That the base editors can beused for correction of single base genetic defects has been demonstrated byusing several model systems including mouse, zebrafish and Xenomus.
Efficiency and effectiveness of these base editors hasalso been demonstrated using human cell lines and zygotes/embryos. Forinstance, in a seminal recent study, using mouse/human cells, it was shown that the mutations (C®Tor G®A) associated with Alzheimer’s (APOE4, Cys158Arg mutation: potent Alzheimer’s riskfactor), and somecancers (p53 Tyr163Cys mutation, associated with cancer) can be treated throughbase editing15. StandardCRISPRCas9 method of genome editing may not help in many of these cases, but asafe and reliable delivery of base editors (BEs) in the form of molecular machine can besuccessfully used with no side effects. In this connection, concerns if any,are being addressed by researchers around the world, so that in the near futuregen therapy based on base-editors will become available, although it may taketime for them to reach the doctors clinics. Several reports are available, wherecorrections of individual genes has been demonstrated even at the organismallevels in model systems like mouse, zebrafish and Xenopus, where altered embryoswere transplanted in pesudopegnant surrogate mothers and mutant offspringobtained26,27.
The gene tyrencoding tyrosine pigment causing albinism has been successfully used inseveral of these studies. In China, a singlebase mutation for a blood disorder was corrected in human embryos using amolecular machine in the form of base editor, although the embryos were notallowed to develop further.