EXOSC9 and Cerebellar hypoplasia: The phenotype of the exosc9 morphants and crispants was also similar to that observed in exosc3, exosc8, and rbm7 morphant zebrafish.16, 17, 19 Interestingly, other zebrafish models of cerebellar hypoplasia and atrophy caused by abnormal RNA processing have a phenotype similar to that of the exosc9 downregulated zebrafish.