This study is an investigator initiated study to evaluate the safety, tolerability, and efficacy of OTOV101N+OTOV101C injection in treating patients with OTOF mutation-related deafness. The enrolled subjects who meet the inclusion and exclusion criteria will receive the gene therapy of OTOV101N+OTOV101C injection via intracochlear injection. All participants will return to the hospital for safety and efficacy evaluations at predetermined time points defined by protocol during the study (Week 1 ± 1 Day, Week 2 ± 3 Days, Week 3 ± 3 Days, Month 1 ± 3 Days, Month 2 ± 3 Days, Month 4 ± 6 Days, Month 6 ± 6 Days, Month 9 ± 6 Days, Month 12 ± 6 Days/EOS (end of study)/unscheduled visit).

This study is an investigator initiated study to evaluate the safety, tolerability, and efficacy of OTOV101N+OTOV101C injection in treating patients with OTOF mutation-related deafness.

Subjects who are successfully enrolled will visit the hospital on Day -3 to initiate the glucocorticoid treatment, then be hospitalized on Day -3~-1 to prepare for inner ear gene therapy. On the day of surgery (Day 0), subjects will undergo intracochlear injection of gene therapy products after skin preparation and disinfection of the surgical area and general anesthesia. The round window will be exposed through the tympanic membrane route. Each subject will receive adeno-associated virus (AAV) injection at a dose of 15~30μL of each AAV, mixed at 1: 1 ratio with total volume of 30~60 μL/ear. For subjects without any cochlear implantation, bilateral or unilateral intracochlear injection could be conducted as decided by investigators. For intracochlear injection, the investigators will decide if the second intracochlear injection should be conducted based on dose of the first injection by considering anatomical structure of artificial cochlea and drug loss. The timing of the second injection will be decided by recovery status of the first injection. Subjects will be in hospital for 3 days for observation after receiving the intracochlear injection or follow the routine hospitalization timing of diagnosis/treatment of site, then be discharged after recovery from the surgical operation and receive 1 year follow-up visits.

All subjects will return to the hospital (except in case of non-resistance) for safety and efficacy assessments during the study at the established time points in the protocol (Week 1 ± 1 Day, Week 2 ± 3 Days, Week 3 ± 3 Days, Month 1 ± 3 Days, Month 2 ± 3 Days, Month 4 ± 6 Days, Month 6 ±6 Days, Month 9 ± 6 Days, Month 12 ± 6 Days/EOS (end of study)/Unscheduled) unless encountering force majeure.

Inclusion Criteria:

1. Age ≥ 1 years old at the time of signing the informed consent form (ICF); both male and female are eligible.

2. Diagnostic criteria for OTOF-related hearing loss are:

   1. The hearing test and auditory brainstem response (ABR) examination show the presence of hearing loss (based on the testing report conducted within one month prior to signing the informed consent form).
   2. Genetic testing confirms the presence of OTOF gene homozygous or compound heterozygous mutations.

3. Hearing loss: severe (65 dB ≤ hearing threshold < 80 dB) or profound (80 dB ≤ hearing threshold < 95 dB) or total (hearing threshold ≥ 95 dB) hearing loss in both ears (If the testing result of ABR is "waveform is not obtained", the subjects with bilateral hearing threshold <65 dB will be enrolled as determined by the investigator).

4. Vital signs, physical examination, laboratory tests (including whole blood count, blood biochemistry, urinalysis, coagulation function, etc.), and 12-lead electrocardiogram are all normal, or any abnormalities judged by the investigator are clinically non-significant.

5. The subjects and their guardians sign the informed consent form.

Exclusion Criteria:

1. Subjects who have had a severe allergic reaction (NCICTCAE5.0 ≥ 3 Grade) to any drug or its components used in this study in the past;
2. Subjects who have received any gene therapy in the past, or have high levels of neutralizing antibodies (>1:128) in their blood;
3. Subjects who have systemic diseases or are receiving related treatments that may affect hearing or surgical operations;
4. Subjects who cannot tolerate anesthesia;
5. Subjects with inner ear malformations;
6. Subjects who have undergone bilateral cochlear implantation or have a history of major inner ear surgery (as determined by the investigator)(not include unilateral cochlear implantation);
7. Subjects with other genetic mutations causing deafness that may affect the effectiveness of OTOF gene therapy;
8. Subjects with Meniere's disease;
9. Subjects who routinely use ototoxic drugs for other medical conditions;
10. Subjects with congenital deafness caused by non-genetic factors related to birth;
11. Subjects who are currently receiving or may receive immunosuppressive therapy other than this study;
12. Subjects who are allergic or intolerant to glucocorticoid treatment;
13. Subjects with a history of malignant tumors or meningitis;
14. Subjects with a persistent or active infection, positive for hepatitis B surface antigen (HBsAg) with peripheral blood HBV DNA titers higher than the detection limit, positive for hepatitis C virus (HCV) antibodies with peripheral blood HCV RNA titers higher than the detection limit, positive for human immunodeficiency virus (HIV) antibodies, or with other immune deficiency diseases, or positive for syphilis;
15. Subjects of childbearing potential who refuse to take effective contraceptive measures (hormonal or barrier methods or abstinence) from the time of signing the informed consent form until 12 months after receiving AAV injection;
16. Female subjects of childbearing age who have a positive blood pregnancy test result, or are currently pregnant or breastfeeding;
17. Subjects who have participated in any other clinical trial and have received treatment or medication within 4 weeks prior to the first administration (excluding non-interventional studies);
18. Subjects who are unwilling or unable to comply with this study protocol;
19. Subjects whom the investigator believes are unable to participate in this study due to any medical condition or who are unable to complete the follow-up study.