Improved SmOPT U7 guide RNAs achieve high levels of RNA editing in Hurler syndrome mice.

A mouse model of Hurler syndrome was successfully treated using improved guide RNAs possessing an engineered U7 snRNA hairpin and promoter for RNA base editing using the endogenous ADAR deaminase. mIDUA-W392X mice were injected retro-orbitally with 2E12 AAV.PHPeB expressing an antisense Hurler guide RNA or a Scramble guide RNA negative control. mIDUA-W392X mice injected with saline only or wild type C57BL/6 mice were also included as controls. Brain tissue (anterior cerebral cortex) was harvested 28 days later; RNA was reverse-transcribed and sequenced to quantify A-to-G RNA editing of the target mIDUA-W392X mutation.