| Usher subtype | Sensorineural hearing loss (onset / severity / progression) | Retinitis pigmentosa / visual features | Vestibular function | Age of onset summary | Key distinguishing features | Suggested HPO terms |
|---|---|---|---|---|---|---|
| **USH1** | **Congenital, severe-to-profound, usually prelingual** SNHL; often described as non-progressive or minimally progressive in classic presentations (pqac-00000003, pqac-00000009) | **Prepubertal / first-decade onset** rod-cone dystrophy or RP; progressive night blindness, peripheral visual field constriction, later severe visual impairment/legal blindness often by the fourth decade in classic descriptions (pqac-00000003, pqac-00000009) | **Vestibular areflexia / marked hypofunction** is typical; delayed motor milestones, many children walking after 18 months (pqac-00000003, pqac-00000009) | Hearing: birth; Vision: first decade / prepubertal; Balance: infancy (pqac-00000003, pqac-00000009) | Most severe classic form; congenital deafness plus early RP and absent vestibular function; speech may not develop without early auditory intervention such as cochlear implantation (pqac-00000003, pqac-00000006) | HP:0000407 Sensorineural hearing impairment; HP:0000369 Progressive deafness; HP:0000510 Visual impairment; HP:0000556 Retinal dystrophy; HP:0000662 Night blindness; HP:0001123 Constriction of visual field; HP:0001756 Vestibular dysfunction; HP:0002194 Delayed gross motor development |
| **USH2** | **Congenital/early-onset, moderate-to-severe**, classically down-sloping high-frequency SNHL; speech generally intelligible; once considered stable, but multiple studies report progression, especially at high frequencies (pqac-00000003, pqac-00000007, pqac-00000009) | **Second-decade onset** RP; progressive nyctalopia and concentric visual field loss; average diagnosis often in the third decade; cataract and cystoid macular edema are relatively common in USH cohorts (pqac-00000003, pqac-00000006, pqac-00000011) | **Usually normal vestibular function**, though some series report variable or subtle dysfunction in a subset (pqac-00000003, pqac-00000007, pqac-00000009) | Hearing: birth/early childhood; Vision: second decade; Balance: usually normal (pqac-00000003, pqac-00000007) | Most common subtype; milder auditory phenotype than USH1, later retinal disease, and absent/less prominent vestibular signs; often associated with **USH2A** (pqac-00000003, pqac-00000007, pqac-00000010) | HP:0000407 Sensorineural hearing impairment; HP:0001329 High-frequency sensorineural hearing impairment; HP:0000510 Visual impairment; HP:0000556 Retinal dystrophy; HP:0000662 Night blindness; HP:0001123 Constriction of visual field; HP:0000545 Myopia; HP:0000518 Cataract |
| **USH3** | **Postlingual, progressive, variable** SNHL; hearing may be normal or near-normal in early life, then worsens over time to severe/profound deafness in many affected individuals (pqac-00000003, pqac-00000006, pqac-00000009) | **Variable onset**, often postpubertal or in the second decade, with progressive RP causing nyctalopia and visual field constriction (pqac-00000003, pqac-00000006) | **Variable vestibular dysfunction**, present in about half of affected individuals in some summaries (pqac-00000003, pqac-00000006) | Hearing: childhood to adolescence, postlingual; Vision: variable, often second decade or later; Balance: variable onset (pqac-00000003, pqac-00000006) | Rarest classic subtype in many Western populations; characterized chiefly by **progressive** rather than congenital-fixed auditory loss and marked intrafamilial/interindividual variability (pqac-00000003, pqac-00000006, pqac-00000009) | HP:0000407 Sensorineural hearing impairment; HP:0000369 Progressive deafness; HP:0000510 Visual impairment; HP:0000556 Retinal dystrophy; HP:0000662 Night blindness; HP:0001123 Constriction of visual field; HP:0001756 Vestibular dysfunction |


*Table: This table summarizes the defining clinical phenotypes of USH1, USH2, and USH3, including hearing, retinal, and vestibular features, timing of onset, and distinguishing traits. It also provides suggested HPO terms to support phenotype annotation in a disease knowledge base.*