Scheme for ribozyme-mediated repair of mutant cClC-1 mRNA. The ribozyme (red) contains the IGS, which base pairs to a complementary site on the mRNA target (black) upstream of the T268M mutation (×). The ribozyme catalyzes the cleavage of T268M mRNA and then the ligation of the remaining target sequence and the wild-type 3′ exon sequence (blue), thus restoring the correct translational reading frame of cClC-1. The circled region is expanded to show the IGS, P10 helix, and antisense region interactions. Underlined bases indicate the sequence tag of silent mutations.