| Knowledge-base field | Evidence-based summary | Suggested ontology mapping | Evidence |
|---|---|---|---|
| Disease identity | Rare inherited retinal dystrophy spanning macular dystrophy, cone dystrophy, cone–rod dystrophy and, less often, an RP-like phenotype; designated **GUCA1A-related retinopathy**. | **MONDO:0700376** | (pqac-00000000, pqac-00000001) |
| Gene/protein | **GUCA1A** encodes guanylate cyclase-activating protein 1 (**GCAP1**), a neuronal calcium sensor expressed in rod and cone photoreceptors and involved in recovery of phototransduction. | Suggested gene/protein annotations: **GUCA1A**, **GCAP1** | (pqac-00000011, pqac-00000013) |
| Inheritance | Predominantly **autosomal dominant**, caused by heterozygous germline missense variants; multigenerational disease was present in 13 of 14 families in the largest reported cohort. Penetrance is not reliably quantified, and expressivity is highly variable. | Suggested HPO: *Autosomal dominant inheritance* | (pqac-00000002, pqac-00000009, pqac-00000011) |
| Core phenotypes | Progressive bilateral central visual loss, impaired color discrimination and photophobia; central/paracentral scotomas, macular/outer-retinal atrophy and reduced cone ERG responses are typical. Rod dysfunction is usually absent or later/milder, but severe cone–rod disease occurs. | Suggested HPO: *Progressive visual loss*, *Reduced visual acuity*, *Abnormal color vision*, *Photophobia*, *Central scotoma*, *Macular atrophy*, *Cone dystrophy*, *Cone-rod dystrophy*, *Abnormal electroretinogram*, *Nystagmus* | (pqac-00000002, pqac-00000004, pqac-00000006) |
| Mechanism | Missense variants—often affecting GCAP1 EF-hand calcium-sensing regions—reduce calcium sensitivity and permit persistent retinal guanylate-cyclase activation at calcium concentrations that should inhibit it. This dysregulates cGMP and Ca²⁺ homeostasis and leads to photoreceptor dysfunction and degeneration; the final cell-death pathway is supported strongly by models but is not fully resolved in humans. | Suggested GO biological processes: *visual phototransduction*, *phototransduction recovery*, *calcium ion sensing*, *regulation of guanylate cyclase activity*, *cGMP biosynthetic process*, *calcium ion homeostasis*, *photoreceptor cell death* | (pqac-00000010, pqac-00000011, pqac-00000012, pqac-00000014) |
| Cells/anatomy | Primary targets are macular cone photoreceptors and, variably, rod photoreceptors; abnormalities begin in the outer photoreceptor/ellipsoid-zone region. RPE involvement occurs with advanced human maculopathy and in zebrafish models. Disease is generally bilateral and highly symmetric. | Suggested CL: *cone photoreceptor cell*, *rod photoreceptor cell*, *retinal pigment epithelial cell*. Suggested UBERON: *retina*, *macula*, *neural retina*, *photoreceptor outer segment*, *retinal pigment epithelium* | (pqac-00000003, pqac-00000007, pqac-00000021) |
| Diagnostics | Clinical assessment should combine visual acuity and color-vision evaluation with fundus examination, fundus autofluorescence, macular SD-OCT, visual fields and ISCEV-standard pattern/full-field ERG. Molecular confirmation can use an inherited-retinal-disease panel, WES or WGS, followed by Sanger/segregation testing and ACMG/AMP interpretation. | Suggested HPO-linked findings: *Ellipsoid-zone disruption*, *Outer retinal atrophy*, *Central scotoma*, *Reduced cone ERG response* | (pqac-00000024, pqac-00000027, pqac-00000028, pqac-00000029) |
| Prognosis | Chronic, generally progressive and nonlethal. In 19 patients, mean onset was 23 years (range 5–74), and visual acuity worsened by approximately **0.20 logMAR per decade**, although severity ranged from preserved acuity beyond age 70 to no light perception. Possible variant-specific and sex effects require confirmation. | Suggested HPO: *Variable age at onset*, *Progressive visual impairment*, *Variable expressivity* | (pqac-00000001, pqac-00000002, pqac-00000026) |
| Treatment status | No GUCA1A-specific approved disease-modifying therapy or relevant registered interventional trial was identified in the gathered evidence. Present care is supportive and rehabilitative. AAV8-delivered RNA interference delayed degeneration and improved function in mutant-GCAP1 mice, but remains preclinical and carries normal-allele suppression/off-target concerns. | Suggested NCIT intervention concepts: *Low Vision Rehabilitation*, *Genetic Counseling*, *Gene Silencing Therapy*, *Adeno-Associated Virus Vector Therapy* | (pqac-00000017, pqac-00000018, pqac-00000020) |
| Experimental models | Engineered mouse models include transgenic **Y99C**, transgenic **L151F** and knock-in **E155G**, which reproduce dominant, progressive photoreceptor dysfunction with cone-predominant degeneration. Zebrafish overexpressing human **R120L** show photoreceptor and RPE disruption. These are induced genetic models, not documented natural veterinary disease. | Suggested model annotations: *Mus musculus genetic disease model*; *Danio rerio overexpression model* | (pqac-00000017, pqac-00000019, pqac-00000021) |
| Evidence gaps | Disease-specific incidence, population prevalence, penetrance, carrier frequency, founder effects, validated modifier genes, environmental or protective factors, gene–environment interactions, epigenetic signatures, human single-cell/spatial multi-omics, standardized quality-of-life data, natural animal disease and human treatment-response rates are not established in the gathered evidence. | No ontology assignment recommended until evidence is available. | (pqac-00000005, pqac-00000023, pqac-00000025) |


*Table: Compact evidence table covering disease identity, genetics, phenotype, mechanism, diagnostic approach, prognosis, treatment status, experimental models and major knowledge gaps. Ontology mappings are explicitly suggested rather than asserted.*