Case study of CASK. (A) Genomic organization of the cassette exon 19, complementary sequences R3 and R4, and their respective AONs (AON3 and AON4). (B) The treatment with AON3 or AON4 significantly reduces exon 19 skipping; NT (nontreated control); C (control AON); neg (negative control). (C) The scheme of a minigene expressing a fragment of the CASK gene. (D) In m3 and m4 mutants, the base pairing between R3 and R4 is disrupted by sequence reversal; in the compensatory double mutant m3m4, it is restored. (E) Exon 19 skipping in m3 and m4 is suppressed, but in m3m4 it returns to that of the WT. Statistically discernible differences at the 5%, 1%, and 0.1% significance level are denoted by *, **, and ***, respectively. Nonsignificant differences are denoted by “ns.”
