FMR1 and fragile X syndrome: Based on the observation that fmrp knockdown zebrafish embryos exhibited increased anxiety, irritability, and cognitive impairment at 7 dpf (days post-fertilization), researchers concluded that this was an effective DNAzyme-based model for fragile X syndrome, which was associated with impaired craniofacial development and ASD-like behaviors (Medishetti et al., 2020).