Hereditary hearing loss: from gene to mechanism

• Applicant: Privatdozentin Dr. Barbara Vona, Ph.D.
• Subject Area: Otolaryngology, Phoniatrics and Audiology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469177153

Hearing loss is one of the most genetically heterogeneous disorders in humans. It affects roughly 1 per every 500 to 1,000 newborns and has an increasing prevalence throughout the lifespan. Identification of causal genes has greatly accelerated with advancements in sequencing technologies. However, an estimated 600 genes remain to be identified and functionally characterized – an aspect that lags far behind the identification of variants. This proposal builds off already established resources from a large, ethnically diverse genomics study that ascertained families with undiagnosed forms of hereditary hearing loss for gene discovery. These genomics studies identified families with variants in two candidate genes, FBXO30 and TOGARAM2, that are the focus of this project. The work plan engages multiple approaches to untangle a proposed function and mechanism for disruption to FBXO30 and TOGARAM2. Firstly, CRISPR/Cas9 gene-editing of FBXO30 in cell lines to knock-out and knock-in patient-specific variants will be subjected to global quantitative proteomic analysis. Cellular phenotyping of the mitotic spindle and proliferation assays will be performed. These experiments will provide first insights into differentially regulated proteins and assess a potential role for FBXO30 in cell cycle oscillation. Secondly, protein complex analysis studies involving FBXO30 and TOGARAM2 will uncover candidate functional interaction partners and potentially uncover additional pathways for both proteins. Thirdly, a CRISPR/Cas9 Togaram2 knock-out mouse will be generated and phenotyped through extensive auditory testing to allow studies to identify morphological changes to the organ of Corti. Spatiotemporal expression studies of the mouse inner ear for both FBXO30 and TOGARAM2 are planned. Lastly, through the analysis of genome data from new undiagnosed patients, additional families may be identified that would greatly expand insights into the clinical course and disease outcomes of patients affected with these ultra-rare hereditary diseases. The generated data will be submitted to public databases and repositories. The results of this study are expected to provide new insights into cellular and molecular pathology, improve molecular diagnostics, and open a path to enable the evaluation of personalized medicine options for two ultra-rare forms of hereditary hearing loss.

• DFG Programme: Research Grants
• International Connection: Italy, USA
• Cooperation Partners: Professor Dr. Marco Sandri, Ph.D.; Professor Dr. Mustafa Tekin
• Co-Investigator: Professor Dr. Sven Nahnsen