JSU Student Symposium 2022



Faculty Mentor

Ashley Turner, Biology



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1:45-1:55pm | Houston Cole Library, 11th Floor


Congenital stationary night blindness (CSNB) is a disorder of the eye that impacts the ability to see in low to no light conditions. It occurs in horses and humans. TRPM1 encodes for a member of the transient receptor potential melastatin subfamily of transient receptor potential ion channels. Mutations in TRPM1 have been identified by previous researchers in horses with leopard complex pattern (LCP) suffering also from CSNB. Phenotypic changes in these horses are a loss of spotted coat pattern. An attempt was made to locate variants of uncertain significance (VUS) in TRPM1 that had been previously identified in horses with CSNB and LCP. However, there is a lack of available DNA sequencing information for this gene in impacted horses across equine studies. So, we turned to VUS identified in human patients with CSNB to examine actual VUS identified among another vertebrate causing the same condition. We examined evolutionary conservation analysis of missense TRPM1 variants across horses (E. caballus), humans (H. sapiens), and nematodes (C. elegans). Using Benchling, the human TRPM1 gene, horse TRPM1 gene, and nematode gon-2 gene were imported to examine conservation of 31 VUS through multiple sequence alignments and 3 were conserved across all 3 species. These VUS were at the following locations in human: E1324K, H1195R, and I875V. Conducting a gene mutational analysis revealed the variants at H1195R and I875V were most likely to be pathogenic due to their positioning next to pathogenic or likely pathogenic variants reported through ClinVar. Through Poly-Phen 2 analysis, variant I875V was predicted to be the most damaging and likely pathogenic. The HumDiv results predicted this variant to be possibly damaging with a score of 0.775, and the HumVar model predicted the variant to be benign with a score of 0.230. Primers were designed to amplify this VUS region in C. elegans using polymerase chain reaction (PCR) and gel electrophoresis. Future experimentation includes designing a CRISPR RNA guide to target gon-2, microinjection of CRISPR-Cas9 reagents to generate the VUS-gon-2 C. elegans model, and screening and phenotyping of the identified VUS model. If results are positive and the VUS does impact structure and function of gon-2, then it is expected to impact gonadal and vulva development in the nematode. This study will provide in vivo assessment of this CSNB-associated VUS shedding light on its clinical significance for humans and horses.


student research, biology


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Genetic Assessment of Congenital Stationary Night Blindness-associated TRPM1 Variants of Uncertain Significance in C. Elegans

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