COL1A1 and Interstitial cardiac fibrosis: qRT-PCR demonstrated decreased mRNA levels of collagen type I (Col1a1) and periostin (Postn), the mRNA levels of fibrosis markers, in the myocardium of R141W + PspCas13b mice compared with R141W mice (Fig. 5L, M), indicating the efficacy of PspCas13b treatment in alleviating cardiac interstitial fibrosis in R141W mice.