Comparison of GALC gene editing efficiency between ABE8e and ABE8eWQ in a mouse model of Krabbe’s disease

Abstract

Krabbe disease is an autosomal recessive disease caused by the lack of GALC enzyme, which is required to hydrolyze certain toxic galactolipids. This leukodystrophy affects both the central nervous system and the peripheral nervous system. So far, therapeutic agents have been developed to treat Krabbe disease by injecting normal GALC gene. But we treated this disease by removing the genetic cause in vivo using adenine base editing (ABE). In this study, using two types of adenine base editor, ABE8e and ABE8eWQ, we analyze not only their gene editing efficiency of target adenine, but also level of non-specific genetic alteration because these traits were directly related to the biological safety. ABE8eWQ was developed based on ABE8e to create a target-specific gene editor with increased editing efficiency of target adenine and reduced off-target effects. Therefore, experiment was conducted to confirm that ABE8eWQ has fewer side effects in vivo. Gene editing efficiency of bystanders which are non-target adenines was significantly lower in ABE8eWQ compared to ABE8e. ABE-injected disease group, however, whether it was ABE8e or ABE8eWQ, demonstrated increased body and brain weight, higher behavioral test scores, decreased tremor and increased lifespan. Histological analysis of their brain also revealed better appearing myelin. Our study shows that both of ABEs, with no difference in side effects, helped alleviate overall disease symptoms of Krabbe disease.