Hearing Loss, Autosomal Recessive 108 (DFNB108) — Comprehensive Research Report

1. Disease Information

Overview. Autosomal recessive deafness-108 (DFNB108) is an ultra-rare, nonsyndromic form of hereditary hearing loss caused by biallelic mutation of ROR1 (Receptor tyrosine kinase-like Orphan Receptor 1) on chromosome 1p31.3. It was first delineated in 2016 in a single consanguineous Turkish kindred, in which two affected siblings had congenital, profound sensorineural hearing loss accompanied by a distinctive inner-ear malformation (fusion of the cochlea and vestibule into a common cavity) and electrophysiologic features of auditory neuropathy (Tang et al., PNAS 2016, PMID:27162350). To date this remains, per the literature identified in this search, the founding and principal report defining the locus; the entry is otherwise sparsely represented in subsequent case series, consistent with its designation as an ultra-rare DFNB subtype.

Key identifiers: - OMIM: #617654 — DEAFNESS, AUTOSOMAL RECESSIVE 108; DFNB108 (phenotype); causative gene ROR1, OMIM 602336 (chromosome 1p31.3) - MONDO: MONDO:0033200 - GARD (NORD/NCATS) ID: 22658 - Gene: ROR1 — HGNC:10256; NCBI Gene ID 4919; RefSeq transcript NM_005012.4; genomic span chr1:63,774,017–64,181,498 (GRCh38), band 1p31.3 - Inheritance:* Autosomal recessive - No distinct ICD-10/ICD-11 code exists beyond the generic hereditary sensorineural hearing loss codes (ICD-10 H90.3/H90.5); no MeSH heading specific to DFNB108 was found — it is subsumed under "Deafness" (MeSH D003638) and "Hearing Loss, Sensorineural" more broadly.

Synonyms: Autosomal recessive nonsyndromic deafness 108; Deafness, autosomal recessive 108; DFNB108.

Provenance of current knowledge: This is a single-family, aggregated clinical-genetic disease-level description (OMIM/MONDO curation of one primary report), not an EHR-derived or population-registry-derived entity. All clinical detail traces to one kindred; no independent replication family was identified in this search.

Sources: - 617654 - DEAFNESS, AUTOSOMAL RECESSIVE 108 - OMIM - hearing-loss-autosomal-recessive-108 - NORD/MONDO - ROR1 is essential for proper innervation of auditory hair cells and hearing in humans and mice - PubMed

2. Etiology

Disease causal factor: Purely monogenic/genetic — homozygous missense mutation in ROR1. No environmental, infectious, or acquired contributing factor has been reported; this is a pure Mendelian etiology, not a multifactorial or gene-environment interaction disease.

Genetic risk factor (the causal variant): NM_005012.4(ROR1):c.2207G>C, p.(Arg736Thr) ("R736T"), identified by whole-exome sequencing and confirmed by Sanger sequencing in two affected siblings of a consanguineous Turkish family; it segregated with hearing loss in the pedigree (autozygosity consistent with consanguinity). ClinVar Variation ID 437889 (Accession VCV000437889.1); genomic position chr1:64,178,248 (GRCh38).

Population frequency: The variant was absent from ExAC, the Exome Variant Server (EVS), and 1000 Genomes Project, and was not found in 330 ethnicity-matched Turkish control chromosomes — consistent with a private, family-specific ultra-rare allele rather than a founder variant with broader carrier frequency. No gnomAD frequency data beyond "absent/not observed" were retrievable in this search.

Modifier genes: None reported — no modifier locus or second hit has been described for DFNB108.

Protective factors: None identified in the literature (genetic or environmental) — as an ultra-rare monogenic disorder, no protective-allele or lifestyle-protective-factor studies exist.

Gene-environment interactions: Not applicable/not reported; there is no evidence of environmental modulation of ROR1-related hearing loss.

Consanguinity: Directly implicated — the index family were consanguineous Turkish parents, and homozygosity for a rare private variant is the expected mechanism in such pedigrees (autozygosity mapping context implied by exome sequencing approach in a consanguineous family).

Sources: - NM_005012.4(ROR1):c.2207G>C (p.Arg736Thr) AND Hearing loss, autosomal recessive 108 - ClinVar - VCV000437889.1 - ClinVar - 617654 - OMIM

3. Phenotypes

All phenotype data derive from the two affected siblings in the single reported kindred (OMIM Clinical Synopsis #617654; Tang et al. 2016).

Quality-of-life impact: Not formally measured with QOL instruments in the primary report; profound prelingual, congenital deafness carries the generic QOL burden of hereditary nonsyndromic hearing loss (impact on spoken-language acquisition, communication, and, per general common-cavity literature, cochlear-implant candidacy/outcomes are typically poorer than in structurally normal ears — see Treatment section).

Note on evidentiary basis: All phenotype frequencies above are "2 of 2" because the entire phenotype description rests on a single sibling pair; this is not a population-level frequency estimate and should be flagged as such in any curated entry (small-n, single-family denominator).

Source: Clinical Synopsis - #617654 - OMIM (content inferred from cached search-engine excerpts of the OMIM synopsis and the PNAS primary report; OMIM's own pages returned HTTP 403 to direct fetch in this session — treat exact OMIM synopsis wording as unverified pending direct access)

4. Genetic/Molecular Information

Causal gene: ROR1 (Receptor Tyrosine Kinase-Like Orphan Receptor 1), OMIM *602336, HGNC:10256, NCBI Gene 4919, chr1p31.3.

Pathogenic variant: - cDNA change: c.2207G>C (NM_005012.4) - Protein change: p.Arg736Thr (R736T) - Zygosity/origin: Homozygous, germline (both affected siblings; consanguineous parents presumed obligate heterozygous carriers) - Variant type/class: Missense - Domain affected: Falls within/near the intracellular tyrosine-kinase domain of ROR1 (ROR1 is classified as a pseudokinase — see Mechanism). Molecular modeling in the primary report indicated the mutated residue maps to the kinase catalytic domain region and predicted a conformational change potentially impairing substrate/ligand-response interactions. - ACMG/ClinVar classification: Listed in ClinVar (Variation ID 437889 / RCV000504579.2) associated with "Hearing loss, autosomal recessive 108" — classification category not independently confirmed in this search (recommend verifying current ClinVar star-rating/classification directly before citing as "Pathogenic"). - Population frequency: Absent from ExAC, EVS, 1000 Genomes, and 330 Turkish control chromosomes — i.e., not present in any queried reference population database, consistent with an ultra-rare/private allele. - Functional consequence: Loss-of-function-type mechanism at the cell-biology level — in heterologous transfection (MDCK II cells), wild-type ROR1 trafficked normally to the plasma membrane, whereas the R736T mutant showed markedly reduced membrane localization. Functionally, in the presence of the ROR1 ligand WNT5A, mutant ROR1 failed to activate NF-κB signaling (wild-type ROR1 does activate NF-κB upon WNT5A stimulation). This supports a loss-of-function mechanism (FunctionalImpactEnum: LOSS_OF_FUNCTION, or PARTIAL_LOSS_OF_FUNCTION given some low residual membrane expression was noted).

Modifier genes: None reported.

Epigenetic information: No DNA methylation, histone-modification, or chromatin studies of ROR1 in the context of hearing loss were identified.

Chromosomal abnormalities: Not applicable — this is a single-gene missense disorder, not a copy-number or structural chromosomal disease.

Somatic vs. germline: Germline only in the context of DFNB108. (Note: ROR1 is separately and extensively studied as a somatically overexpressed oncofetal antigen in chronic lymphocytic leukemia and multiple solid tumors — this is an entirely distinct disease context and must not be conflated with the germline deafness mechanism; per dismech design decision to keep germline and somatic mechanisms separate.)

Suggested ontology terms: - Gene: hgnc:10256 (ROR1) - GO Molecular Function candidates: GO:0004714 (transmembrane receptor protein tyrosine kinase activity) — noting ROR1 is a pseudokinase with debated catalytic activity; GO:0005112 (Notch binding) not relevant; more precisely GO:0038131 (neuregulin receptor activity) is not correct either — recommend verifying the most specific current GO MF annotation for ROR1 (Wnt receptor activity, GO:0042813, is a strong candidate given its Frizzled-like CRD domain) via OAK/AmiGO before binding. - GO Biological Process: GO:0060042 (retina morphogenesis in camera-type eye) not relevant; better candidates: GO:0007605 (sensory perception of sound) is too generic; GO:0021675 (nerve development) and axon guidance/fasciculation terms (GO:0007409 axonogenesis; GO:0033563 dorsal/ventral axon guidance) are more mechanistically apt given the mouse phenotype (see Mechanism section) — verify each against OAK before binding.

Sources: - 617654 & 602336 - OMIM - VCV000437889.1 - ClinVar - ROR1 Gene - GeneCards

5. Environmental Information

No environmental factors, lifestyle factors, or infectious agents have been reported to cause or modify DFNB108 — it is a purely monogenic disorder with no described gene-environment interaction, ototoxic exposure link, or infectious trigger. This section is not applicable for this entry beyond noting the general principle (shared with most nonsyndromic hereditary hearing loss) that maternal ototoxic drug exposure, perinatal infection (e.g., CMV), and noise exposure are differential-diagnostic considerations for congenital SNHL generally, but none is implicated specifically in the ROR1-associated cases reported.

6. Mechanism / Pathophysiology

Ordered causal chain (as currently supported by the primary human-genetic and mouse-model evidence; several steps are inferred from the mouse model rather than directly demonstrated in human tissue — flagged below)

1. Homozygous ROR1 c.2207G>C (p.R736T) missense mutation leads to a conformational change in the ROR1 protein's kinase-domain region (demonstrated: molecular modeling, PMID:27162350).
2. This conformational change results in impaired trafficking of ROR1 to the plasma membrane, demonstrated directly in transfected MDCK II cells (mutant protein shows markedly reduced membrane localization vs. wild-type) (demonstrated: in vitro/heterologous cell system — evidence_source: IN_VITRO).
3. Reduced membrane-localized ROR1 results in failure to transduce the WNT5A (non-canonical Wnt) signal upon ligand binding — specifically, mutant ROR1 fails to activate NF-κB signaling in response to WNT5A, whereas wild-type ROR1 does (demonstrated: in vitro functional assay).
4. Loss of WNT5A→ROR1→NF-κB (and, by extension, non-canonical Wnt/planar-cell-polarity–type) signaling in the developing inner ear leads to (inferred primarily from the Ror1-mutant mouse model, not directly shown in human tissue — evidence_source: MODEL_ORGANISM, directness: INDIRECT relative to the human disease):
5. Branch A — Cochlear morphogenesis defect: impaired convergent-extension-type morphogenesis results in an under-coiled, shortened cochlea, phenocopying the disrupted-Wnt-PCP cochlear elongation phenotype seen with loss of other Wnt5a-pathway components (Wnt5a-knockout mice independently show a shortened cochlea and rotated stereociliary bundles, supporting a shared pathway). In the human patients this branch is presumed to correspond to the common cavity inner-ear malformation seen on HRCT (fusion of cochlea and vestibule) — this specific structural correspondence between the mouse cochlear-coiling defect and the human common-cavity anomaly is an inference, not a demonstrated one-to-one mapping.
6. Branch B — Spiral ganglion neuron (SGN) innervation defect: loss of ROR1 function in spiral ganglion neuron growth cones leads to axon fasciculation defects, which result in (i) impaired/absent synapse formation between type I SGN afferents and inner hair cells (with postsynaptic glutamate receptor clusters not detectable at some contacts), and (ii) aberrant, mistargeted projections of type II SGN afferents through the sensory epithelium (normally type II afferents innervate outer hair cells). This SGN innervation failure is proposed to explain the human auditory-neuropathy electrophysiologic pattern (preserved cochlear amplifier function → present otoacoustic emissions, but absent/abnormal neural transmission → profound hearing loss on auditory brainstem response) — again, this human-mouse correspondence is inferred by analogy rather than directly tested in human inner-ear tissue (which is inaccessible for biopsy).
7. The combined structural (cochlear shortening) and neural (afferent innervation failure) deficits culminate in profound congenital sensorineural hearing loss with an auditory-neuropathy electrophysiologic signature, while sparing vestibular function — consistent with the mouse model showing normal vestibular anatomy, no circling/balance abnormality, and normal rotarod performance despite the cochlear and SGN phenotypes, and consistent with the human patients' normal balance/neuromotor development.

Category detail

• Molecular pathways: Non-canonical WNT signaling (WNT5A–ROR1 axis) → NF-κB activation; ROR1 also participates more broadly in planar cell polarity (PCP)–type signaling relevant to cochlear duct elongation (a mechanism it likely shares with other PCP genes implicated in cochlear coiling defects, though this was not itself directly tested in the primary report beyond the parallel drawn to Wnt5a-null mice).
• Cellular processes: Axon guidance/fasciculation of spiral ganglion neurons; convergent-extension-type morphogenetic movements during cochlear duct elongation; synaptogenesis (afferent neuron–hair cell synapse formation).
• Protein dysfunction: ROR1 is normally a type I transmembrane glycoprotein with an extracellular immunoglobulin-like domain, a Frizzled-homologous cysteine-rich domain (CRD, the WNT5A-binding module), and a kringle domain, plus an intracellular tyrosine-kinase-like (pseudokinase) domain. The R736T mutation causes defective membrane trafficking (protein retained intracellularly rather than reaching the plasma membrane) — a loss-of-function mechanism at the level of protein localization, compounding any intrinsic catalytic/signaling defect.
• Biochemical abnormality: Failure of ligand (WNT5A)-induced NF-κB pathway activation — an intracellular signal-transduction defect downstream of a receptor-trafficking defect.
• Tissue damage mechanism: Not classical damage (necrosis/fibrosis) but a developmental patterning/innervation failure — i.e., this is a malformation/miswiring disorder rather than a degenerative one; no evidence of postnatal progressive hair-cell death was reported.
• Immune system involvement: None directly relevant to the deafness mechanism, despite NF-κB (canonically an immune/inflammatory pathway) being the downstream readout used experimentally — its role here is developmental/neuronal, not immunological.
• Epigenetic changes: None reported.
• Molecular/omics profiling: No transcriptomic, proteomic, or single-cell profiling of ROR1-mutant human or mouse inner ear was identified in this search beyond the targeted immunohistochemistry/electrophysiology used in the primary paper (SGN axon tracing, synaptic marker staining, ABR/DPOAE electrophysiology, HRCT imaging).

Suggested GO/CL terms for pathophysiology nodes (verify each via OAK before binding, per dismech term-validation policy): - GO:0007409 axonogenesis / GO:0042060 wound healing (not relevant) — better: axon fasciculation-specific GO terms should be searched directly (e.g., GO:0007413 axonal fasciculation) - GO:0060429 epithelium development / cochlear duct morphogenesis-specific terms (search GO for "cochlear duct morphogenesis") - Cell types: CL:0000101 (sensory neuron) is too generic — spiral ganglion neuron type I and type II afferent subtypes should be searched in CL specifically (e.g., "type I spiral ganglion neuron," "type II spiral ganglion neuron") if present; inner hair cell (CL:0002131) and outer hair cell (CL:0002062) as the postsynaptic/target cell types.

Note on evidence-source discipline: Per dismech curation rules, the human-derived findings (variant identification, segregation, HRCT imaging, audiometry/ABR/OAE) are HUMAN_CLINICAL; the transfection/membrane-trafficking and NF-κB signaling assays are IN_VITRO; the Ror1-knockout mouse cochlear, SGN, and behavioral phenotyping is MODEL_ORGANISM. The mouse-to-human mechanistic bridge (steps 4–5 above) should be flagged in any dismech entry as model-organism-derived mechanistic inference, not directly demonstrated human pathophysiology — a candidate for a HUMAN_MODEL_MISMATCH-type discussion node given that human inner-ear tissue was never directly examined.

Source: ROR1 is essential for proper innervation of auditory hair cells and hearing in humans and mice - PNAS/PubMed, PMID:27162350

7. Anatomical Structures Affected

Organ level: - Primary organ: Inner ear (cochlea and vestibule) — bilateral involvement implied (both siblings affected, bilateral profound SNHL). - Secondary/systemic involvement: None — this is a nonsyndromic disorder; no other organ system is affected. Speech/language delay is a downstream developmental consequence of deafness, not a direct disease manifestation of another organ. - Body system: Auditory/nervous system (cochleovestibular apparatus and its afferent innervation by the VIIIth cranial nerve/spiral ganglion).

Tissue/cell level: - Cochlear duct epithelium; organ of Corti (inner and outer hair cells); spiral ganglion (bipolar sensory neurons, type I afferents to inner hair cells, type II afferents to outer hair cells). - Suggested Cell Ontology terms: CL:0002131 (auditory hair cell / inner hair cell — verify exact CL ID), CL:0002062 (outer hair cell — verify), spiral ganglion neuron subtypes (search CL directly for type I/II).

Subcellular level: - Plasma membrane (site of normal ROR1 localization; defective in the R736T mutant) — GO Cellular Component: GO:0005886 (plasma membrane). - Axon growth cone (site of ROR1-mediated axon guidance) — GO:0030426 (growth cone).

Localization: - Bilateral (both ears affected in both siblings; no laterality asymmetry reported). - Suggested UBERON terms: UBERON:0000955 is brain (not this); relevant terms — UBERON:0001846 (cochlea), UBERON:0001846-adjacent vestibule terms, UBERON:0002105 (inner ear) — verify exact IDs via OAK before binding; "common cavity" as a malformed fused cochleovestibular structure may not have a precise single UBERON term and could require a qualifier/descriptor approach.

8. Temporal Development

• Onset: Congenital — hearing loss is present from birth/infancy in both reported cases; no reported cases of later-onset or progressive worsening.
• Onset pattern: Not acute/insidious in the acquired-disease sense — it is a static congenital malformation/miswiring defect present from birth.
• Progression: No progression documented; the report does not describe worsening over the observation period (available follow-up duration in the two siblings was not detailed further in retrievable sources — recommend flagging as "stability status incompletely documented beyond initial diagnosis" if precise longitudinal follow-up data cannot be confirmed from the primary paper).
• Disease course pattern: Stable/non-progressive as best described (congenital and static, characteristic of a structural/developmental innervation defect rather than a degenerative process).
• Disease duration: Lifelong (congenital sensorineural hearing loss is permanent).
• Critical period: The critical developmental window is prenatal cochlear/SGN morphogenesis (ROR1-dependent inner-ear patterning and afferent innervation occurs during embryonic and early postnatal inner-ear development in the mouse model) — i.e., pathogenesis is complete before or shortly after birth, meaning there is no known postnatal therapeutic window to prevent the structural/innervation defect (in contrast to some progressive hearing-loss genes where early intervention could theoretically slow decline).

9. Inheritance and Population

• Epidemiology: No prevalence or incidence estimate exists — DFNB108 has been described in a single consanguineous family (2 affected siblings), making it one of the rarest of the >100 known DFNB loci. It cannot be assigned even an Orphanet numeric prevalence band; classify (per dismech PrevalenceClassEnum) as effectively CASES_IN_LITERATURE / ultra-rare, with only 2 reported cases worldwide in the literature identified by this search.
• Inheritance pattern: Autosomal recessive (DFNB nomenclature confirms this — "DFNB" prefix denotes autosomal recessive nonsyndromic deafness loci, as opposed to DFNA [dominant] or DFNX [X-linked]).
• Penetrance: Presumed complete in the homozygous state (both homozygous siblings affected); no data on incomplete penetrance.
• Expressivity: Consistent between the two reported siblings (both had profound congenital SNHL with the same common-cavity malformation) — apparently uniform expressivity, though n=2 limits generalization.
• Genetic anticipation: Not applicable (missense variant, not a repeat-expansion disorder).
• Germline mosaicism: Not reported/assessed.
• Founder effect: Not established — the variant was not found in 330 Turkish population controls, arguing against a Turkish founder allele; more consistent with a private familial variant arising independently in this consanguineous pedigree.
• Consanguinity: Central to this family's presentation — parents were consanguineous, consistent with autozygosity for a rare recessive allele, the classic mechanism by which private recessive-deafness alleles are discovered in relatively small, well-documented pedigrees.
• Carrier frequency: Unknown/not estimated in any population database (absent from ExAC, EVS, 1000 Genomes).
• Affected population/geographic distribution: Reported only in a Turkish family; no other ethnic group or geographic region has been reported to carry this variant or locus to date, per this search.
• Sex ratio: No sex bias expected or reported (autosomal recessive; both reported affected siblings' sexes were not specified in the retrievable abstracts).
• Age distribution: Congenital onset only — no adult-onset cases described.

10. Diagnostics

Clinical/audiologic tests: - Standard newborn hearing screening (otoacoustic emissions [OAE] + automated auditory brainstem response [AABR]) would be expected to show a characteristic "pass" on OAE but "refer/abnormal" on ABR pattern — the auditory-neuropathy signature reported in this family (present DPOAEs with absent/abnormal ABR) is diagnostically important because it distinguishes cochlear (hair-cell) causes of deafness from neural/synaptic causes, and should prompt genetic and imaging work-up rather than being dismissed as a screening artifact. - Pure-tone/behavioral audiometry once developmentally feasible: profound bilateral SNHL. - Suggested LOINC: standard audiometry and ABR/OAE LOINC codes apply generically; no disease-specific biomarker or laboratory test exists.

Imaging: - High-resolution CT (HRCT) of the temporal bones is the key imaging diagnostic — identifies the common cavity deformity (fusion of cochlea and vestibule into one chamber), a major/hallmark structural finding in this family. MRI of the internal auditory canals could complementarily assess the cochlear nerve.

Genetic testing: - Given the auditory-neuropathy-plus-inner-ear-malformation phenotype and lack of a distinctive syndromic pattern, whole-exome sequencing (as used in the discovery family) or a comprehensive hereditary hearing-loss gene panel (which would need to specifically include ROR1, since it is not part of most legacy/older deafness panels given its very recent disease association) is the appropriate testing strategy. Single-gene ROR1 Sanger sequencing is reasonable for segregation confirmation once a proband variant is found, and in populations/families with known consanguinity, homozygosity mapping/autozygosity analysis alongside exome sequencing is efficient (as was done in the discovery family). - Chromosomal microarray/karyotype/FISH: Not applicable — DFNB108 is not caused by a copy-number or chromosomal rearrangement. - Mitochondrial DNA testing: Not applicable (nuclear gene disorder).

Differential diagnosis: Other DFNB loci associated with inner-ear malformations and/or auditory neuropathy should be considered, including OTOF-related auditory neuropathy (DFNB9, normal inner-ear anatomy typically), PJVK/DFNB59, and other cochleovestibular malformation syndromes (e.g., Pendred syndrome/SLC26A4 for enlarged vestibular aqueduct — distinguishable by imaging pattern and syndromic features such as goiter). Common cavity deformity itself has a broad differential including CHARGE syndrome and other inner-ear dysplasias, which should be excluded by absence of syndromic features.

Screening: Standard universal newborn hearing screening would detect the profound hearing loss; there is no ROR1-specific population carrier-screening program given the ultra-rarity of the variant/locus.

11. Outcome/Prognosis

• Survival/mortality: No excess mortality — DFNB108 is a nonsyndromic hearing-only disorder with no reported systemic or life-limiting complications; normal life expectancy is expected.
• Morbidity/function: The principal morbidity is profound, permanent, prelingual sensorineural hearing loss with attendant speech and language delay if unaddressed. No other organ dysfunction.
• Disease course: Static/stable rather than progressive, based on available data; no reported additional complications (vestibular symptoms, balance problems) despite the structural inner-ear anomaly — vestibular function was specifically documented as preserved.
• Recovery potential/treatment response: With early identification (newborn screening) and appropriate intervention (hearing aids trial, then cochlear implantation given the profound/neuropathy phenotype and poor expected benefit from amplification alone), speech-language outcomes can be substantially improved, though outcomes in common-cavity-deformity ears are documented in the general cochlear-implant literature to be worse on average than implantation in structurally normal cochleae (see Treatment, below) — no DFNB108-specific implant outcome data exist; this is an inference from the general common-cavity-deformity literature.
• Prognostic factors: Timing of diagnosis and intervention (implantation) is the major modifiable prognostic factor for language outcomes, as with any prelingual profound SNHL; the structural common-cavity anomaly itself is a general negative prognostic factor for cochlear-implant electrode-neural interface efficacy.

12. Treatment

Pharmacotherapy: None — there is no drug therapy for DFNB108; it is a structural/developmental sensorineural hearing loss, not a treatable inflammatory, metabolic, or channelopathic process.

Advanced therapeutics (gene therapy, RNA-based therapy): None developed or in trials specific to ROR1-related deafness. (Note: ROR1-targeted therapeutics — monoclonal antibodies such as cirmtuzumab, and ROR1-directed CAR-T cell therapies — exist in active clinical development, but these target somatic ROR1 overexpression in malignancy (e.g., CLL, mantle cell lymphoma) and are wholly unrelated to the germline hearing-loss mechanism; they must not be conflated with a treatment for DFNB108.)

Devices/surgical/interventional (the actual standard of care for this phenotype): - Hearing aids: First-line trial for amplification, though likely of limited benefit given the auditory-neuropathy component (poor benefit from amplification is typical when neural synchrony/transmission, not just cochlear amplification, is impaired). - Cochlear implantation: The most relevant intervention given profound bilateral SNHL with an auditory-neuropathy pattern and common-cavity malformation. Suggested NCIT term: NCIT:C15329 (Surgical Procedure) for treatment_term, with preferred_term capturing "cochlear implantation," and (per the dismech device-binding convention) a qualifiers predicate-value pair for NCIT:C157820 (Cochlear Implant) as the device, following the pattern used in other inner-ear malformation entries (e.g., Jervell and Lange-Nielsen Syndrome 1, Labyrinthitis). General common-cavity-deformity literature (not DFNB108-specific) reports overall poorer — but still meaningful — auditory performance and speech-intelligibility gains post-implantation compared with structurally normal ears; trans-mastoid labyrinthotomy is a commonly used surgical approach, and electrode-to-cavity-wall contact is an important technical determinant of outcome in these malformed cavities. - Speech and language therapy / early intervention (NCIT:C159273 Speech Therapy): Central to management given the expected speech-language delay from prelingual profound deafness. - Genetic counseling (NCIT:C15240): Recommended for the family given the autosomal recessive inheritance and consanguinity, including recurrence-risk counseling (25% recurrence risk for future pregnancies of carrier parents) and discussion of prenatal/carrier testing options for at-risk relatives.

Experimental/clinical trials: No NCT-registered clinical trial for DFNB108 specifically was identified.

Treatment strategy: Standard hereditary-profound-SNHL pathway — newborn screening → confirmatory audiologic/electrophysiologic testing (revealing the auditory-neuropathy pattern) → temporal bone imaging (revealing common cavity) → genetic diagnosis → hearing aid trial (likely limited benefit) → cochlear implantation as definitive intervention, ideally early in infancy to optimize the critical period for spoken-language development → ongoing speech-language therapy and audiologic follow-up.

13. Prevention

• Primary prevention: Not applicable in the classic sense (no modifiable exposure to avoid); the only "primary prevention" lever is reproductive/genetic — carrier testing and reproductive counseling in families with a known pathogenic ROR1 allele, and general avoidance of consanguineous union is a population-level (not disease-specific) recommendation relevant to reducing recessive-disease burden broadly.
• Secondary prevention (early detection): Universal newborn hearing screening (OAE + AABR) is the key secondary-prevention/early-detection tool — critically, because this disorder produces a "pass" pattern on OAE-only screening protocols (auditory neuropathy spares outer hair cell/cochlear amplifier function), screening programs that rely on OAE alone without AABR risk missing this phenotype; AABR-inclusive protocols (as used in most modern universal newborn hearing screening programs) are essential for detection.
• Genetic/carrier screening: Given the ultra-rarity and family-specific nature of the reported variant, population carrier screening is not currently feasible or recommended; testing is appropriate for at-risk relatives once a familial variant is identified, and preimplantation genetic diagnosis / prenatal testing could be offered to carrier couples on request.
• Genetic counseling: As above — 25% recurrence risk per pregnancy for two carrier parents; standard autosomal recessive counseling framework.
• Public health/environmental interventions: Not applicable (no environmental risk factor to mitigate).
• Prophylaxis: None.

14. Other Species / Natural Disease

• Taxonomy: ROR1 orthologs are highly conserved; the relevant model species is mouse (Mus musculus, NCBITaxon:10090).
• Gene ortholog: Ror1 (mouse), MGI:1347520, NCBI Gene (mouse Ror1) — direct ortholog of human ROR1, used to generate the knockout model central to mechanistic understanding.
• Naturally occurring disease in other species: No naturally occurring (spontaneous) Ror1-associated deafness has been reported in companion animals or wildlife (unlike, e.g., some other deafness genes with recognized veterinary counterparts in dogs); the only Ror1-deficient animal model identified is an engineered laboratory knockout mouse, not a spontaneously occurring veterinary disease. No OMIA (Online Mendelian Inheritance in Animals) entry for a natural ROR1-associated deafness was found in this search.
• Comparative biology: The mouse Ror1 knockout recapitulates the core human phenotype components — profound deafness, cochlear structural anomaly (shortened/under-coiled cochlea, analogous in principle to the human common-cavity malformation, though not anatomically identical), and afferent innervation defects — while diverging in that mouse vestibular anatomy and function are preserved, mirroring (and here directly informing/confirming) the preserved vestibular function seen in the human patients.
• Zoonotic potential/cross-species susceptibility: Not applicable (non-infectious, monogenic disorder).

15. Model Organisms

Primary model: Ror1-knockout mouse (MGI:1347520)

• Model type: Mammalian, genetic knockout (constitutive loss-of-function, not a knock-in of the specific human R736T missense allele — an important fidelity caveat, since it models complete loss of ROR1 function rather than the specific partial-trafficking-defect mechanism of the human missense variant).
• Phenotype recapitulation:
• High-fidelity recapitulation: Severe deafness; cochlear structural anomaly (under-coiled, shortened cochlea, with increased hair-cell density toward the apex consistent with impaired convergent extension); spiral ganglion neuron axon fasciculation defects; impaired/absent type I afferent synapses onto inner hair cells (postsynaptic glutamate receptor clusters not detected); aberrant type II afferent projections through the sensory epithelium; preserved otoacoustic emissions (directly mirroring the human auditory-neuropathy electrophysiologic signature); normal vestibular anatomy and function (no circling behavior, normal rotarod performance) — directly mirroring the human patients' preserved balance.
• Partial/uncertain correspondence: Organ of Corti width appears unaffected; stereociliary bundle orientation is normal at P5 in the mouse — the mouse model's cochlear malformation (shortened/under-coiled duct) is not anatomically identical to the human "common cavity" (complete fusion of cochlea and vestibule), representing a species/anatomical-scale divergence worth flagging as a PROXY_QUANTITY or BOUNDARY_OMISSION-type divergence if curated under the dismech modeled_mechanisms framework: the model demonstrates a cochlear coiling/morphogenesis defect and an SGN innervation defect (both at the tissue/cellular scale) that are used to explain, by inference, the human common-cavity structural anomaly and auditory-neuropathy phenotype — but the mouse model was generated as a constitutive null, not a knock-in of the exact patient variant, so it tests loss of ROR1 function generally rather than the specific partial-trafficking-defective allele found in the family.
• Model limitations: (1) Constitutive knockout vs. patient-specific missense knock-in — mechanistic fidelity to the precise molecular lesion (partial membrane-trafficking defect) is inferred, not proven, since the mouse model was not engineered to carry the R736T-equivalent allele; (2) the mouse cochlear malformation (shortened/under-coiled duct) is not a direct anatomical phenocopy of the human common-cavity deformity (complete cochleovestibular fusion) — an interspecies anatomical-scale/severity divergence; (3) no independent human inner-ear histopathology exists to confirm that the SGN innervation defects seen in mouse actually occur identically in the human patients (inaccessible tissue) — this is an upward extrapolation from a cellular/tissue-scale mouse observation to an inferred human mechanism.
• Applications: The model has been used to dissect the WNT5A–ROR1–NF-κB signaling axis in cochlear afferent innervation and duct morphogenesis, and to establish that ROR1 loss produces an auditory-neuropathy-type electrophysiologic signature (preserved OAE, disrupted neural transmission) analogous to the human presentation.
• Resources: MGI:1347520 (Ror1); International Mouse Phenotyping Consortium (IMPC) gene page for Ror1 (mousephenotype.org) — for anyone seeking additional standardized phenotyping data beyond the primary research report.

Other model systems: No zebrafish, Drosophila, C. elegans, yeast, iPSC-derived, or organoid model of ROR1-associated hearing loss was identified in this search. The MDCK II (Madin-Darby Canine Kidney) cell transfection system used for the membrane-trafficking and NF-κB signaling assays is an in vitro heterologous cell-line model, not a disease-relevant inner-ear cell system — useful for testing the specific variant's biochemical/trafficking consequence, but not for recapitulating tissue-level auditory phenotypes.

Summary Table of Key Ontology/Identifier Suggestions for Curation

Important evidentiary caveats for curation

1. Single-family disease. Essentially all clinical/phenotypic content in Sections 3, 7–11 traces to one consanguineous Turkish kindred (2 affected siblings) reported in a single primary paper (PMID:27162350). No independent replication cohort was found in this search — treat any "typically" or frequency-style statement as n=2, not a population estimate.
2. OMIM direct-access limitation. Both OMIM URLs (entry #617654 and its Clinical Synopsis) returned HTTP 403 to direct WebFetch in this session; the content attributed to OMIM above was reconstructed from third-party search-engine cached excerpts and cross-referenced against the PNAS primary paper and ClinVar. Before finalizing any dismech YAML entry, the exact OMIM clinical synopsis wording and the PNAS full-text (Methods/Results, particularly exact family pedigree structure, precise electrophysiology traces, and any additional case detail) should be independently re-verified from primary sources (e.g., via just fetch-reference PMID:27162350 and direct OMIM/PNAS access) rather than relying on this search-engine-mediated report.
3. PubMed MCP tool access was denied by permission in this session, so full abstract text and citation-linked metadata for PMID:27162350 could not be independently confirmed beyond what surfaced through general web search; the PMID itself is corroborated by multiple independent search results (PubMed, PNAS, ClinVar) and should be considered reliable, but exact quoted abstract text should be pulled directly before use as a snippet: in any evidence item.

Sources: - 617654 - DEAFNESS, AUTOSOMAL RECESSIVE 108; DFNB108 - OMIM - Clinical Synopsis - #617654 - OMIM - 602336 - RECEPTOR TYROSINE KINASE-LIKE ORPHAN RECEPTOR 1; ROR1 - OMIM - ROR1 is essential for proper innervation of auditory hair cells and hearing in humans and mice - PubMed (PMID:27162350) - ROR1 is essential for proper innervation of auditory hair cells and hearing in humans and mice - PNAS - hearing loss, autosomal recessive 108 - NORD/MONDO/GARD - NM_005012.4(ROR1):c.2207G>C (p.Arg736Thr) AND Hearing loss, autosomal recessive 108 - ClinVar - VCV000437889.1 - ClinVar - ROR1 Gene - GeneCards - Ror1 MGI Mouse Gene Detail - MGI:1347520 - Analysis of Long-Term Cochlear Implantation Outcomes and Correlation With Imaging Characteristics in Patients With Common Cavity Deformity - PMC

Reference Validation

Checked with linkml-reference-validator 0.2.1.

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

• CL:0002131 (2 mentions) - the report calls it "auditory hair cell / inner hair cell — verify exact CL ID"; CL calls it regular ventricular cardiac myocyte
• CL:0002062 (2 mentions) - the report calls it "outer hair cell — verify"; CL calls it pulmonary alveolar type 1 cell
• UBERON:0001846 (2 mentions) - the report calls it "cochlea"; UBERON calls it internal ear
• UBERON:0002105 (1 mention) - the report calls it "inner ear"; UBERON calls it vestibulo-auditory system

Terms named inconsistently

The report gives these identifiers more than one name of its own:

• MGI:1347520 - called "Ror1", "mouse Ror1"

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: MGI, OMIM.