Authors: Avery Zentner. Mentors: Hung Yu Shih. Insitution: Utah Tech University. 4H Leukodystrophy (4H) is an early-onset rare genetic disease, which causes myelination loss in the nervous system without a current cure. 4H patients exhibit different phenotypic spectrums of hypomyelination, hypodontia, and hypogonadotropic hypogonadism. Mutations in polr3a, polr3b, polr3k, and polr1c, which encode the RNA polymerase III subunits, could lead to 4H development. To date, there are no available animal models to bona fide the clinical symptoms of human patients, limiting the therapeutic development of 4H. Zebrafish, Danio rerio, might be an ideal model for 4H. Zebrafish have been widely used for human disease models and drug development. This project aims to establish and characterize the zebrafish 4H model by knocking out the polr3a with the CRISPR/Cas9 approach. The polr3a-Crispants significantly increased the mortality rate as compared to wild-type embryos. Behavior analysis showed the polr3a-Crispants reduced swimming ability upon light stimulation, which might reflect the clinical ataxia or vision problem. Quantitative PCR (qPCR) analysis showed a significant reduction in myelin-associated genes. These results suggest the polr3a knockout could mimic the clinical symptoms. Future studies will characterize the detailed neurological defects and the underlying mechanisms of 4H development and progression. Moreover, we will utilize the 4H zebrafish model for therapeutic drug screening.
