ABSTRACT/PROJECT SUMMARY
Impressive advances in gene discovery in the auditory system have occurred in the last decades, making specific
targeted approaches for therapeutics realistic goals of great interest in the field of hearing and deafness. Hearing
loss (HL) is an increasingly significant health problem in populations worldwide, with a substantial proportion due
to genetic causes. Given the health burden and ongoing rapid discoveries, it is now essential to pursue new
strategies for specific early interventions that could prevent or mitigate severity and progression of HL. One such
disorder is DFNA9, an adult-onset sensorineural HL with balance dysfunction, caused by mutations in COCH,
encoding cochlin, the most abundantly detected protein in the inner ear. This disease model is similar to and
representative of the majority of genetic HL disorders with a dominant mode of inheritance and with a deleterious
gain-of-function of the mutant protein.
Aims 1 and 2 of this proposal involve utilization of the powerful and versatile CRISPR-Cas9 gene editing
technology for specific targeting and disruption of the dominant missense pathogenic COCH variants p.G88E
and p.A449T. We will utilize human fibroblasts from patients with these two variants, and derived pluripotent
stem cells and organoids. These biological resources will serve as tools for the development of effective methods
for allele-specific gene disruption of the COCH pathogenic variants, while leaving the normal allele intact and
functional. The organoids will be assessed as a possible in vitro system for elucidating the biology of COCH
aggregates pathognomonic of DFNA9 temporal bones. Furthermore, we will utilize two Coch knock-in (KI) mouse
models with these variants for implementation of somatic tissue gene targeting in the inner ear. These
approaches will establish methodologies for gene editing not only for DFNA9, but also for a broader category of
other HL disorders with a dominant gain-of-function mechanism of pathology, with the ultimate goal of translation
to clinical trials and therapeutic intervention.