Retinitis Pigmentosa (RP)

name: Retinitis Pigmentosa
display_name: Retinitis Pigmentosa (RP)
creation_date: "2026-09-25T00:00:00Z"
description: >-
  Retinitis pigmentosa (RP) is the largest family of inherited retinal
  dystrophies: progressive rod-first photoreceptor degeneration presenting as
  night blindness, then constricting peripheral visual fields from
  non-cell-autonomous secondary cone degeneration, with bone-spicule
  pigmentation, attenuated retinal vessels, and a reduced or extinguished
  electroretinogram. More than 80 genes cause it across every Mendelian mode of
  inheritance (including digenic PRPH2/ROM1), and the causal genes span
  functionally unrelated classes - phototransduction components, outer-segment
  structural proteins, connecting-cilium and BBSome trafficking machinery,
  ubiquitous pre-mRNA splicing factors with photoreceptor-restricted
  phenotypes, RPE phagocytosis and visual-cycle enzymes, and metabolic
  housekeeping genes with retina-selective vulnerability. In dismech this
  family is deliberately curated as gene-specific Disease entries (matching
  MONDO's gene-based "-related retinopathy" classes) that share the conserved
  distal cascade through conformance to the photoreceptor_degeneration module
  while each carrying its own proximal mechanism; this grouping is the
  explicit union over those entries.
grouping_basis:
- SHARED_PHENOTYPE
- SHARED_MECHANISM
grouping_rationale: >-
  Grouped on a shared clinical phenotype (progressive rod-cone dystrophy, the
  RP presentation) and a shared final-common-pathway mechanism (rod
  photoreceptor apoptosis followed by secondary cone degeneration, the
  photoreceptor_degeneration module). The members are deliberately kept as
  separate gene-specific Disease entries rather than merged, because they
  differ in causal gene, proximal mechanism (rhodopsin misfolding, cGMP
  toxicity, ciliary cargo trafficking failure, spliceosome haploinsufficiency,
  RPE phagocytic failure, visual-cycle arrest, heme export failure), mode of
  inheritance, and - decisively for treatment - in therapeutic strategy, which
  is gene- and mechanism-specific (RPE65 gene therapy, RPGR gene therapy
  trials, splice-modulating and allele-specific approaches). The scope is
  entries in which RP is the defining, retina-led presentation: nonsyndromic
  gene-specific retinopathies, mechanism-anchored nonsyndromic classes
  (BBSome-related RP), retinopathy-defined entries with a variable extra-ocular
  arm (FLVCR1/PCARP, ARL2BP/RP66), and named RP subtypes of retina-restricted
  spectrum entries (RP7, RP12, RP19, BEST1-RP). Multisystem syndromic diseases in which
  RP is one arm of a broader syndrome (Usher syndrome, Bardet-Biedl syndrome,
  Alstrom syndrome, Senior-Loken syndrome, PHARC, Refsum disease, NARP,
  Kearns-Sayre syndrome) are deliberately excluded; they are covered by their
  own entries and by the Ciliopathies and BBSome-opathies groupings, whose
  cross-cuts this grouping intersects but does not contain.
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0019200
      label: retinitis pigmentosa
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
    mapping_justification: >-
      The grouping concept corresponds to the MONDO retinitis pigmentosa
      class. exactMatch records the intended conceptual alignment; MONDO RP
      descendants without a dismech entry are curation gaps rather than
      evidence that the grouping is only a close match.
    consistency:
    - reference: MONDO
      consistent: INCONSISTENT
      notes: >-
        Recorded honestly as structurally inconsistent rather than as a defect
        of any single member: most members bind MONDO's newer gene-based
        "-related retinopathy" classes (e.g. MONDO:0800400 RP1-related dominant
        retinopathy, MONDO:0100442 RP2-related retinopathy, MONDO:0700224
        PDE6A-related retinopathy), which MONDO deliberately places under
        retinal dystrophy - spanning RP and allied diagnoses - rather than
        under MONDO:0019200. Descent from MONDO:0019200 is instead carried by
        RP-numbered terms where they are curated: MONDO:0019200 itself
        (BEST1-RP subtype), RP25/MONDO:0011272 (EYS primary term),
        RP66/MONDO:0014186 (the ARL2BP entry's primary term, an is-a
        descendant), RP59/MONDO:0013468 (the DHDDS entry's primary term, a
        direct is-a child), and the subtype bindings RP3/MONDO:0010227 (RPGR),
        RP4/MONDO:0013395 (RHO), RP7/MONDO:0011974 (PRPH2),
        RP12/MONDO:0010818 (CRB1), RP19/MONDO:0011137 (Stargardt),
        RP51/MONDO:0013274 (TTC8), RP55/MONDO:0013312 (ARL6),
        RP74/MONDO:0014692 (BBS2), and PCARP/MONDO:0012177 (FLVCR1). Members whose entries bind no
        RP-numbered MONDO class at all (RP1, RP2, PDE6A, CNGB1, PRPF31, MERTK,
        CERKL, RPE65, RLBP1, CFAP418, RCBTB1) belong on phenotype and
        mechanism, not on ontology descent.
membership_criteria:
- description: >-
    A disorder belongs to the retinitis pigmentosa grouping if progressive
    rod-first (rod-cone) photoreceptor degeneration is a defining
    presentation: it conforms to the inherited photoreceptor degeneration
    module's rod-apoptosis cascade, OR carries the rod-cone dystrophy
    phenotype, OR reaches the same photoreceptor/RPE degeneration endpoint
    through the retinoid visual-cycle disruption module (the ABCA4 route to
    RP19). Necessary only: the criterion is deliberately not sufficient,
    because the same module and phenotype are shared by allied non-RP
    dystrophies (cone-rod and macular dystrophies, choroideremia, gyrate
    atrophy, enhanced S-cone syndrome) and by syndromic diseases whose RP arm
    does not define them; the curated member list draws that boundary.
  criteria_semantics: NECESSARY
  logic:
    operator: OR
    description: >-
      The joint arms are not decoration; three members are admitted only by
      an arm other than photoreceptor_degeneration conformance. BEST1
      Bestrophinopathies (BEST1-RP subtype) and Retinitis Pigmentosa With or
      Without Situs Inversus (ARL2BP) declare no module conformance and enter
      through their curated rod-cone dystrophy phenotype. Stargardt Disease
      (ABCA4-related RP, RP19) conforms to the retinoid visual-cycle
      disruption module rather than the photoreceptor degeneration module,
      because severe biallelic ABCA4 loss reaches panretinal rod-cone
      degeneration through bisretinoid toxicity to the RPE - the third arm
      names that route explicitly.
    operands:
    - criterion_predicate: CONFORMS_TO_MODULE
      module: photoreceptor_degeneration#Rod Photoreceptor Apoptosis
      description: >-
        Has a pathophysiology node conforming to the inherited photoreceptor
        degeneration module (rod-first apoptosis with secondary cone
        degeneration).
    - criterion_predicate: HAS_PHENOTYPE
      description: Rod-cone dystrophy as a curated phenotype.
      phenotype_term:
        preferred_term: Rod-cone dystrophy
        term:
          id: HP:0000510
          label: Rod-cone dystrophy
    - criterion_predicate: CONFORMS_TO_MODULE
      module: retinoid_visual_cycle_disruption#Progressive Photoreceptor and Retinal Pigment Epithelium Degeneration
      description: >-
        Reaches progressive photoreceptor and RPE degeneration through the
        retinoid visual-cycle disruption module (visual-cycle enzyme or
        transporter defect with chromophore insufficiency or toxic retinoid
        accumulation).
members:
- member: RHO-Related Retinopathy
  member_type: DISEASE
  display_name: RHO-related retinopathy (RP4, autosomal dominant RP)
  differentiating_mechanisms:
  - description: >-
      The most common cause of autosomal dominant RP. Class-dependent dual
      mechanism: misfolding rhodopsin variants (P23H class) cause ER stress
      and proteotoxic rod death, while other classes constitutively activate
      phototransduction in darkness - the one member whose proximal lesion is
      the visual pigment itself.
    gene:
      preferred_term: RHO
      term:
        id: hgnc:10012
        label: RHO
    module: phototransduction_cascade_dysfunction#Phototransduction Cascade Component Defect
- member: PDE6A-Related Retinopathy
  member_type: DISEASE
  display_name: PDE6A-related retinopathy (RP43, autosomal recessive RP)
  differentiating_mechanisms:
  - description: >-
      Loss of the PDE6 alpha subunit abolishes rod cGMP hydrolysis; cGMP
      accumulation holds CNG channels open, and the resulting calcium and
      metabolic overload kills rods - the classic phototransduction
      second-messenger toxicity route, distinct from RHO's proteotoxic and
      constitutive-activation classes.
    gene:
      preferred_term: PDE6A
      term:
        id: hgnc:8785
        label: PDE6A
    module: phototransduction_cascade_dysfunction#Loss of Outer-Segment cGMP and Calcium Set-Point Control
- member: CNGB1-Related Retinopathy
  member_type: DISEASE
  display_name: CNGB1-related retinopathy (RP45, autosomal recessive RP)
  differentiating_mechanisms:
  - description: >-
      Biallelic loss of the rod CNG channel beta subunit destabilizes CNGA1
      and aborts channel assembly, so the rod loses its cGMP-gated
      conductance and its calcium set point - the channel-side counterpart of
      PDE6A's enzyme-side lesion in the same phototransduction axis.
      Distinguished by a long dissociation between loss of rod function and
      loss of rod structure, which gives CNGB1 disease an unusually wide
      window for gene therapy.
    gene:
      preferred_term: CNGB1
      term:
        id: hgnc:2151
        label: CNGB1
    module: phototransduction_cascade_dysfunction#Phototransduction Cascade Component Defect
- member: RP1-Related Retinopathy
  member_type: DISEASE
  display_name: RP1-related retinopathy (RP1)
  differentiating_mechanisms:
  - description: >-
      RP1 is a photoreceptor axoneme protein organizing outer-segment disc
      stacking. Distinguished by its allele-architecture split: heterozygous
      truncations in the dominant-negative hotspot cause autosomal dominant
      RP, while biallelic loss causes recessive disease - a structural
      axonemal mechanism rather than trafficking or signaling.
    gene:
      preferred_term: RP1
      term:
        id: hgnc:10263
        label: RP1
- member: RPGR-Related Retinopathy
  member_type: DISEASE
  display_name: RPGR-related retinopathy (RP3, X-linked RP)
  differentiating_mechanisms:
  - description: >-
      The major cause of X-linked RP. RPGR gates protein cargo through the
      photoreceptor connecting cilium; variant position (RPGR-ORF15 vs
      constitutive exons) biases rod-first versus cone-first degeneration.
      Distinguished from RP2 by acting as the connecting-cilium cargo
      gatekeeper rather than upstream trafficking GTPase regulation.
    gene:
      preferred_term: RPGR
      term:
        id: hgnc:10295
        label: RPGR
    module: ciliopathy_dysfunction#Photoreceptor Connecting Cilium Degeneration
- member: RP2-Related Retinopathy
  member_type: DISEASE
  display_name: RP2-related retinopathy (X-linked RP)
  differentiating_mechanisms:
  - description: >-
      The second X-linked RP locus. RP2 is the GTPase-activating protein for
      ARL3; its loss deregulates ARL3-dependent release of lipidated
      phototransduction proteins at the connecting cilium, mistrafficking
      outer-segment components - a trafficking-regulator lesion upstream of
      RPGR's cargo gate.
    gene:
      preferred_term: RP2
      term:
        id: hgnc:10274
        label: RP2
    module: ciliopathy_dysfunction#Basal Body and Transition Zone Dysfunction
- member: Retinitis Pigmentosa With or Without Situs Inversus
  member_type: DISEASE
  display_name: ARL2BP-related RP with or without situs inversus (RP66)
  differentiating_mechanisms:
  - description: >-
      Biallelic loss of ARL2BP, the ARL2/ARL3 effector at the photoreceptor
      basal body and connecting cilium, disrupts ciliary doublet-microtubule
      assembly and outer-segment organization - the same small-GTPase
      trafficking axis RP2 regulates from the GAP side. Rod-cone degeneration
      is present in every reported patient, while the extra-ocular motile-cilia
      features (situs inversus, sperm flagellar defects) are variable - the
      same retinopathy-defined pattern by which FLVCR1/PCARP is admitted.
    gene:
      preferred_term: ARL2BP
      term:
        id: hgnc:17146
        label: ARL2BP
- member: EYS-Related Retinitis Pigmentosa
  member_type: DISEASE
  display_name: EYS-related retinitis pigmentosa (RP25)
  differentiating_mechanisms:
  - description: >-
      Biallelic loss of EYS, a large eye-specific extracellular protein of the
      periciliary membrane that maintains outer-segment architecture. Because
      EYS expression is retina-restricted, the ciliopathy is purely ocular -
      one of the most common autosomal recessive RP genes in European and
      East Asian cohorts.
    gene:
      preferred_term: EYS
      term:
        id: hgnc:21555
        label: EYS
    module: ciliopathy_dysfunction#Basal Body and Transition Zone Dysfunction
- member: CFAP418-related retinal ciliopathy
  member_type: DISEASE
  display_name: CFAP418 (C8orf37) retinal ciliopathy (RP64)
  differentiating_mechanisms:
  - description: >-
      Biallelic CFAP418 variants disrupt a protein at the base of the
      connecting cilium, producing a photoreceptor-dominant allelic continuum
      from nonsyndromic RP with early macular involvement (RP64) and cone-rod
      dystrophy (CORD16) to Bardet-Biedl syndrome 21 at the syndromic extreme;
      it belongs here for its retina-led RP64 identity.
    gene:
      preferred_term: CFAP418
      term:
        id: hgnc:27232
        label: CFAP418
    module: ciliopathy_dysfunction#Photoreceptor Connecting Cilium Degeneration
- member: BBSome-related retinitis pigmentosa
  member_type: DISEASE
  display_name: BBSome-related nonsyndromic RP (RP51, RP55, RP74)
  differentiating_mechanisms:
  - description: >-
      The photoreceptor-restricted floor of the BBSome spectrum: hypomorphic
      or tissue-restricted BBSome-machine alleles (the BBS8 retina-specific
      exon, the BBS3L isoform, mild BBS1 p.M390R genotypes) cause partial
      ciliary cargo-trafficking loss expressed only in the photoreceptor,
      producing nonsyndromic RP without the obesity, polydactyly, renal, and
      cognitive arms of Bardet-Biedl syndrome.
    module: bbsome_trafficking#BBSome-Dependent Ciliary Cargo Trafficking Failure
- member: PRPF31-Related Retinopathy
  member_type: DISEASE
  display_name: PRPF31-related retinopathy (RP11)
  differentiating_mechanisms:
  - description: >-
      Haploinsufficiency of the ubiquitous tri-snRNP spliceosome assembly
      factor PRPF31 impairs splicing of highly spliceosome-demanding
      photoreceptor transcripts, degenerating only the retina; CNOT3-mediated
      modulation of wild-type allele expression makes RP11 the paradigm of
      incomplete penetrance in dominant RP. The one member whose proximal
      lesion is gene expression machinery rather than a photoreceptor or RPE
      protein.
    gene:
      preferred_term: PRPF31
      term:
        id: hgnc:15446
        label: PRPF31
- member: MERTK-Related Retinopathy
  member_type: DISEASE
  display_name: MERTK-related retinopathy (RP38)
  differentiating_mechanisms:
  - description: >-
      The lesion is in the retinal pigment epithelium, not the photoreceptor:
      loss of the MERTK receptor tyrosine kinase abolishes RPE phagocytosis of
      shed outer-segment discs, and accumulating debris kills rods
      secondarily - the human orthologue of the RCS rat mechanism, and the
      grouping's paradigm of non-cell-autonomous RP.
    gene:
      preferred_term: MERTK
      term:
        id: hgnc:7027
        label: MERTK
- member: RPE65-Related Retinopathy
  member_type: DISEASE
  display_name: RPE65-related retinopathy (LCA2/EOSRD-RP continuum)
  differentiating_mechanisms:
  - description: >-
      Loss of the RPE isomerohydrolase arrests the visual cycle: 11-cis-retinal
      chromophore starvation silences rods first and photoreceptors degenerate
      progressively, on a severity continuum from Leber congenital amaurosis
      to early-onset severe retinal dystrophy/RP20. The first inherited
      retinal disease with an approved gene therapy (voretigene neparvovec).
    gene:
      preferred_term: RPE65
      term:
        id: hgnc:10294
        label: RPE65
    module: retinoid_visual_cycle_disruption#Visual Cycle Enzyme or Transporter Defect
- member: RLBP1-Related Retinopathy
  member_type: DISEASE
  display_name: RLBP1-related retinopathy (retinitis punctata albescens)
  differentiating_mechanisms:
  - description: >-
      Loss of CRALBP slows 11-cis-retinol oxidation in the RPE and Muller
      glia, producing profoundly delayed dark adaptation with white punctate
      fundus flecks (retinitis punctata albescens) that progresses to
      rod-cone degeneration - a visual-cycle kinetics lesion distinguished
      from RPE65's outright chromophore synthesis arrest.
    gene:
      preferred_term: RLBP1
      term:
        id: hgnc:10024
        label: RLBP1
- member: CERKL-Related Retinopathy
  member_type: DISEASE
  display_name: CERKL-related retinopathy (RP26)
  differentiating_mechanisms:
  - description: >-
      Biallelic CERKL loss removes a photoreceptor stress-resilience factor:
      impaired protection against oxidative stress with mitochondrial
      fragmentation and dysregulated autophagy drives degeneration that is
      often cone-involving from early on - a metabolic-resilience lesion
      rather than a structural, trafficking, or signaling defect.
    gene:
      preferred_term: CERKL
      term:
        id: hgnc:21699
        label: CERKL
- member: FLVCR1-Related Retinopathy with or without Ataxia
  member_type: DISEASE
  display_name: FLVCR1-related retinopathy / PCARP
  differentiating_mechanisms:
  - description: >-
      Loss of the FLVCR1 heme exporter causes intracellular heme accumulation
      and oxidative toxicity; the FLVCR1 expression gradient makes
      photoreceptors and posterior-column sensory neurons the vulnerable
      tissues, so the spectrum runs from nonsyndromic RP to posterior column
      ataxia with retinitis pigmentosa (PCARP). Included because the
      retinopathy defines the entry; the ataxia arm is variable.
    gene:
      preferred_term: FLVCR1
      term:
        id: hgnc:24682
        label: FLVCR1
- member: RCBTB1-Related Retinopathy
  member_type: DISEASE
  display_name: RCBTB1-related retinopathy
  differentiating_mechanisms:
  - description: >-
      Biallelic RCBTB1 variants impair a CUL3 E3-ubiquitin-ligase adaptor
      regulating the NRF2 antioxidant response in the retina, producing
      rod-cone and chorioretinal degeneration with a distinctive reticular
      pattern - an oxidative-stress-defence lesion adjacent to CERKL's but
      acting through ubiquitin-dependent NRF2 regulation.
    gene:
      preferred_term: RCBTB1
      term:
        id: hgnc:18243
        label: RCBTB1
- member: Retinitis Pigmentosa 59
  member_type: DISEASE
  display_name: DHDDS-related retinitis pigmentosa (RP59)
  differentiating_mechanisms:
  - description: >-
      Biallelic hypomorphic DHDDS alleles (almost always the Ashkenazi Jewish
      founder K42E) partially disable the catalytic subunit of the
      cis-prenyltransferase that builds the dolichol backbone, shortening the
      dolichol pool (dolichol-18 replacing dolichol-19 in plasma and urine) -
      the grouping's lipid-carrier biosynthesis lesion. Although dolichol is
      the carrier for protein N-glycosylation, transferrin glycosylation is
      usually normal and knock-in and rod-specific knockout mice degenerate
      without detectable retinal hypoglycosylation, so how the dolichol
      deficit kills photoreceptors is unresolved.
    gene:
      preferred_term: DHDDS
      term:
        id: hgnc:20603
        label: DHDDS
    module: photoreceptor_degeneration#Photoreceptor Gene Defect
- member: PRPH2-Related Retinopathy
  member_type: SUBTYPE
  display_name: Retinitis pigmentosa 7 (PRPH2, including digenic PRPH2/ROM1)
  differentiating_mechanisms:
  - description: >-
      The RP7 and digenic RP7 subtypes of the PRPH2 spectrum: peripherin-2
      tetramerization with ROM1 builds and curves the outer-segment disc rim,
      and assembly-defective alleles cause dominant RP - including the classic
      digenic inheritance in double heterozygotes for PRPH2 L185P and a ROM1
      null. The wider PRPH2 entry also spans pattern and vitelliform macular
      dystrophies, which are not RP and are not covered by this membership.
    gene:
      preferred_term: PRPH2
      term:
        id: hgnc:9942
        label: PRPH2
  - description: >-
      ROM1 contributes the second locus of the digenic RP7 genotype; a ROM1
      null allele is disease-causing only together with an assembly-impaired
      PRPH2 allele.
    gene:
      preferred_term: ROM1
      term:
        id: hgnc:10254
        label: ROM1
- member: CRB1 Retinal Dystrophies
  member_type: SUBTYPE
  display_name: Retinitis pigmentosa 12 (CRB1)
  differentiating_mechanisms:
  - description: >-
      The RP12 subtype of the CRB1 spectrum: loss of CRB1 at the outer
      limiting membrane breaks the Muller glia-photoreceptor scaffold,
      producing early-onset RP with preserved para-arteriolar RPE and a
      thickened, coarsely laminated retina - an apical-polarity scaffold
      lesion unique in the grouping. The parent entry also spans LCA8 and
      macular dystrophy, not covered by this membership.
    gene:
      preferred_term: CRB1
      term:
        id: hgnc:2343
        label: CRB1
- member: Stargardt Disease
  member_type: SUBTYPE
  display_name: ABCA4-related retinitis pigmentosa (RP19)
  differentiating_mechanisms:
  - description: >-
      The RP19 pole of the ABCA4 spectrum: with two severe/null ABCA4 alleles,
      failure to clear retinaldehyde-phosphatidylethanolamine adducts from
      outer segments loads the RPE with toxic bisretinoids panretinally, and
      degeneration presents as rod-cone dystrophy rather than the central
      maculopathy of classic Stargardt disease. Enters the membership
      criterion through the retinoid visual-cycle disruption arm.
    gene:
      preferred_term: ABCA4
      term:
        id: hgnc:34
        label: ABCA4
    module: retinoid_visual_cycle_disruption#RPE Lipofuscin Loading and Retinal Pigment Epithelium Dysfunction
- member: BEST1 Bestrophinopathies
  member_type: SUBTYPE
  display_name: BEST1-associated retinitis pigmentosa (BEST1-RP)
  differentiating_mechanisms:
  - description: >-
      The BEST1-RP subtype of the bestrophinopathy spectrum: specific
      autosomal dominant BEST1 alleles impair the RPE calcium-activated
      chloride channel in a pattern that produces panretinal rod-cone
      degeneration instead of the vitelliform maculopathy of Best disease -
      the grouping's only channelopathy, and its lesion sits in RPE ionic
      homeostasis rather than in the photoreceptor.
    gene:
      preferred_term: BEST1
      term:
        id: hgnc:12703
        label: BEST1
notes: >-
  Scope and coverage decisions:

  (1) Syndromic RP is deliberately out of scope. Usher syndrome (the most
  common syndromic RP), Bardet-Biedl syndrome, Alstrom syndrome, Senior-Loken
  syndrome, PHARC, adult Refsum disease, NARP, and Kearns-Sayre syndrome all
  manifest RP or pigmentary retinopathy as one arm of a multisystem syndrome;
  their identities are the syndromes, and several are already organized by the
  Ciliopathies grouping. This grouping intersects those cross-cuts (EYS,
  RPGR, RP2, CFAP418, and BBSome-related RP are also ciliopathies) without
  containing them, which is why BBSome-opathies is not nested here: its other
  members (Bardet-Biedl syndrome, McKusick-Kaufman syndrome) are not RP.

  (2) IFT140-related recessive ciliopathy carries nonsyndromic RP80 as a named
  subtype but is not listed: the parent entry is a multisystem skeletal-renal
  ciliopathy, GroupingMember has no subtype-reference slot (member_type:
  SUBTYPE still names the parent Disease), and the parent-level facts (coarse
  HP:0000556 retinal dystrophy annotation, ciliopathy_dysfunction conformance
  only) would sit as a standing contradiction under the NECESSARY criterion.
  Same limitation as IL17_Immunity_Defects note (1); if a subtype-granular
  membership slot is added, RP80 belongs here.

  (3) The Inherited Retinal Dystrophy entry (MONDO:0019118) is a broader
  umbrella mechanism entry whose own subtypes include RP; it is not a distinct
  disease and is not a member. This grouping takes over the explicit-union
  role for the RP slice of that umbrella.

  (4) Known member entries not listed on purpose: Choroideremia, Bietti
  crystalline dystrophy, ornithine aminotransferase deficiency (gyrate
  atrophy), Enhanced S-Cone Syndrome, and the cone-led GUCY2D/CRX/AIPL1/LCA5
  retinopathies all conform to the photoreceptor_degeneration module but are
  distinct clinical diagnoses, not RP - which is also why the membership
  criterion is NECESSARY rather than SUFFICIENT. Taurine transporter
  deficiency (SLC6A6; MONDO:0007777 hypotaurinemic retinal degeneration and
  cardiomyopathy) also conforms to the module and curates rod-cone dystrophy,
  but is excluded as syndromic under note (1): cardiomyopathy is a defining
  arm of the disease, named in its MONDO label.

  (5) MONDO RP-numbered descendants without a dismech entry (surfaced by the
  exactMatch mapping, e.g. the many RP loci with no gene-specific entry yet)
  are curation gaps, not omissions from a complete list.