechanism for gene repair is thought to be gene conversion, i.e. self-repair of the CRISPR targeted allele utilizing a different, but closely related gene as a repair template. The efficiency and precise mechanism remains a question. “These data suggest gene conversion as a possible new approach to genomic repair for certain kinds of genetic mutations,” said Katrine Bosley, chief executive officer, Editas Medicine. “While the results are early and further work is needed to see if this approach could be used therapeutically, the data exemplify Editas’ commitment to explore and develop the full potential of genome editing to treat a broad range of genetically driven diseases.”
Source: http://www.editasmedicine.com/documents/Editas%20Keystone%20Data%20PR%20030115%20FINAL%20.pdf