Usher Syndrome

Overview

Usher syndrome is a group of inherited conditions that combines sensorineural hearing loss with retinitis pigmentosa (RP), a progressive degeneration of the light-sensing retina. Vision loss commonly begins with difficulty seeing at night and shrinking side vision, and may progress to tunnel vision; some people retain central vision for much of life. The three broad clinical types differ in timing and severity: type 1 usually includes profound congenital deafness and balance problems, type 2 usually includes congenital hearing loss without major balance impairment and later-onset vision loss, and type 3 typically causes later progressive hearing and vision loss. Usher syndrome genetics (medlineplus.gov)

There is currently no approved cure that restores or permanently prevents the hearing, balance, and retinal effects of Usher syndrome. Standard care is therefore multidisciplinary and supportive: genetic diagnosis and retinal monitoring, hearing aids or cochlear implants where appropriate, communication support, low-vision rehabilitation, orientation-and-mobility training, and management of complications such as cataracts. Usher syndrome care Usher syndrome type I management (medlineplus.gov)

Scope of Recent Research (2020–present)

Research activity since 2020 has accelerated around treatments tailored to the responsible gene or mutation, particularly MYO7A-related Usher type 1B and USH2A-related type 2A. The central questions are how to deliver unusually large genes into retinal cells, correct or bypass specific mutations safely, measure slow retinal change reliably, and intervene before too many photoreceptors have died. The field has entered an important but early clinical stage: one dual-vector gene-replacement program for USH1B and one RNA-splicing program for exon 13 of USH2A are in human trials, but no intervention has yet demonstrated a durable cure for the whole syndrome. LUCE-1 trial LUNA trial (clinicaltrials.gov)

Major Breakthroughs and Emerging Therapies

The most consequential recent advance is dual-adeno-associated virus (dual-AAV) gene replacement for USH1B caused by MYO7A variants. MYO7A is too large for a conventional single AAV vector, so AAVantgarde Bio’s AAVB-081 splits the gene across two AAV8 vectors that are injected beneath the retina and recombine inside treated cells. The first-in-human LUCE-1 trial produced preliminary sponsor-reported signals of improved visual function in the first participant and acceptable short-term tolerability in the first eight treated people; these findings are encouraging but remain preliminary and are not yet proof of durable efficacy. TIGEM LUCE-1 update LUCE-1 trial (tigem.it)

RNA therapeutics are furthest advanced for a subset of USH2A disease. Ultevursen (formerly QR-421a) is an antisense oligonucleotide—an engineered short strand of RNA-like material—designed to cause cells to skip exon 13 while making USH2A messenger RNA. This may allow production of a shorter but functional usherin protein in people with disease-causing variants in that exon. In the earlier STELLAR study, 29 treated participants had a favorable safety profile, and a single injection showed trends toward stabilization of retinal structure and function compared with sham treatment; the observations require confirmation in the larger ongoing LUNA trial. Ultevursen STELLAR analysis (sepulbio.com)

Several preclinical programs address the large-gene problem more broadly. Researchers reported non-viral episomal-vector delivery of the full 15.6-kilobase USH2A coding sequence, a potential alternative to conventional AAV for genes that exceed AAV’s approximately 4.7-kilobase carrying capacity. In USH1F mouse models, dual-AAV delivery of PCDH15 produced sustained rescue of visual function, supporting the idea that split-vector strategies may be adaptable beyond MYO7A. Non-viral USH2A augmentation Dual-AAV PCDH15 therapy (pubmed.ncbi.nlm.nih.gov)

Gene editing remains experimental but has advanced substantially. A 2025 study screened base-editing approaches for 35 USH2A mutations and, in a humanized mouse model, used split-intein AAV9 delivery to restore usherin protein and correct the target nucleotide in many retinal cells. Separately, researchers used CRISPR-Cas9 approaches in patient-derived cells to correct a recurrent deep-intronic USH2A splicing defect; virus-like particles were tested as a temporary delivery method intended to avoid permanent editor expression. These are promising laboratory results, not human treatments. USH2A base-editing study CRISPR splicing-correction study (pubmed.ncbi.nlm.nih.gov)

Clinical Trials and Experimental Approaches

AAVantgarde Bio sponsors the international Phase 1/2 LUCE-1 study of subretinal AAVB-081 for MYO7A-associated USH1B retinitis pigmentosa. The registry lists an estimated enrollment of 15 participants. In July 2025, the academic developers reported that the first patient had experienced visual improvement over 12 months and that seven additional patients had been treated; mild, infrequent ocular inflammation was reportedly manageable with corticosteroids. Because those outcomes were disclosed by the developer while the study remains ongoing, they should be interpreted as early safety and signal-finding data rather than established clinical benefit. LUCE-1 trial TIGEM LUCE-1 update (clinicaltrials.gov)

Laboratoires Théa’s Sepul Bio unit sponsors LUNA, a recruiting Phase 2b, randomized, double-masked, sham-controlled study of intravitreal ultevursen for RP caused by exon 13 mutations in USH2A. The study plans to enroll 81 participants, randomized two-to-one to ultevursen or sham procedures, with treatment doses at day 1 and months 6, 12, and 18. As of the ClinicalTrials.gov update posted June 18, 2026, no trial results had been posted. LUNA trial (clinicaltrials.gov)

The earlier Phase 1/2 STELLAR program provides the main available human evidence for ultevursen. Its reported trends in ellipsoid-zone preservation—a retinal imaging measure associated with surviving photoreceptors—and visual-function measures helped support advancement to LUNA, but the treatment is mutation-specific and repeated injections may be needed. Ultevursen STELLAR analysis (sepulbio.com)

Methodologies and Scientific Approaches

Usher researchers combine gene sequencing with patient-derived cell systems, animal models, and increasingly sophisticated retinal organoids—three-dimensional retinal tissue grown from induced pluripotent stem cells. In a 2023 study, fibroblasts, induced pluripotent stem cells, and retinal organoids from people with USH2A-related nonsyndromic RP or Usher syndrome showed distinct disease-related retinal features, while genetically corrected comparison cells helped establish that the observed differences were mutation-related. USH2A retinal-organoid models USH2A iPSC correction (pubmed.ncbi.nlm.nih.gov)

Therapy-development studies also use optical coherence tomography, fundus autofluorescence, visual acuity, visual-field testing, microperimetry, electroretinography, and patient-reported outcomes to identify changes in retinal structure and function. In USH2A studies, ellipsoid-zone area is emerging as a potentially useful early structural biomarker, while natural-history cohorts are being used to define progression rates and improve trial design. Ultevursen STELLAR analysis (sepulbio.com)

Leading Institutions and Funding

The clinical gene-therapy effort for USH1B is led by the Telethon Institute of Genetics and Medicine (TIGEM), the University of Campania “Luigi Vanvitelli,” and AAVantgarde Bio. AAVB-081 received U.S. FDA orphan-drug designation on October 29, 2024, although the FDA records that it is not approved for the orphan indication. FDA orphan-drug record for AAVB-081 TIGEM LUCE-1 update (accessdata.fda.gov)

Important academic contributors include Massachusetts Eye and Ear/Harvard Medical School, which led recent USH2A base-editing work; the University of Montpellier and collaborating European centers developing retinal-organoid models; and Boston Children’s Hospital, where the Usher Syndrome Society launched the Pipeline for Usher Syndrome Research (PUSH) in 2025. The Usher Syndrome Society reports committing more than $3.8 million to research and has funded projects including mini-CDH23 gene therapy and high-capacity-vector work for USH2A. In the United States, the National Eye Institute is the primary NIH institute supporting Usher syndrome research. USH2A base-editing study USH2A retinal-organoid models Usher Syndrome Society research programs NIH Usher syndrome information (pubmed.ncbi.nlm.nih.gov)

Strengths, Limitations, and Challenges

The field’s strengths are its increasingly precise genetic diagnosis, credible preclinical rescue in disease-relevant models, and the transition of both a gene-replacement strategy and an RNA-splicing strategy into clinical testing. The dual-AAV MYO7A program is especially important because it directly tests whether a large Usher gene can be reassembled effectively in human retinal cells, while ultevursen offers a less invasive intravitreal approach for a genetically defined group of USH2A patients. LUCE-1 trial LUNA trial (clinicaltrials.gov)

The limitations are equally substantial. Usher syndrome is genetically diverse, so a treatment for one gene, exon, or variant may not help most people with the condition. Many causative genes are too large for standard AAV vectors; editing systems must achieve sufficient delivery and accuracy while avoiding harmful off-target changes; and RNA splice correction is not permanent. Moreover, retinal rescue cannot automatically replace photoreceptors that have already died, and current eye-directed trials do not establish restoration of congenital hearing loss or vestibular dysfunction. Non-viral USH2A augmentation CRISPR splicing-correction study Usher syndrome genetics (pubmed.ncbi.nlm.nih.gov)

Outlook and Future Directions

As of August 8, 2026, Usher syndrome is not close to a single universal cure, but the field has moved beyond purely supportive care toward disease-modifying clinical trials. The most important near-term milestones are peer-reviewed, longer-term LUCE-1 safety and efficacy data; LUNA’s ability to show a meaningful benefit over sham treatment; validation of retinal imaging biomarkers; and confirmation that large-gene delivery or precise editing can work safely in people. A realistic first success is more likely to be preservation or partial improvement of retinal function in a defined genetic subgroup than complete restoration of hearing, balance, and vision across all forms of Usher syndrome. TIGEM LUCE-1 update LUNA trial FDA orphan-drug record for AAVB-081 (tigem.it)

References

• Usher syndrome genetics — MedlinePlus Genetics, 2025.
• Usher syndrome care — MedlinePlus, 2025.
• Usher syndrome type I management — GeneReviews®, 2026.
• LUCE-1 trial — ClinicalTrials.gov, 2026.
• LUNA trial — ClinicalTrials.gov, 2026.
• TIGEM LUCE-1 update — Telethon Institute of Genetics and Medicine, 2025.
• Ultevursen STELLAR analysis — Yang et al., 2025.
• Non-viral USH2A augmentation — Botto et al., 2023.
• Dual-AAV PCDH15 therapy — Riaz et al., 2023.
• USH2A base-editing study — Comander et al., 2025.
• CRISPR splicing-correction study — Dulla et al., 2025.
• USH2A retinal-organoid models — Sanjurjo-Soriano et al., 2023.
• USH2A iPSC correction — Liu et al., 2021.
• FDA orphan-drug record for AAVB-081 — U.S. Food and Drug Administration, 2024.
• Usher Syndrome Society research programs — Usher Syndrome Society, 2026.