# Development of Gene Therapy for Hereditary Deafness using Rational Protein Engineering

> **NIH NIH R01** · MASSACHUSETTS EYE AND EAR INFIRMARY · 2024 · $614,272

## Abstract

PROJECT SUMMARY
Deafness and blindness are two of the most common and most devastating neurological disorders. Seldom
fatal, they separate patients from the world they live in and the people they love, for a lifetime. In many cases,
combined deafness and blindness result from a single gene defect, usually with a mutant gene copy inherited
from both parents. Usher syndrome is a devastating hereditary deafness and blindness caused by mutation of
any of nine genes. One gene, PCDH15, when mutated, causes Usher syndrome type 1F, manifesting as
profound congenital deafness, balance disorder and progressive blindness. There is no treatment. New methods
are rapidly being developed for gene therapy to treat monogenic disorders, methods that change patient lives.
Here, we propose to develop a gene therapy strategy for Usher Syndrome Type 1F and to initiate its path to the
clinic to treat different pathologies of the disease.
Adeno-associated virus (AAV) vectors have been found to be efficient and effective for gene therapy in the inner
ear and their application in development of gene addition therapies to treat Usher syndrome type 1F is an
attractive approach. However, the PCDH15 coding sequence of almost 6 kb is too large to fit in AAV, which has
a capacity of ~4.7 kb. Most of PCDH15 resembles a “bead chain” structure of 11 beads, with binding domains
at N- and C-terminal ends. We have developed novel “mini-PCDH15” constructs that retain the binding domains
but lack 4-5 beads, and that consequently fit in AAV vectors. They show normal binding in vitro; at least two
rescue hearing in our Pcdh15-knockout mouse model. We will use these and new mini-PCDH15 constructs to
rescue hearing and vestibular function in Pcdh15-knockout mice. We will also employ in silico and in vitro
structural biology and protein chemistry to carefully characterize each successful mini-PCDH15, and use that for
iterative optimization of engineered mini-PCDH15s. Finally, we will test the best performing mini-PCDH15 for
localization and toxicity in non-human primate ear as part of their preclinical evaluation.
Because mechanical stress on PCDH15 is greater in the inner ear than in the eye, the engineered mini-PCDH15
constructs that successfully rescue hearing or balance will also have the potential to halt or even reverse the
progressive vision loss in patients. In addition, methods we develop in this study using a rational, iterative,
structure-based mini-gene approach to develop Usher 1F therapy will be applicable to many other deafness
genes with coding sequences that do not fit in AAV.
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## Key facts

- **NIH application ID:** 10848426
- **Project number:** 5R01DC020190-03
- **Recipient organization:** MASSACHUSETTS EYE AND EAR INFIRMARY
- **Principal Investigator:** DAVID P COREY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $614,272
- **Award type:** 5
- **Project period:** 2022-06-17 → 2027-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10848426

## Citation

> US National Institutes of Health, RePORTER application 10848426, Development of Gene Therapy for Hereditary Deafness using Rational Protein Engineering (5R01DC020190-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10848426. Licensed CC0.

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