A recent study published in Science (Matharu et al., 2019) safely targeted the non-coding genomic region of Sim1 and MC4R with rAAV packed with CRISPRa, and successfully rescued the obesity syndrome caused by haploinsufficiency in a murine model, which shed light on their potential therapeutic applications in the future (Matharu et al., 2019). This evidence concerns the gene SIM1 and obesity due to melanocortin 4 receptor deficiency.