Autosomal Recessive Nonsyndromic Hearing Loss 79

Mendelian MONDO:0013215 Pathograph 12 Show in embeddings browser Autosomal Recessive Nonsyndromic Hearing Loss

DFNB79 is autosomal recessive nonsyndromic sensorineural hearing loss caused by biallelic truncating variants in TPRN, which encodes taperin. Every human allele reported so far is a frameshift or nonsense change in the first coding exon, so the disease is studied entirely through protein loss rather than through a graded allelic series. Taperin sits at the taper: the narrowed base of the hair cell stereocilium, where the rod pivots against the cuticular plate when sound deflects it. That address was how the protein got its name, and it puts DFNB79 in the same structural compartment as the CLIC5 disease already curated here (DFNB103) - the two proteins are physical partners, and super-resolution imaging shows TPRN, CLIC5 and PTPRQ arranged as concentric rings around the actin core at the taper. What taperin does there took fifteen years to establish. It is an F-actin bundler. Its N-terminal region cross-links actin filaments into bundles that are notably bendable rather than rigid, which is the property a pivot point needs, and it binds the membrane receptor PTPRQ, tying the actin core to the overlying plasma membrane. Losing it does not stop stereocilia being built. Bundles form, and then come apart: rootlets warp, TRIOBP-5 and ANKRD24 disappear from the rootlets of the shortest row, stereocilia are pruned, retract asynchronously and fuse, and inner hair cells later accumulate abnormal endosome-like vesicles and acquire efferent contacts on the cell body that normally exist only in immature or damaged cochleae. This is a maintenance disease, not a morphogenesis disease. Two features separate DFNB79 from its taper-region neighbour DFNB103, and both are negative findings that should not be overwritten by analogy. First, the vestibular system is spared: Tprn-null mice have no circling or head bobbing and no significant vestibular evoked potential deficit through two months, and the affected children in whom balance was formally tested had normal Romberg and tandem gait. CLIC5 loss, by contrast, causes vestibular areflexia in patients and florid circling in mice. Second, the human hearing phenotype is inconsistent in a way that is not explained by allele. The same c.42_52del11 null allele produced stable severe hearing loss into the third decade in a Moroccan family, severe-to-profound loss in one Pakistani family, and progressive loss in another; the authors who found the discordance proposed a genetic modifier and nobody has mapped it. Gene replacement is a live preclinical prospect and a dosage problem at the same time. AAV delivery of Tprn at an appropriate level restores the rings and rescues hearing in Tprn knockout mice - but overexpressing taperin is itself pathogenic, causing excessive actin bundling, extra stereocilia rows, over-elongation and degeneration. Too little and too much both destroy the bundle, which is an unusual constraint for a recessive loss-of-function disease and the central practical question this entry records.

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1
Mappings
1
Inheritance
5
Pathophys.
3
Phenotypes
2
Gaps
12
Pathograph
1
Genes
3
Medical Actions
3
Models
15
References
1
Deep Research
🔗

Mappings

MONDO
MONDO:0013215 autosomal recessive nonsyndromic hearing loss 79
skos:exactMatch MONDO
👪

Inheritance

1
Autosomal recessive HP:0000007
Homozygous truncating TPRN alleles in consanguineous Pakistani and Moroccan pedigrees, with a separate homozygous single-base deletion in a Dutch family. All four founding alleles are truncating and all lie in the first coding exon.
Autosomal recessive inheritance
Show evidence (2 references)
PMID:20170899 SUPPORT Human Clinical
"Evaluation of the other three DFNB79-linked families identified three additional frameshift mutations, for a total of four truncating alleles of this gene."
Four independent truncating alleles segregating recessively across four linked families, which is what establishes the inheritance mode rather than a single consanguineous pedigree.
PMID:20170898 SUPPORT Human Clinical
"By sequencing of 62 positional candidate genes of the critical region, we identified a causative homozygous 11 bp deletion, c.42_52del, in the TPRN gene in all seven affected individuals."
Homozygosity in all seven affected members of a consanguineous Moroccan family, the independent discovery published alongside the Pakistani series.
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Discussions and Knowledge Gaps

2
AAV delivery of Tprn repairs hearing in taperin-null mice, but taperin overexpression is itself used as a tool to destroy the stereocilia rings and causes deafness. Is there a dose of taperin that is therapeutic in a human cochlea, and how would anyone know they were inside it?
HUMAN MODEL MISMATCH tprn_dosage_window_for_gene_replacement
Attached to
animal_models#Tprn knockout mouse treated with AAV-Tprn pathophysiology#Loss of F-Actin Bundling at the Stereocilia Taper genetic#TPRN
Most recessive loss-of-function diseases have a one-sided dosage problem: more protein is better up to normal, and the engineering question is how to deliver enough. Taperin is not like that. In the same study that reports the AAV rescue, exogenous taperin overexpression is one of the two deliberate methods used to disrupt the rings, and it produces stereocilia degeneration and severe hearing loss. An independent group reports the same in wild-type hair cells: excessive F-actin bundling, extra rows, over-elongated and degenerating stereocilia. And from the opposite direction, lowering taperin rescues a different mutant - Grxcr2-null mice, whose lesion is failure to keep taperin confined to the base - which is only coherent if the pathogenic quantity is taperin activity in the wrong place or the wrong amount rather than its absence. The rescue was reported as expression "at an appropriate level", which is the honest description of an experiment in which the level was achievable and not of one in which the window was measured. No dose-response curve bounding it has been published, and AAV transduction of a cochlea is not uniform: the same injection gives different copy numbers in different cells along the cochlear duct, so a dose that is therapeutic at the apex may be toxic at the base. In a disease where too much protein is a known cause of the same lesion, that heterogeneity is not a delivery inconvenience, it is the safety question. Two further mismatches sit underneath. Human onset is prelingual or by about age 2 in every reported family, so a patient's bundles have already deteriorated before a diagnosis exists, while the mouse experiments target a cochlea that is still developing. And taperin is expressed in many tissues and is a nuclear PP1-docking protein recruited to sites of DNA damage; a systemically delivered vector raises questions the cochlear experiments do not address.
Proposed experiments
Dose-response and cochlear-position mapping of AAV-Tprn rescue
exp_dfnb79_aav_tprn_dose_response
Deliver AAV-Tprn to Tprn-null mice across at least five vector doses spanning two orders of magnitude, and at two ages - one before and one after the stereocilia lesion is established - with auditory brainstem response and distortion product otoacoustic emissions as function, scanning electron microscopy of bundle morphology, and single-cell quantification of taperin immunofluorescence and vector genome copy number at apical, middle and basal positions. Include wild-type animals at the top doses to separate overexpression toxicity from incomplete rescue of the null.
Would support
pathophysiology#Loss of F-Actin Bundling at the Stereocilia Taper
Would refute
pathophysiology#Loss of F-Actin Bundling at the Stereocilia Taper
Supporting outcome
  • A reproducible dose band exists in which hearing is restored at every cochlear position without inducing the over-elongation phenotype, and per-cell taperin levels inside that band cluster around the wild-type level, which would make an expression target rather than a vector dose the thing a clinical protocol has to hit.
Refuting outcome
  • No dose rescues the base without over-elongating the apex, because the per-cell expression distribution from a single injection is wider than the therapeutic window, which would mean unregulated AAV replacement is the wrong modality for this gene regardless of vector improvements.
Show evidence (4 references)
PMID:37952086 SUPPORT Model Organism
"The disruption of TPRN rings, triggered by the competitive inhibition of the interaction of TPRN and CLIC5 or exogenous TPRN overexpression, leads to stereocilia degeneration and severe hearing loss."
Overexpression used as a method of causing the disease phenotype, in the same paper that reports the rescue.
PMID:37952086 SUPPORT Model Organism
"restoration of the TPRN rings can rescue the damaged auditory function of Tprn knockout mice by exogenously expressing TPRN at an appropriate level in HCs via promoter recombinant adeno-associated virus (AAV)"
The rescue, with the dosage qualifier the authors attach to it and no published bound on what "appropriate" means.
PMID:40471101 SUPPORT Model Organism
"In contrast, TPRN overexpression causes excessive F-actin bundling, extra rows, and over-elongation of stereocilia during development."
Independent replication of the overexpression toxicity, in a different laboratory and with a different construct.
+ 1 more reference
The same c.42_52del11 null allele produces stable severe hearing loss into the third decade in one family and progressive loss in another. What determines whether DFNB79 progresses?
KNOWLEDGE GAP tprn_identical_allele_discordant_progression
Attached to
phenotypes#Progressive Sensorineural Hearing Impairment phenotypes#Prelingual Severe to Profound Hearing Impairment genetic#TPRN
This is not the ordinary observation that a rare disease is clinically variable. The allele is the same 11 bp deletion in exon 1, it is homozygous in both settings, and it is almost certainly a complete null - so the usual explanation for variable expressivity in a recessive disease, residual protein differing between genotypes, is unavailable here. The authors who found the discordance said so plainly and proposed a genetic modifier. Nobody has looked for it. In the fifteen years since, DFNB79 has been reported in only a handful of families, and no study has assembled enough homozygotes for the same allele to run a modifier search. That is a real obstacle rather than an oversight: modifier mapping needs numbers this disease does not have in any single population. The question is worth keeping open because the answer would be actionable in a way the diagnosis currently is not. A family told that their child is homozygous for c.42_52del11 cannot be told whether the loss will stay where it is or progress to profound, which is exactly the information that determines when to consider implantation and how often to re-test. It also bears on the mechanism: something that modifies the rate of a rootlet-maintenance failure is a candidate for the same protective role in commoner acquired progressive hearing loss. The obvious first candidates are the other taper-region proteins the pathophysiology section already names - CLIC5, PTPRQ, TRIOBP, ANKRD24, GRXCR2 - since taperin's function is defined by that complex and GRXCR2 dosage is already known to change what taperin does. Testing them requires only sequencing existing DFNB79 families, not new recruitment.
Proposed experiments
Targeted sequencing of taper-complex genes in discordant DFNB79 homozygotes
exp_dfnb79_taper_complex_modifier_screen
Sequence CLIC5, PTPRQ, TRIOBP, ANKRD24, GRXCR2, RDX and MYO6 in all available individuals homozygous for TPRN c.42_52del11 from the Moroccan and both Pakistani families, together with serial audiograms defining each individual as progressive or stable, and test whether any variant or haplotype in these genes segregates with the progressive course across families rather than within one of them.
Would support
phenotypes#Progressive Sensorineural Hearing Impairment
Would refute
phenotypes#Progressive Sensorineural Hearing Impairment
Supporting outcome
  • A variant in one of the taper-complex genes tracks with progression across families carrying the same TPRN null, which would give the counselling answer and would identify the complex as the site of the rate-limiting step.
Refuting outcome
  • No taper-complex variant distinguishes progressive from stable individuals, which would move the search to genome-wide modifiers or to non-genetic determinants such as noise exposure history, and would mean the complex hypothesis had been tested rather than left as a plausible guess.
Show evidence (3 references)
PMID:23340767 SUPPORT Human Clinical
"In contrast to the previously reported individuals affected by the same mutation, hearing loss is likely to be progressive in this family."
The discordance itself, on an identical genotype.
PMID:23340767 SUPPORT Human Clinical
"The c.42_52del11 is most likely to be a null mutation. Therefore, its involvement in progressive hearing loss in a family from Pakistan and in stable hearing loss phenotype in another Pakistani and a Moroccan family strongly suggests the presence of a genetic modifier."
The authors' own reasoning, including the step this gap depends on: a null allele leaves no room for a residual-function explanation.
PMID:30380417 SUPPORT INDIRECT Model Organism
"We show that taperin and GRXCR2 form a complex and that taperin is diffused throughout the stereocilia length in Grxcr2-deficient hair cells."
Why GRXCR2 is a named candidate modifier rather than a generic suggestion: it already determines where taperin is. Indirect because no human DFNB79 family has been genotyped at GRXCR2.
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Pathophysiology

5
TPRN Loss of Function
Biallelic truncating TPRN alleles. The reported human spectrum is narrow and unusually uniform. The four DFNB79-linked Pakistani families carry one nonsense allele and three frameshifts; an 11 bp deletion c.42_52del (p.Gly15AlafsX150) accounts for the Moroccan family and, independently, for two Pakistani families; a single-base deletion c.1347delG was found in a Dutch family. Every reported allele lies in exon 1. No missense allele has been reported as causal, so nothing in the human data distinguishes complete absence of taperin from partial function, and the disease is modelled throughout by protein-null alleles.
TPRN hgnc:26894 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TPRN (hgnc:26894). hgnc:26894 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Loss of F-Actin Bundling at the Stereocilia Taper
Show evidence (3 references)
PMID:20170899 SUPPORT Human Clinical
"The remaining variant was a nonsense mutation in a predicted gene, C9orf75, renamed TPRN."
The founding causal allele and the renaming of the gene after its protein product.
PMID:20170898 SUPPORT Human Clinical
"The deletion is located in exon 1 and results in a frameshift and premature protein truncation (p.Gly15AlafsX150)."
The commonest reported allele, its position in the first exon and its truncating consequence.
PMID:23340767 SUPPORT Human Clinical
"To date, all reported mutations of TPRN are located in the first exon"
The clustering of every reported allele in exon 1, which is the observation behind this node's claim that the human spectrum carries no graded series.
Loss of F-Actin Bundling at the Stereocilia Taper
Taperin is an actin cross-linker with a specific address. It encircles the F-actin core at the stereocilium taper, where the rod narrows and pivots, forming concentric rings together with its binding partners CLIC5 and PTPRQ. Purified full-length taperin cross-links F-actin into bundles that are bendable rather than stiff, and this activity maps to the N-terminal region of the protein. Taperin also binds PTPRQ directly, which is how the actin core is tied to the overlying plasma membrane at the taper. The claim that this bundling is what matters for hearing rests on the two directions being tested separately. Deleting taperin removes the rings; competitively blocking the taperin-CLIC5 interaction disrupts them without deleting anything, and produces the same consequence. Two measurements that did not come out as the pivot-point model predicts belong in this node rather than after it. Pivot stiffness of Tprn-null stereocilia was not detectably changed in young postnatal outer hair cells, and those stereocilia were not excessively fragile - they withstood repeated intensive deflections. Mechanotransduction currents in Tprn-null outer hair cells were also largely unaffected. The authors' own reading is that the effect in young postnatal cells may be too subtle for a fluid-jet measurement to resolve, and that the optimisation matters after the onset of hearing and into adulthood; that is a reasonable interpretation, but it means the pivot-flexibility claim in this node's title rests on the bundling biochemistry and the structural phenotype, not on a measured stiffness change. The taper is a compartment rather than a list of proteins, and the dependencies run in every direction between its members. Taperin disperses in CLIC5-null mice; radixin disperses in taperin-null mice; taperin's own dense-core structure is disrupted in RIPOR2-deficient mice, in which it is no longer concentrated at the stereociliary base. Three dismech entries now describe the same compartment from three genes - this one, DFNB103 (CLIC5) and DFNB104 (RIPOR2) - and they should be read as one reciprocal dependency network rather than three separate claims about protein localisation.
cochlear inner hair cell CL:0000589 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cochlear inner hair cell (CL:0000589). CL:0000589 is a cell type from the Cell Ontology. cochlear outer hair cell CL:0000601 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cochlear outer hair cell (CL:0000601). CL:0000601 is a cell type from the Cell Ontology.
actin crosslink formation GO:0051764 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased actin crosslink formation (GO:0051764). GO:0051764 is a biological process from the Gene Ontology. ↓ DECREASED
actin filament binding GO:0051015 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased actin filament binding (GO:0051015). GO:0051015 is a molecular function from the Gene Ontology. ↓ DECREASED
Animal models
Tprn knockout mouse treated with AAV-Tprn Mouse rescues The forward test of the mechanism: restoring the protein restores the structure and the function. That is a stronger argument for the ring being the operative unit than any correlation between its absence and the phenotype.
Downstream
Stereociliary Rootlet Destabilization
Show evidence (10 references)
PMID:40471101 SUPPORT In Vitro
"Purified full-length mouse TPRN cross-links F-actin into bendable bundles reflecting in vivo data. This F-actin-bundling ability is attributed to the TPRN N-terminal region."
The biochemical activity this node names, measured on purified protein, together with the domain it maps to. Graded IN_VITRO: this is a cell-free assay, and the mouse origin of the protein describes the reagent rather than the study design. PMID:40471101 is a mixed-source paper and its in vivo results are carried by separate items.
PMID:40471101 SUPPORT Model Organism
"TPRN interacts with the membrane receptor PTPRQ, connecting the F-actin core to the plasma membrane, stabilizing stereocilia."
The membrane-to-core link, which is the second job taperin does at the taper and the one it shares with the CLIC5 complex.
PMID:40471101 NO_EVIDENCE Model Organism
"we were unable to detect any obvious effects of TPRN deficiency on pivot stiffness of stereocilia, at least in young postnatal OHCs"
Graded NO_EVIDENCE, not REFUTE: the measurement was made and found nothing, and the authors attribute that to the effect being too subtle to resolve at that age rather than absent. Recorded because the mechanical claim this node makes is not supported by a measured stiffness change, and an entry that quoted only the paper's title would imply otherwise.
+ 7 more references
Stereociliary Rootlet Destabilization
The rootlet is the dense actin extension that anchors a stereocilium through its taper into the cuticular plate. Without taperin it is built but not held. Transmission electron microscopy of Tprn-null mice shows rootlets with curved shafts, hollow cores surrounded by loose peripheral dense rings, fragmentation and breakage at the insertion point, and rootlets splayed within the cuticular plate. Two rootlet proteins, TRIOBP-5 and ANKRD24, are progressively lost from the shortest mechanosensory row starting postnatally, and radixin - normally concentrated at the taper - disperses along the stereocilia shafts. The order matters for reading the disease. These are maintenance failures in structures that formed normally, which is why DFNB79 is not a congenital malformation of the bundle.
cochlear inner hair cell CL:0000589 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cochlear inner hair cell (CL:0000589). CL:0000589 is a cell type from the Cell Ontology. cochlear outer hair cell CL:0000601 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cochlear outer hair cell (CL:0000601). CL:0000601 is a cell type from the Cell Ontology.
stereocilium maintenance GO:0120045 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased stereocilium maintenance (GO:0120045). GO:0120045 is a biological process from the Gene Ontology. ↓ DECREASED
Animal models
Tprn CRISPR-null mouse on CBA/CaJ Mouse recapitulates Where the rootlet claim comes from. Rootlet ultrastructure cannot be examined in living patients, so this is not corroboration of a human finding; it is the experiment in which the lesion was defined.
Downstream
Progressive Stereocilia Retraction and Fusion
Show evidence (3 references)
PMID:30159668 SUPPORT Model Organism
"Transmission electron microscopy images of stereociliary bundles in the mutant mice showed some stereociliary rootlets with curved shafts. The central cores of the stereociliary rootlets possessed hollow structures with surrounding loose peripheral dense rings."
The rootlet ultrastructure this node describes, in an independent Tprn-null line.
PMID:30159668 SUPPORT Model Organism
"Radixin, a protein expressed at stereocilia tapering, was abnormally dispersed along the stereocilia shafts in Tprn-null mice."
Partner mislocalisation in the taperin null, the mirror image of the taperin mislocalisation seen in the CLIC5 null.
PMID:40471101 SUPPORT Model Organism
"Stereocilia that lack TPRN develop warped rootlets with gradual loss of TRIOBP-5 and ANKRD24 from mechanosensory rows starting postnatally."
The two rootlet proteins that are lost and the postnatal timing, which is what makes this a maintenance rather than a developmental lesion.
Progressive Stereocilia Retraction and Fusion
Bundles that formed acceptably then deteriorate. Stereocilia are pruned and retract asynchronously, individual stereocilia are missing from the first and third rows, the outer hair cell V shape is distorted, and inner hair cell stereocilia fuse. Scanning electron microscopy in one knockout line traces the inner hair cell course from apparently normal at postnatal day 3 to scattered absence at day 15 and substantial loss by day 30; a second line reports outer hair cell degeneration from day 30. The two published lines disagree about which cell type leads, and both should be read as describing a progressive loss rather than a fixed pattern.
cochlear inner hair cell CL:0000589 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cochlear inner hair cell (CL:0000589). CL:0000589 is a cell type from the Cell Ontology. cochlear outer hair cell CL:0000601 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cochlear outer hair cell (CL:0000601). CL:0000601 is a cell type from the Cell Ontology.
auditory receptor cell stereocilium organization GO:0060088 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased auditory receptor cell stereocilium organization (GO:0060088). GO:0060088 is a biological process from the Gene Ontology. ↓ DECREASED
Animal models
Tprn TALEN knockout mouse Mouse recapitulates The structural lesion, from a normal starting point. Bundles are unremarkable at postnatal day 3 and then deteriorate, which is the sequence the human progressive phenotype implies but which no patient material shows.
Downstream
Inner Hair Cell Synaptic and Vesicular Abnormality
Progressive Sensorineural Hearing Impairment
Show evidence (3 references)
PMID:40471101 SUPPORT Model Organism
"We show that TPRN-deficient mice have progressive deafness characterized by gradual asynchronous retraction and fusion of outer and inner hair cell stereocilia, followed by synaptic abnormalities."
The structural lesion and its ordering relative to the synaptic changes curated on the next node.
PMID:27693694 SUPPORT Model Organism
"scanning electronic microscopy revealed progressive degeneration of inner hair cell stereocilia, from apparently normal at postnatal days 3 (P3) to scattered absence at P15 and further to substantial loss at P30"
The time course in the first published knockout, and the observation that bundles are normal to begin with.
PMID:30159668 SUPPORT Model Organism
"We observed significant hearing loss and progressive degeneration of stereocilia in the outer hair cells of Tprn-null mice starting from postnatal day 30."
The second line, which reports outer rather than inner hair cells leading and a later start. Cited beside the first so the disagreement is visible rather than averaged away.
Inner Hair Cell Synaptic and Vesicular Abnormality
A late change at the opposite pole of the cell from the lesion. Tprn-null inner hair cells accumulate clustered endosome-like vesicles below the nucleus and at postsynaptic sites, and acquire efferent contacts directly on the cell body - axosomatic endings that are normally present only transiently in immature inner hair cells and, in adults, only after cochlear damage or in mutants with no transduction current. Whether this is downstream of the bundle failure or a second job taperin does is not settled. The authors set out both possibilities: progressive loss of transduction current is known to produce exactly these synaptic changes, and taperin separately carries an NPF motif, three predicted YXXphi motifs and a PP1 docking site, all of which point at endocytosis and vesicular trafficking. The edge into this node is therefore curated as indirect, and the alternative is recorded as a knowledge gap rather than being resolved here.
cochlear inner hair cell CL:0000589 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cochlear inner hair cell (CL:0000589). CL:0000589 is a cell type from the Cell Ontology.
Downstream
Progressive Sensorineural Hearing Impairment
Show evidence (2 references)
PMID:40471101 SUPPORT Model Organism
"TEM analyses of P30 Tprn−/− IHCs show numerous membranous vesicles clustered mostly in the cytoplasm below nuclei"
The vesicular accumulation and the age at which it is seen.
PMID:40471101 SUPPORT Model Organism
"In adult mice, these axosomatic IHC contacts from efferent fibers were reported only after damage to the cochlea, in aging mice, or in mutants with no MET currents"
What makes the efferent finding informative: in an adult it is a marker of cochlear damage or of absent transduction, which is why the edge into this node is drawn as indirect rather than as a separate primary lesion.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Autosomal Recessive Nonsyndromic Hearing Loss 79 Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

3
Progressive Sensorineural Hearing Impairment Auditory HP:0008619 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Progressive bilateral sensorineural hearing impairment, annotated with Bilateral sensorineural hearing impairment (HP:0008619), qualified as course progressive. HP:0008619 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
Show evidence (3 references)
PMID:20170898 SUPPORT Human Clinical
"We identified another family with progressive ARNSHL linked to this locus, whose affected members were shown to carry a causative 1 bp deletion (c.1347delG) in exon 1 of TPRN."
The family in which progression was first documented, and its allele.
PMID:23340767 SUPPORT Human Clinical
"The current audiograms of the two affected individuals revealed moderate to profound hearing loss"
The audiometric endpoint in the progressive Pakistani family, against the moderate loss the same two children had at school entry.
PMID:23340767 SUPPORT Human Clinical
"It is interesting to note that the loss in hearing is quite similar at low frequencies, and dramatic shifts of 20-30 dB are observed between the siblings at frequencies of 2-4 KHz."
The frequency asymmetry of the progression, high frequencies moving faster, which matches the mouse course.
Prelingual Severe to Profound Hearing Impairment Auditory HP:0000399 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Prelingual sensorineural hearing impairment (HP:0000399), qualified as severity severe. HP:0000399 is a phenotype from the Human Phenotype Ontology.
Severity: SEVERE
Show evidence (2 references)
PMID:19603065 SUPPORT Human Clinical
"Genetic analysis of an inbred Pakistani family PKDF280, segregating prelingual severe to profound sensorineural hearing loss, provided evidence for a DFNB locus on human chromosome 9q34.3."
The phenotype of the pedigree the locus was named for.
PMID:23340767 SUPPORT Human Clinical
"The same mutation was identified in members of a large Moroccan family suffering a severe degree of hearing loss, which is stable in the third decade of life"
The stable severe presentation on the same allele that elsewhere progresses, which is why both phenotype records are curated rather than one.
Normal Vestibular Function EXCLUDED Vestibular HP:0001751 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is absent Normal vestibular function, annotated with Abnormal vestibular function (HP:0001751). HP:0001751 is a phenotype from the Human Phenotype Ontology.
∅ ABSENT
Show evidence (2 references)
PMID:23340767 SUPPORT Human Clinical
"Tandem walking was normal, and the Romberg test was also negative among affected children, suggesting normal vestibular function."
The only formal human vestibular assessment in a reported DFNB79 family, and its result.
PMID:40471101 SUPPORT INDIRECT Model Organism
"Thus, TPRN is necessary for auditory hair cell function and, at least in the first few months of life, is not necessary for vestibular hair cell function."
The mouse counterpart, quantitative rather than bedside. Indirect with respect to the human claim because it is a different species, and the authors themselves limit it to the first few months of life.
🧬

Genetic Associations

1
TPRN
Gene: TPRN hgnc:26894 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is TPRN (hgnc:26894). hgnc:26894 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (4 references)
PMID:20170899 SUPPORT Human Clinical
"Although TPRN is expressed in many tissues, immunolocalization of the protein product in the mouse cochlea shows prominent expression in the taper region of hair cell stereocilia. Consequently, we named the protein taperin."
The localisation that gave the protein its name, and the observation that expression is not restricted to the ear.
PMID:23213405 SUPPORT In Vitro
"Taperin associates with PP1 through a classic 'RVxF' motif and suppresses the general phosphatase activity of the enzyme."
The biochemical activity outside the ear, which is the basis for the caution about systemic effects of any taperin-directed intervention.
PMID:23213405 SUPPORT In Vitro
"Taperin also shares an ancestral relationship with the cytosolic actin binding protein phostensin, another PP1 interacting partner."
The homology that predicted the actin function years before it was demonstrated biochemically.
+ 1 more reference
💊

Medical Actions

3
Genetic Counselling with Serial Audiometry
Action: genetic counselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is genetic counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. Ontology label: Genetic Counseling NCIT:C15240
Platform: Other
Counselling for a recessive condition with a 25 percent sibling recurrence risk, and repeated rather than single audiometric assessment. Serial testing is the substantive part: the same TPRN allele produces a stable loss in one family and a progressive one in another, so a single audiogram establishes the current threshold and nothing about the trajectory. Where progression occurs it is faster at high frequencies, which is where the follow-up should be looking.
Show evidence (1 reference)
PMID:23340767 SUPPORT Human Clinical
"Thus the same mutation of TPRN can be associated with different thresholds of hearing as well as differences in the stability of the phenotype."
The reason a single assessment is insufficient: the genotype does not fix either the threshold or the trajectory.
Cochlear Implantation
Action: cochlear device implantationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is cochlear device implantation, annotated with Surgical Procedure (NCIT:C15329), qualified as medical device cochlear implant. NCIT:C15329 is a clinical intervention from the NCI Thesaurus. Ontology label: Surgical Procedure NCIT:C15329
Platform: Device
The standard intervention for severe-to-profound sensorineural hearing loss, and the mechanism here argues for it directly. The DFNB79 lesion is inside the hair cell stereocilium: the bundle fails, and the hair cell can no longer convert sound into a receptor potential. An implant stimulates the spiral ganglion electrically and does not need a working bundle, so it operates downstream of everything this entry's pathograph describes. One caveat belongs beside that argument rather than after it. Tprn-null mice develop inner hair cell synaptic and vesicular abnormalities and acquire efferent contacts on the cell body, and the same study raises the possibility of a direct role for taperin in vesicular trafficking rather than a purely secondary consequence of losing transduction. If that turns out to be true in patients, the neural side of the pathway is not entirely spared and implant outcome would be less predictable than the bundle-lesion argument implies. Nobody has looked.
Mechanism Target:
BYPASSES Progressive Stereocilia Retraction and Fusion — Electrical stimulation of the spiral ganglion substitutes for the transduction current a fused or retracted bundle can no longer generate, so the implant works downstream of the node that fails.
Hearing Amplification
Action: hearing aid amplificationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is hearing aid amplification, annotated with Rehabilitation (NCIT:C15315), qualified as medical device hearing aid. NCIT:C15315 is a clinical intervention from the NCI Thesaurus. Ontology label: Rehabilitation NCIT:C15315
Platform: Device
Amplification is the first-line intervention while useful residual hearing remains, which in DFNB79 is most of childhood in the families whose loss begins mild or moderate. Unlike an implant it does not bypass the lesion - it raises the stimulus reaching a bundle that still partly works - so its useful life is bounded by how fast the loss progresses, and that rate is not predictable from the genotype.
Mechanism Target:
Progressive Sensorineural Hearing Impairment — Compensates for the threshold loss by raising the sound pressure reaching a bundle that is degenerating but not yet lost. It does not act on the taper defect or slow the stereocilia degeneration driving it, which is why no treatment_effect value is recorded - the enum's values all assert a change to the mechanism, and amplification makes no such claim.
🔬

Diagnosis

1
TPRN sequencing on recessive nonsyndromic hearing loss panels
DFNB79 is reached by exome sequencing or a deafness panel containing TPRN, after GJB2 has been excluded. Because every reported allele lies in exon 1, sequencing that exon alone was proposed as a cheap first pass in recessive nonsyndromic hearing loss, particularly where there are signs of progression. Vestibular testing does not discriminate - it is normal in DFNB79 - so a progressive recessive loss with normal balance is the clinical shape that should prompt the test, and vestibular involvement argues for a different taper-region gene.
Show evidence (1 reference)
PMID:23340767 SUPPORT Human Clinical
"Sequencing of this exon may be considered in recessively inherited cases of nonsyndromic hearing loss, especially if signs of progression are present"
The explicit testing recommendation and the clinical trigger for it.
📈

Progression

2
Onset
Age: prelingual to about 2 years
Onset is early. In the progressive Pakistani family the parents noticed the loss by age 2; in the founding pedigree and the Moroccan family the loss was prelingual. A newborn hearing screen has not been reported as passed or failed in any DFNB79 family, so this entry does not state whether the disease is detectable at birth.
Show evidence (1 reference)
PMID:23340767 SUPPORT Human Clinical
"According to the parents, the onset of hearing loss was noticed by 2 years of age."
The reported age of recognition in the family with the best-documented history.
Deterioration or stability
Age: childhood to third decade
Where the disease progresses it does so through childhood and adolescence, faster at high frequencies. Where it does not, the loss reported in the Moroccan family remained stable into the third decade. Which course a given family follows is not predictable from the TPRN allele, and serial audiometry is the only way to tell them apart.
Show evidence (1 reference)
PMID:23340767 SUPPORT Human Clinical
"This suggests that hearing at high frequencies worsens rapidly, while loss of hearing at lower frequencies may be more gradual."
The frequency-dependent shape of the progression where it occurs.
📊

Prevalence

2
Worldwide
Cases In Literature Ultra Rare
DFNB79 has been reported in a small number of families - four Pakistani pedigrees linked to the locus, a Moroccan family and a Dutch family in the founding reports, and single additional families since. No population prevalence estimate exists and no rate_per_100000 is recorded, because none has been published; ULTRA_RARE is the qualitative band rather than a numeric conversion.
Show evidence (1 reference)
PMID:23340767 SUPPORT Human Clinical
"The DFNB79 locus harbors TPRN mutations in which have been reported in a few families with deafness."
The size of the reported literature, in the authors' own words.
Consanguineous Pakistani families and sporadic cases with moderate to severe hearing loss
Unknown
A targeted screen of 50 consanguineous multiplex families and 57 sporadic cases from Pakistan found no further DFNB79-linked family and no case homozygous for markers spanning TPRN. That is a negative diagnostic yield in an ascertained cohort, not a population rate, so no prevalence_class or rate_per_100000 is recorded; putting a numeric band here would assert an occurrence estimate the study does not make. The ascertainment also selected for moderate-to-severe rather than progressive loss, which the authors identify as the limitation on what the negative result means.
Show evidence (1 reference)
PMID:23340767 SUPPORT Human Clinical
"This suggests that TPRN is not a significant contributor to moderate to severe hearing loss in the Pakistani population, although its contribution to progressive hearing loss remains to be determined."
The negative screen and the authors' own statement of what it does and does not exclude.
🐁

Animal Models

3
Tprn TALEN knockout mouse
The first taperin knockout, made with TALENs and carrying an 11 bp exon 1 deletion of the same class as the human founding allele. Homozygotes have progressive sensorineural hearing loss on click and tone-burst auditory brainstem response at postnatal days 15, 30 and 60; heterozygotes are indistinguishable from wild type, which matches the recessive human inheritance. Hair cell counts are preserved on phalloidin labelling while the stereocilia themselves degenerate, so the model separates bundle failure from cell death.
Species
Mouse
Genotype
Tprn -/-, 11 bp deletion at nucleotides 177-187 of exon 1
Genes
TPRN hgnc:26894 HUGO Gene Nomenclature Committee (hgnc) Relation: this experimental model concerns this gene This experimental model concerns TPRN (hgnc:26894). hgnc:26894 is a gene from the HUGO Gene Nomenclature Committee.
Publication
PMID:27693694
Pathograph links
Progressive Stereocilia Retraction and Fusion recapitulates fidelity: high The structural lesion, from a normal starting point. Bundles are unremarkable at postnatal day 3 and then deteriorate, which is the sequence the human progressive phenotype implies but which no patient material shows.
Limitations: The mouse course runs over weeks where the human one runs over years, and this line reports inner hair cell stereocilia leading with outer hair cells much less severely affected, which is the opposite emphasis to the CRISPR null line. The disagreement is unresolved, so neither line should be treated as fixing which cell type fails first in patients. The allele is a protein-null; whether human truncating alleles in exon 1 behave identically has not been shown at the protein level in patients.
Readouts
Inner hair cell stereocilia by scanning electron microscopy
Direction: DECREASED
Interpretation: Stereocilia are progressively lost from normal-appearing bundles between postnatal days 3 and 30.
Show evidence (1 reference)
PMID:27693694 SUPPORT Model Organism
"scanning electronic microscopy revealed progressive degeneration of inner hair cell stereocilia, from apparently normal at postnatal days 3 (P3) to scattered absence at P15 and further to substantial loss at P30"
The structural measurement and its time course.
Auditory brainstem response threshold
Direction: INCREASED
Interpretation: Thresholds rise across postnatal days 15, 30 and 60 - hearing gets worse, so the threshold value goes up.
Show evidence (1 reference)
PMID:27693694 SUPPORT Model Organism
"Homozygous TPRN-/- mice exhibited progressive sensorineural hearing loss as reflected by auditory brainstem response to both click and tone burst stimuli at postnatal days 15 (P15), 30 (P30), and 60 (P60)."
The functional measurement behind this readout and the ages tested.
Show evidence (1 reference)
PMID:27693694 SUPPORT Model Organism
"Heterozygous TPRN+/- mice showed apparently normal auditory phenotypes to their wide-type (WT) littermates."
The recessive behaviour of the mouse allele, which is what makes the line informative for a recessive human disease rather than for a dominant one.
Tprn CRISPR-null mouse on CBA/CaJ
An independent null on a background without the age-related hearing loss confounder that complicates other strains. This is the line in which the rootlet lesion was described: curved rootlet shafts, hollow central cores with loose peripheral dense rings, dispersal of radixin along the stereocilia shafts, and reduced radixin and beta-actin levels. Outer hair cell stereocilia degenerate from postnatal day 30.
Species
Mouse
Genotype
Tprn-null, CRISPR/Cas9-generated, CBA/CaJ background
Genes
TPRN hgnc:26894 HUGO Gene Nomenclature Committee (hgnc) Relation: this experimental model concerns this gene This experimental model concerns TPRN (hgnc:26894). hgnc:26894 is a gene from the HUGO Gene Nomenclature Committee.
Publication
PMID:30159668
Pathograph links
Stereociliary Rootlet Destabilization recapitulates fidelity: high Where the rootlet claim comes from. Rootlet ultrastructure cannot be examined in living patients, so this is not corroboration of a human finding; it is the experiment in which the lesion was defined.
Limitations: The rootlet abnormalities were described qualitatively from transmission electron micrographs rather than quantified, and the radixin and beta-actin reductions are whole-cochlea measurements that cannot localise the loss to the taper. The line reports outer hair cells degenerating first, which the TALEN line does not.
Readouts
Rootlet ultrastructure by transmission electron microscopy
Direction: ALTERED
Interpretation: Rootlets are present but malformed - curved shafts, hollow cores, loose peripheral rings - so the defect is in maintaining the structure rather than in building it.
Show evidence (1 reference)
PMID:30159668 SUPPORT Model Organism
"Transmission electron microscopy images of stereociliary bundles in the mutant mice showed some stereociliary rootlets with curved shafts. The central cores of the stereociliary rootlets possessed hollow structures with surrounding loose peripheral dense rings."
The ultrastructural measurement behind this readout.
Radixin distribution along stereocilia
Direction: ALTERED
Interpretation: Radixin leaves the taper and spreads along the shaft, which is the partner-protein signature of a failed taper complex.
Show evidence (1 reference)
PMID:30159668 SUPPORT Model Organism
"Radixin, a protein expressed at stereocilia tapering, was abnormally dispersed along the stereocilia shafts in Tprn-null mice."
The immunolocalisation measurement behind this readout.
Show evidence (1 reference)
PMID:30159668 SUPPORT Model Organism
"The generated Tprn-null mice are ideal models of human hereditary deafness DFNB79."
The authors' own claim for the line's relevance. Recorded as their assessment rather than endorsed - the limitations above are the reasons this entry does not repeat the word "ideal".
Tprn knockout mouse treated with AAV-Tprn
A gene-replacement experiment whose result cuts two ways. Delivering Tprn by AAV at an appropriate level restores the concentric rings at the taper and repairs hearing in Tprn knockout mice. In the same study, overexpressing taperin is one of the two manipulations used to break the rings deliberately - the other being competitive inhibition of the taperin-CLIC5 interaction - and it produces stereocilia degeneration and severe hearing loss on its own.
Species
Mouse
Genotype
Tprn knockout treated with promoter-driven recombinant AAV carrying Tprn
Genes
TPRN hgnc:26894 HUGO Gene Nomenclature Committee (hgnc) Relation: this experimental model concerns this gene This experimental model concerns TPRN (hgnc:26894). hgnc:26894 is a gene from the HUGO Gene Nomenclature Committee.
Publication
PMID:37952086
Pathograph links
Loss of F-Actin Bundling at the Stereocilia Taper rescues fidelity: moderate The forward test of the mechanism: restoring the protein restores the structure and the function. That is a stronger argument for the ring being the operative unit than any correlation between its absence and the phenotype.
Limitations: Rescue is conditional on dose. The same paper uses taperin overexpression as a tool to destroy the rings, so the therapeutic window is bounded above as well as below, and no dose-response curve mapping that window has been published. The experiment is also a mouse cochlea injected under laboratory conditions; nothing here addresses the age at which a patient with an already-degenerated bundle could be treated, and the human onset is prelingual or early childhood in every reported family.
Readouts
Auditory function after AAV-Tprn delivery
Direction: RESTORED
Interpretation: Hearing is repaired when the rings are restored, tying the auditory outcome to the structure rather than to the presence of the protein anywhere in the cell.
Show evidence (1 reference)
PMID:37952086 SUPPORT Model Organism
"restoration of the TPRN rings can rescue the damaged auditory function of Tprn knockout mice by exogenously expressing TPRN at an appropriate level in HCs via promoter recombinant adeno-associated virus (AAV)"
The rescue measurement, including the authors' own qualifier "at an appropriate level", which is the dosage constraint this model is curated to record.
Show evidence (1 reference)
PMID:37952086 SUPPORT Model Organism
"TPRN ring restoration in stereocilia by AAV-Tprn effectively repairs damaged hearing, which lays the foundation for the clinical application of AAV-mediated gene therapy in patients with TPRN mutation."
The authors' statement of translational intent, recorded as their claim. The overexpression toxicity documented in the same study is why this entry treats it as a foundation rather than a plan.
{ }

Source YAML

click to show 
name: Autosomal Recessive Nonsyndromic Hearing Loss 79
category: Mendelian
creation_date: "2026-09-01T00:00:00Z"
synonyms:
- DFNB79
- autosomal recessive nonsyndromic deafness 79
- autosomal recessive nonsyndromic deafness type 79
- deafness, autosomal recessive 79
- deafness, autosomal recessive type 79
- autosomal recessive deafness 79
- autosomal recessive nonsyndromic deafness caused by mutation in TPRN
- TPRN autosomal recessive nonsyndromic deafness
description: >-
  DFNB79 is autosomal recessive nonsyndromic sensorineural hearing loss caused by biallelic
  truncating variants in TPRN, which encodes taperin. Every human allele reported so far is
  a frameshift or nonsense change in the first coding exon, so the disease is studied
  entirely through protein loss rather than through a graded allelic series.

  Taperin sits at the taper: the narrowed base of the hair cell stereocilium, where the
  rod pivots against the cuticular plate when sound deflects it. That address was how the
  protein got its name, and it puts DFNB79 in the same structural compartment as the CLIC5
  disease already curated here (DFNB103) - the two proteins are physical partners, and
  super-resolution imaging shows TPRN, CLIC5 and PTPRQ arranged as concentric rings around
  the actin core at the taper.

  What taperin does there took fifteen years to establish. It is an F-actin bundler. Its
  N-terminal region cross-links actin filaments into bundles that are notably bendable
  rather than rigid, which is the property a pivot point needs, and it binds the membrane
  receptor PTPRQ, tying the actin core to the overlying plasma membrane. Losing it does not
  stop stereocilia being built. Bundles form, and then come apart: rootlets warp, TRIOBP-5
  and ANKRD24 disappear from the rootlets of the shortest row, stereocilia are pruned,
  retract asynchronously and fuse, and inner hair cells later accumulate abnormal
  endosome-like vesicles and acquire efferent contacts on the cell body that normally exist
  only in immature or damaged cochleae. This is a maintenance disease, not a morphogenesis
  disease.

  Two features separate DFNB79 from its taper-region neighbour DFNB103, and both are
  negative findings that should not be overwritten by analogy. First, the vestibular system
  is spared: Tprn-null mice have no circling or head bobbing and no significant vestibular
  evoked potential deficit through two months, and the affected children in whom balance
  was formally tested had normal Romberg and tandem gait. CLIC5 loss, by contrast, causes
  vestibular areflexia in patients and florid circling in mice. Second, the human hearing
  phenotype is inconsistent in a way that is not explained by allele. The same
  c.42_52del11 null allele produced stable severe hearing loss into the third decade in a
  Moroccan family, severe-to-profound loss in one Pakistani family, and progressive loss in
  another; the authors who found the discordance proposed a genetic modifier and nobody has
  mapped it.

  Gene replacement is a live preclinical prospect and a dosage problem at the same time.
  AAV delivery of Tprn at an appropriate level restores the rings and rescues hearing in
  Tprn knockout mice - but overexpressing taperin is itself pathogenic, causing excessive
  actin bundling, extra stereocilia rows, over-elongation and degeneration. Too little and
  too much both destroy the bundle, which is an unusual constraint for a recessive
  loss-of-function disease and the central practical question this entry records.
disease_term:
  preferred_term: autosomal recessive nonsyndromic hearing loss 79
  term:
    id: MONDO:0013215
    label: autosomal recessive nonsyndromic hearing loss 79
parents:
- Autosomal Recessive Nonsyndromic Hearing Loss
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0013215
      label: autosomal recessive nonsyndromic hearing loss 79
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
references:
- reference: PMID:20170899
  title: "Targeted capture and next-generation sequencing identifies C9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness DFNB79."
- reference: PMID:20170898
  title: "Mutations in TPRN cause a progressive form of autosomal-recessive nonsyndromic hearing loss."
- reference: PMID:19603065
  title: "DFNB79: reincarnation of a nonsyndromic deafness locus on chromosome 9q34.3."
- reference: PMID:23340767
  title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
- reference: PMID:40471101
  title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
- reference: PMID:37952086
  title: "Critical role of TPRN rings in the stereocilia for hearing."
- reference: PMID:30159668
  title: "Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice."
- reference: PMID:27693694
  title: "Progressive hearing loss and degeneration of hair cell stereocilia in taperin gene knockout mice."
- reference: PMID:24285636
  title: "CLIC5 stabilizes membrane-actin filament linkages at the base of hair cell stereocilia in a molecular complex with radixin, taperin, and myosin VI."
- reference: PMID:30380417
  title: "GRXCR2 Regulates Taperin Localization Critical for Stereocilia Morphology and Hearing."
- reference: PMID:35752427
  title: "Reducing Taperin Expression Restores Hearing in Grxcr2 Mutant Mice."
- reference: PMID:23213405
  title: "Taperin (c9orf75), a mutated gene in nonsyndromic deafness, encodes a vertebrate specific, nuclear localized protein phosphatase one alpha (PP1alpha) docking protein."
- reference: PMID:27269051
  title: "Murine Fam65b forms ring-like structures at the base of stereocilia critical for mechanosensory hair cell function."
- reference: PMID:32631815
  title: "A RIPOR2 in-frame deletion is a frequent and highly penetrant cause of adult-onset hearing loss."
- reference: PMID:34026762
  title: "N-Terminus of GRXCR2 Interacts With CLIC5 and Is Essential for Auditory Perception."
inheritance:
- name: Autosomal recessive
  description: >-
    Homozygous truncating TPRN alleles in consanguineous Pakistani and Moroccan pedigrees,
    with a separate homozygous single-base deletion in a Dutch family. All four founding
    alleles are truncating and all lie in the first coding exon.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: PMID:20170899
    reference_title: "Targeted capture and next-generation sequencing identifies C9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness DFNB79."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Evaluation of the other three DFNB79-linked families identified three additional frameshift mutations, for a total of four truncating alleles of this gene."
    explanation: >-
      Four independent truncating alleles segregating recessively across four linked
      families, which is what establishes the inheritance mode rather than a single
      consanguineous pedigree.
  - reference: PMID:20170898
    reference_title: "Mutations in TPRN cause a progressive form of autosomal-recessive nonsyndromic hearing loss."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "By sequencing of 62 positional candidate genes of the critical region, we identified a causative homozygous 11 bp deletion, c.42_52del, in the TPRN gene in all seven affected individuals."
    explanation: >-
      Homozygosity in all seven affected members of a consanguineous Moroccan family, the
      independent discovery published alongside the Pakistani series.
pathophysiology:
- name: TPRN Loss of Function
  description: >-
    Biallelic truncating TPRN alleles. The reported human spectrum is narrow and unusually
    uniform. The four DFNB79-linked Pakistani families carry one nonsense allele and three
    frameshifts; an 11 bp deletion c.42_52del (p.Gly15AlafsX150) accounts for the Moroccan
    family and, independently, for two Pakistani families; a single-base deletion c.1347delG
    was found in a Dutch family. Every reported allele lies in exon 1. No missense allele
    has been reported as causal, so nothing in the human data distinguishes complete absence
    of taperin from partial function, and the disease is modelled throughout by protein-null
    alleles.
  biological_scale: MOLECULAR
  genes:
  - preferred_term: TPRN
    term:
      id: hgnc:26894
      label: TPRN
  downstream:
  - target: Loss of F-Actin Bundling at the Stereocilia Taper
    causal_link_type: DIRECT
  evidence:
  - reference: PMID:20170899
    reference_title: "Targeted capture and next-generation sequencing identifies C9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness DFNB79."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The remaining variant was a nonsense mutation in a predicted gene, C9orf75, renamed TPRN."
    explanation: The founding causal allele and the renaming of the gene after its protein product.
  - reference: PMID:20170898
    reference_title: "Mutations in TPRN cause a progressive form of autosomal-recessive nonsyndromic hearing loss."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The deletion is located in exon 1 and results in a frameshift and premature protein truncation (p.Gly15AlafsX150)."
    explanation: >-
      The commonest reported allele, its position in the first exon and its truncating
      consequence.
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "To date, all reported mutations of TPRN are located in the first exon"
    explanation: >-
      The clustering of every reported allele in exon 1, which is the observation behind
      this node's claim that the human spectrum carries no graded series.
- name: Loss of F-Actin Bundling at the Stereocilia Taper
  description: >-
    Taperin is an actin cross-linker with a specific address. It encircles the F-actin core
    at the stereocilium taper, where the rod narrows and pivots, forming concentric rings
    together with its binding partners CLIC5 and PTPRQ. Purified full-length taperin
    cross-links F-actin into bundles that are bendable rather than stiff, and this activity
    maps to the N-terminal region of the protein. Taperin also binds PTPRQ directly, which
    is how the actin core is tied to the overlying plasma membrane at the taper.

    The claim that this bundling is what matters for hearing rests on the two directions
    being tested separately. Deleting taperin removes the rings; competitively blocking the
    taperin-CLIC5 interaction disrupts them without deleting anything, and produces the same
    consequence.

    Two measurements that did not come out as the pivot-point model predicts belong in this
    node rather than after it. Pivot stiffness of Tprn-null stereocilia was not detectably
    changed in young postnatal outer hair cells, and those stereocilia were not excessively
    fragile - they withstood repeated intensive deflections. Mechanotransduction currents in
    Tprn-null outer hair cells were also largely unaffected. The authors' own reading is that
    the effect in young postnatal cells may be too subtle for a fluid-jet measurement to
    resolve, and that the optimisation matters after the onset of hearing and into adulthood;
    that is a reasonable interpretation, but it means the pivot-flexibility claim in this
    node's title rests on the bundling biochemistry and the structural phenotype, not on a
    measured stiffness change.

    The taper is a compartment rather than a list of proteins, and the dependencies run in
    every direction between its members. Taperin disperses in CLIC5-null mice; radixin
    disperses in taperin-null mice; taperin's own dense-core structure is disrupted in
    RIPOR2-deficient mice, in which it is no longer concentrated at the stereociliary base.
    Three dismech entries now describe the same compartment from three genes - this one,
    DFNB103 (CLIC5) and DFNB104 (RIPOR2) - and they should be read as one reciprocal
    dependency network rather than three separate claims about protein localisation.
  biological_scale: MOLECULAR
  cell_types:
  - preferred_term: cochlear inner hair cell
    term:
      id: CL:0000589
      label: cochlear inner hair cell
  - preferred_term: cochlear outer hair cell
    term:
      id: CL:0000601
      label: cochlear outer hair cell
  molecular_functions:
  - preferred_term: actin filament binding
    term:
      id: GO:0051015
      label: actin filament binding
    modifier: DECREASED
  biological_processes:
  - preferred_term: actin crosslink formation
    term:
      id: GO:0051764
      label: actin crosslink formation
    modifier: DECREASED
  downstream:
  - target: Stereociliary Rootlet Destabilization
    causal_link_type: DIRECT
  evidence:
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Purified full-length mouse TPRN cross-links F-actin into bendable bundles reflecting in vivo data. This F-actin-bundling ability is attributed to the TPRN N-terminal region."
    explanation: >-
      The biochemical activity this node names, measured on purified protein, together with
      the domain it maps to. Graded IN_VITRO: this is a cell-free assay, and the mouse origin
      of the protein describes the reagent rather than the study design. PMID:40471101 is a
      mixed-source paper and its in vivo results are carried by separate items.
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "TPRN interacts with the membrane receptor PTPRQ, connecting the F-actin core to the plasma membrane, stabilizing stereocilia."
    explanation: >-
      The membrane-to-core link, which is the second job taperin does at the taper and the
      one it shares with the CLIC5 complex.
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: NO_EVIDENCE
    evidence_source: MODEL_ORGANISM
    snippet: "we were unable to detect any obvious effects of TPRN deficiency on pivot stiffness of stereocilia, at least in young postnatal OHCs"
    explanation: >-
      Graded NO_EVIDENCE, not REFUTE: the measurement was made and found nothing, and the
      authors attribute that to the effect being too subtle to resolve at that age rather
      than absent. Recorded because the mechanical claim this node makes is not supported by
      a measured stiffness change, and an entry that quoted only the paper's title would
      imply otherwise.
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: NO_EVIDENCE
    evidence_source: MODEL_ORGANISM
    snippet: "However, our data show that MET currents are largely unaffected at least in Tprn−/− OHCs."
    explanation: >-
      The second negative, and it constrains the mechanism usefully: whatever taperin loss
      does to hearing, it is not an immediate failure of the transduction channel. That is
      what makes DFNB79 a progressive structural disease rather than a transduction
      channelopathy, and it is the contrast with the tip-complex deafness genes.
  - reference: PMID:37952086
    reference_title: "Critical role of TPRN rings in the stereocilia for hearing."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "we show that the TPRN, together with its binding proteins CLIC5 and PTPRQ, forms concentric rings in the taper region of stereocilia"
    explanation: >-
      The structure itself, resolved by dual STED microscopy. This is the point of contact
      with DFNB103: the same three proteins, the same rings.
  - reference: PMID:37952086
    reference_title: "Critical role of TPRN rings in the stereocilia for hearing."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The disruption of TPRN rings, triggered by the competitive inhibition of the interaction of TPRN and CLIC5 or exogenous TPRN overexpression, leads to stereocilia degeneration and severe hearing loss."
    explanation: >-
      Disrupting the rings without deleting the gene reproduces the phenotype, which is what
      makes the ring structure the functional unit rather than an incidental arrangement.
  - reference: PMID:24285636
    reference_title: "CLIC5 stabilizes membrane-actin filament linkages at the base of hair cell stereocilia in a molecular complex with radixin, taperin, and myosin VI."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Radixin (RDX), protein tyrosine phosphatase receptor Q (PTPRQ), and taperin (TPRN), deafness-associated proteins that also concentrate at the base of stereocilia, were mislocalized in fused stereocilia of jbg mice."
    explanation: >-
      The dependency measured from the CLIC5 side: losing CLIC5 mislocalises taperin. Cited
      here so this entry and the DFNB103 entry rest on the same observation rather than on
      two separate assertions about the taper complex.
  - reference: PMID:27269051
    reference_title: "Murine Fam65b forms ring-like structures at the base of stereocilia critical for mechanosensory hair cell function."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Taperin, a second protein near the taper, forms a dense-core-like structure that is disrupted in the absence of Fam65b."
    explanation: >-
      The dependency measured from the RIPOR2 side. This is the same observation the DFNB104
      entry curates as its taper-compartment readout, cited here so the two entries agree on
      it rather than each asserting it independently.
  - reference: PMID:32631815
    reference_title: "A RIPOR2 in-frame deletion is a frequent and highly penetrant cause of adult-onset hearing loss."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "CLIC5, PTPRQ, MYO6, TPRN, RDX, GRXCR2, and RIPOR2 are described to concentrate and co-function in the taper region and to be crucial for its structure and/or for hair bundle development and maintenance in mice."
    explanation: >-
      The full membership of the taper compartment in one sentence, which is the frame the
      three taper-region dismech entries share. Graded OTHER because it is this paper's
      summary of prior work rather than a measurement it made.
  - reference: PMID:34026762
    reference_title: "N-Terminus of GRXCR2 Interacts With CLIC5 and Is Essential for Auditory Perception."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    directness: INDIRECT
    snippet: "Interestingly, mice harboring this in-frame deletion in Grxcr2 exhibit moderate hearing loss at lower frequencies and severe hearing loss at higher frequencies although the morphogenesis of stereocilia is minimally affected."
    explanation: >-
      Deleting only the CLIC5-binding region of a partner protein causes hearing loss with
      almost no change in stereocilia shape, so the taper complex matters functionally and
      not only structurally. Indirect with respect to TPRN because the genotype perturbed is
      Grxcr2; the same observation is cited by the DFNB103 entry, which is why it is quoted
      identically here.
- name: Stereociliary Rootlet Destabilization
  description: >-
    The rootlet is the dense actin extension that anchors a stereocilium through its taper
    into the cuticular plate. Without taperin it is built but not held. Transmission
    electron microscopy of Tprn-null mice shows rootlets with curved shafts, hollow cores
    surrounded by loose peripheral dense rings, fragmentation and breakage at the insertion
    point, and rootlets splayed within the cuticular plate. Two rootlet proteins, TRIOBP-5
    and ANKRD24, are progressively lost from the shortest mechanosensory row starting
    postnatally, and radixin - normally concentrated at the taper - disperses along the
    stereocilia shafts.

    The order matters for reading the disease. These are maintenance failures in structures
    that formed normally, which is why DFNB79 is not a congenital malformation of the bundle.
  biological_scale: CELLULAR
  cell_types:
  - preferred_term: cochlear inner hair cell
    term:
      id: CL:0000589
      label: cochlear inner hair cell
  - preferred_term: cochlear outer hair cell
    term:
      id: CL:0000601
      label: cochlear outer hair cell
  biological_processes:
  - preferred_term: stereocilium maintenance
    term:
      id: GO:0120045
      label: stereocilium maintenance
    modifier: DECREASED
  downstream:
  - target: Progressive Stereocilia Retraction and Fusion
    causal_link_type: DIRECT
  evidence:
  - reference: PMID:30159668
    reference_title: "Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Transmission electron microscopy images of stereociliary bundles in the mutant mice showed some stereociliary rootlets with curved shafts. The central cores of the stereociliary rootlets possessed hollow structures with surrounding loose peripheral dense rings."
    explanation: The rootlet ultrastructure this node describes, in an independent Tprn-null line.
  - reference: PMID:30159668
    reference_title: "Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Radixin, a protein expressed at stereocilia tapering, was abnormally dispersed along the stereocilia shafts in Tprn-null mice."
    explanation: >-
      Partner mislocalisation in the taperin null, the mirror image of the taperin
      mislocalisation seen in the CLIC5 null.
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Stereocilia that lack TPRN develop warped rootlets with gradual loss of TRIOBP-5 and ANKRD24 from mechanosensory rows starting postnatally."
    explanation: >-
      The two rootlet proteins that are lost and the postnatal timing, which is what makes
      this a maintenance rather than a developmental lesion.
- name: Progressive Stereocilia Retraction and Fusion
  description: >-
    Bundles that formed acceptably then deteriorate. Stereocilia are pruned and retract
    asynchronously, individual stereocilia are missing from the first and third rows, the
    outer hair cell V shape is distorted, and inner hair cell stereocilia fuse. Scanning
    electron microscopy in one knockout line traces the inner hair cell course from
    apparently normal at postnatal day 3 to scattered absence at day 15 and substantial loss
    by day 30; a second line reports outer hair cell degeneration from day 30. The two
    published lines disagree about which cell type leads, and both should be read as
    describing a progressive loss rather than a fixed pattern.
  biological_scale: CELLULAR
  cell_types:
  - preferred_term: cochlear inner hair cell
    term:
      id: CL:0000589
      label: cochlear inner hair cell
  - preferred_term: cochlear outer hair cell
    term:
      id: CL:0000601
      label: cochlear outer hair cell
  biological_processes:
  - preferred_term: auditory receptor cell stereocilium organization
    term:
      id: GO:0060088
      label: auditory receptor cell stereocilium organization
    modifier: DECREASED
  downstream:
  - target: Inner Hair Cell Synaptic and Vesicular Abnormality
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Progressive loss of mechanoelectrical transduction current as stereocilia are lost
  - target: Progressive Sensorineural Hearing Impairment
    causal_link_type: DIRECT
  evidence:
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We show that TPRN-deficient mice have progressive deafness characterized by gradual asynchronous retraction and fusion of outer and inner hair cell stereocilia, followed by synaptic abnormalities."
    explanation: >-
      The structural lesion and its ordering relative to the synaptic changes curated on the
      next node.
  - reference: PMID:27693694
    reference_title: "Progressive hearing loss and degeneration of hair cell stereocilia in taperin gene knockout mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "scanning electronic microscopy revealed progressive degeneration of inner hair cell stereocilia, from apparently normal at postnatal days 3 (P3) to scattered absence at P15 and further to substantial loss at P30"
    explanation: >-
      The time course in the first published knockout, and the observation that bundles are
      normal to begin with.
  - reference: PMID:30159668
    reference_title: "Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We observed significant hearing loss and progressive degeneration of stereocilia in the outer hair cells of Tprn-null mice starting from postnatal day 30."
    explanation: >-
      The second line, which reports outer rather than inner hair cells leading and a later
      start. Cited beside the first so the disagreement is visible rather than averaged away.
- name: Inner Hair Cell Synaptic and Vesicular Abnormality
  description: >-
    A late change at the opposite pole of the cell from the lesion. Tprn-null inner hair
    cells accumulate clustered endosome-like vesicles below the nucleus and at postsynaptic
    sites, and acquire efferent contacts directly on the cell body - axosomatic endings that
    are normally present only transiently in immature inner hair cells and, in adults, only
    after cochlear damage or in mutants with no transduction current.

    Whether this is downstream of the bundle failure or a second job taperin does is not
    settled. The authors set out both possibilities: progressive loss of transduction
    current is known to produce exactly these synaptic changes, and taperin separately
    carries an NPF motif, three predicted YXXphi motifs and a PP1 docking site, all of which
    point at endocytosis and vesicular trafficking. The edge into this node is therefore
    curated as indirect, and the alternative is recorded as a knowledge gap rather than
    being resolved here.
  biological_scale: CELLULAR
  cell_types:
  - preferred_term: cochlear inner hair cell
    term:
      id: CL:0000589
      label: cochlear inner hair cell
  downstream:
  - target: Progressive Sensorineural Hearing Impairment
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Impaired afferent signalling from inner hair cells with disturbed vesicular traffic
  evidence:
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "TEM analyses of P30 Tprn−/− IHCs show numerous membranous vesicles clustered mostly in the cytoplasm below nuclei"
    explanation: The vesicular accumulation and the age at which it is seen.
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In adult mice, these axosomatic IHC contacts from efferent fibers were reported only after damage to the cochlea, in aging mice, or in mutants with no MET currents"
    explanation: >-
      What makes the efferent finding informative: in an adult it is a marker of cochlear
      damage or of absent transduction, which is why the edge into this node is drawn as
      indirect rather than as a separate primary lesion.
phenotypes:
- name: Progressive Sensorineural Hearing Impairment
  category: Auditory
  description: >-
    Bilateral sensorineural hearing loss whose course differs between families carrying the
    same null allele. The Dutch family carrying c.1347delG has rapidly progressive loss; one
    Pakistani family homozygous for c.42_52del11 progressed from moderate at ages 7 to 9 to
    moderate-to-profound by 13 to 17, with the high frequencies deteriorating faster than
    the low ones; a Moroccan family with the identical allele had severe loss that was
    stable into the third decade. Progression should therefore be expected but cannot be
    predicted from the genotype.

    Bound to HP:0008619 rather than HP:0001730 so the record carries laterality as well as
    course: the loss is bilateral in every reported family, and `clinical_course: PROGRESSIVE`
    supplies the progression the plainer term would otherwise have to carry alone. Severity is
    deliberately not set here, because it is the moving quantity - the point of the record is
    that where a given family ends up is not predictable.
  phenotype_term:
    preferred_term: Progressive bilateral sensorineural hearing impairment
    term:
      id: HP:0008619
      label: Bilateral sensorineural hearing impairment
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:20170898
    reference_title: "Mutations in TPRN cause a progressive form of autosomal-recessive nonsyndromic hearing loss."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified another family with progressive ARNSHL linked to this locus, whose affected members were shown to carry a causative 1 bp deletion (c.1347delG) in exon 1 of TPRN."
    explanation: The family in which progression was first documented, and its allele.
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The current audiograms of the two affected individuals revealed moderate to profound hearing loss"
    explanation: >-
      The audiometric endpoint in the progressive Pakistani family, against the moderate
      loss the same two children had at school entry.
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is interesting to note that the loss in hearing is quite similar at low frequencies, and dramatic shifts of 20-30 dB are observed between the siblings at frequencies of 2-4 KHz."
    explanation: >-
      The frequency asymmetry of the progression, high frequencies moving faster, which
      matches the mouse course.
- name: Prelingual Severe to Profound Hearing Impairment
  category: Auditory
  description: >-
    The presentation in the founding Pakistani pedigree and in the Moroccan family: hearing
    loss present before speech acquisition, severe to profound, and in the Moroccan family
    stable rather than deteriorating. This is the other pole of the same disease, and it is
    the reason DFNB79 cannot be summarised as a purely postlingual progressive entity.
    `severity: SEVERE` follows the reported audiometric range in these families, severe to
    profound; some individuals reach the profound end and the enum has no value spanning
    both.
  phenotype_term:
    preferred_term: Prelingual sensorineural hearing impairment
    term:
      id: HP:0000399
      label: Prelingual sensorineural hearing impairment
    severity: SEVERE
  evidence:
  - reference: PMID:19603065
    reference_title: "DFNB79: reincarnation of a nonsyndromic deafness locus on chromosome 9q34.3."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genetic analysis of an inbred Pakistani family PKDF280, segregating prelingual severe to profound sensorineural hearing loss, provided evidence for a DFNB locus on human chromosome 9q34.3."
    explanation: The phenotype of the pedigree the locus was named for.
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The same mutation was identified in members of a large Moroccan family suffering a severe degree of hearing loss, which is stable in the third decade of life"
    explanation: >-
      The stable severe presentation on the same allele that elsewhere progresses, which is
      why both phenotype records are curated rather than one.
- name: Normal Vestibular Function
  category: Vestibular
  frequency: EXCLUDED
  description: >-
    Balance is spared, and this is a positive finding rather than an absence of enquiry.
    Romberg and tandem gait testing were normal in the affected children of the progressive
    Pakistani family, and quantitative vestibular sensory evoked potentials in Tprn-null
    mice show no significant difference from wild-type littermates at postnatal day 30 or
    60, with no circling or head bobbing at any age.

    Recorded explicitly because the neighbouring taper-region disease behaves differently:
    DFNB103 (CLIC5) presents with vestibular areflexia in patients and florid circling in
    mice. Two proteins in the same rings, and only one of them is needed for vestibular hair
    cells.

    `frequency: EXCLUDED` carries the absence, because that is what the HPOA exporter reads
    to emit a NOT-qualified row; `modifier: ABSENT` alone documents intent and is not
    consulted. Neither slot is a prevalence claim, and none is made here - three children
    with bedside tests is not a denominator, and the mouse data cannot supply one for
    humans.
  phenotype_term:
    preferred_term: Normal vestibular function
    term:
      id: HP:0001751
      label: Abnormal vestibular function
    modifier: ABSENT
  evidence:
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Tandem walking was normal, and the Romberg test was also negative among affected children, suggesting normal vestibular function."
    explanation: >-
      The only formal human vestibular assessment in a reported DFNB79 family, and its
      result.
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    directness: INDIRECT
    snippet: "Thus, TPRN is necessary for auditory hair cell function and, at least in the first few months of life, is not necessary for vestibular hair cell function."
    explanation: >-
      The mouse counterpart, quantitative rather than bedside. Indirect with respect to the
      human claim because it is a different species, and the authors themselves limit it to
      the first few months of life.
genetic:
- name: TPRN
  notes: >-
    TPRN, previously C9orf75, lies at 9q34.3 and encodes taperin, a vertebrate-specific
    protein named for where it sits rather than for what it does. Its N-terminal region
    cross-links F-actin; a C-terminal region carries a nuclear localisation signal, and the
    protein docks the alpha isoform of protein phosphatase 1 through a classic RVxF motif,
    suppressing the phosphatase's general activity. Steady-state localisation in
    non-sensory cells is predominantly nuclear, and taperin is recruited to sites of DNA
    damage in complex with Ku70, Ku80, PARP and topoisomerases. None of that nuclear biology
    has been connected to deafness, and it is recorded here because it is the reason a
    taperin-directed therapy cannot be assumed to be inner-ear-specific.

    Taperin shares an ancestral relationship with phostensin, a cytosolic actin-binding PP1
    partner, which was the basis for the original guess - made when the gene was found and
    before any activity was measured - that it would turn out to have a role in actin
    dynamics.

    Penetrance has not been formally estimated. Every reported homozygote in every family is
    affected and no unaffected homozygote has been described - but the pedigrees were
    ascertained through deafness, which is the ascertainment that makes complete penetrance
    look inevitable whether or not it is. Heterozygotes are consistently unaffected, in
    families and in mice.

    Dosage runs in both directions. Overexpressing taperin in wild-type hair cells causes
    excessive actin bundling, extra stereocilia rows, over-elongation and degeneration, and
    reducing taperin expression rescues the stereocilia defects and partially restores
    hearing in Grxcr2-null mice, whose primary lesion is failure to keep taperin restricted
    to the stereocilia base. Taperin is therefore a protein whose level, not merely whose
    presence, is the phenotype-determining variable.
  relationship_type: CAUSATIVE
  gene_term:
    preferred_term: TPRN
    term:
      id: hgnc:26894
      label: TPRN
  evidence:
  - reference: PMID:20170899
    reference_title: "Targeted capture and next-generation sequencing identifies C9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness DFNB79."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although TPRN is expressed in many tissues, immunolocalization of the protein product in the mouse cochlea shows prominent expression in the taper region of hair cell stereocilia. Consequently, we named the protein taperin."
    explanation: >-
      The localisation that gave the protein its name, and the observation that expression
      is not restricted to the ear.
  - reference: PMID:23213405
    reference_title: "Taperin (c9orf75), a mutated gene in nonsyndromic deafness, encodes a vertebrate specific, nuclear localized protein phosphatase one alpha (PP1alpha) docking protein."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Taperin associates with PP1 through a classic 'RVxF' motif and suppresses the general phosphatase activity of the enzyme."
    explanation: >-
      The biochemical activity outside the ear, which is the basis for the caution about
      systemic effects of any taperin-directed intervention.
  - reference: PMID:23213405
    reference_title: "Taperin (c9orf75), a mutated gene in nonsyndromic deafness, encodes a vertebrate specific, nuclear localized protein phosphatase one alpha (PP1alpha) docking protein."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Taperin also shares an ancestral relationship with the cytosolic actin binding protein phostensin, another PP1 interacting partner."
    explanation: >-
      The homology that predicted the actin function years before it was demonstrated
      biochemically.
  - reference: PMID:35752427
    reference_title: "Reducing Taperin Expression Restores Hearing in Grxcr2 Mutant Mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    directness: INDIRECT
    snippet: "Functional analysis further confirmed that reducing taperin expression partially restored hearing in Grxcr2 null mice."
    explanation: >-
      Evidence that taperin level is itself a determinant of hearing. Indirect with respect
      to DFNB79, because the experiment lowers taperin in a different mutant background
      rather than testing a TPRN genotype.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    DFNB79 has been reported in a small number of families - four Pakistani pedigrees linked
    to the locus, a Moroccan family and a Dutch family in the founding reports, and single
    additional families since. No population prevalence estimate exists and no
    rate_per_100000 is recorded, because none has been published; ULTRA_RARE is the
    qualitative band rather than a numeric conversion.
  evidence:
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The DFNB79 locus harbors TPRN mutations in which have been reported in a few families with deafness."
    explanation: The size of the reported literature, in the authors' own words.
- population: Consanguineous Pakistani families and sporadic cases with moderate to severe hearing loss
  measure_type: UNKNOWN
  notes: >-
    A targeted screen of 50 consanguineous multiplex families and 57 sporadic cases from
    Pakistan found no further DFNB79-linked family and no case homozygous for markers
    spanning TPRN. That is a negative diagnostic yield in an ascertained cohort, not a
    population rate, so no prevalence_class or rate_per_100000 is recorded; putting a
    numeric band here would assert an occurrence estimate the study does not make. The
    ascertainment also selected for moderate-to-severe rather than progressive loss, which
    the authors identify as the limitation on what the negative result means.
  evidence:
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This suggests that TPRN is not a significant contributor to moderate to severe hearing loss in the Pakistani population, although its contribution to progressive hearing loss remains to be determined."
    explanation: >-
      The negative screen and the authors' own statement of what it does and does not
      exclude.
progression:
- phase: Onset
  age_range: prelingual to about 2 years
  notes: >-
    Onset is early. In the progressive Pakistani family the parents noticed the loss by age
    2; in the founding pedigree and the Moroccan family the loss was prelingual. A newborn
    hearing screen has not been reported as passed or failed in any DFNB79 family, so this
    entry does not state whether the disease is detectable at birth.
  evidence:
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "According to the parents, the onset of hearing loss was noticed by 2 years of age."
    explanation: The reported age of recognition in the family with the best-documented history.
- phase: Deterioration or stability
  age_range: childhood to third decade
  notes: >-
    Where the disease progresses it does so through childhood and adolescence, faster at
    high frequencies. Where it does not, the loss reported in the Moroccan family remained
    stable into the third decade. Which course a given family follows is not predictable
    from the TPRN allele, and serial audiometry is the only way to tell them apart.
  evidence:
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This suggests that hearing at high frequencies worsens rapidly, while loss of hearing at lower frequencies may be more gradual."
    explanation: The frequency-dependent shape of the progression where it occurs.
diagnosis:
- name: TPRN sequencing on recessive nonsyndromic hearing loss panels
  description: >-
    DFNB79 is reached by exome sequencing or a deafness panel containing TPRN, after GJB2
    has been excluded. Because every reported allele lies in exon 1, sequencing that exon
    alone was proposed as a cheap first pass in recessive nonsyndromic hearing loss,
    particularly where there are signs of progression. Vestibular testing does not
    discriminate - it is normal in DFNB79 - so a progressive recessive loss with normal
    balance is the clinical shape that should prompt the test, and vestibular involvement
    argues for a different taper-region gene.
  evidence:
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sequencing of this exon may be considered in recessively inherited cases of nonsyndromic hearing loss, especially if signs of progression are present"
    explanation: The explicit testing recommendation and the clinical trigger for it.
treatments:
- name: Genetic Counselling with Serial Audiometry
  description: >-
    Counselling for a recessive condition with a 25 percent sibling recurrence risk, and
    repeated rather than single audiometric assessment. Serial testing is the substantive
    part: the same TPRN allele produces a stable loss in one family and a progressive one in
    another, so a single audiogram establishes the current threshold and nothing about the
    trajectory. Where progression occurs it is faster at high frequencies, which is where
    the follow-up should be looking.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thus the same mutation of TPRN can be associated with different thresholds of hearing as well as differences in the stability of the phenotype."
    explanation: >-
      The reason a single assessment is insufficient: the genotype does not fix either the
      threshold or the trajectory.
  notes: >-
    No target_mechanisms link is recorded on this treatment. Counselling and surveillance do
    not act on a pathograph node at all, and no TreatmentEffectEnum value describes them -
    INHIBITS, ACTIVATES, MODULATES, BYPASSES and RESTORES are all claims about changing a
    mechanism, and measuring one is none of those. Asserting the least-wrong value would put
    a false mechanistic claim in a machine-readable slot; the two device treatments below
    carry the section's join points into the graph instead.

    AAV gene replacement is not curated as a treatment: the work is preclinical and is
    recorded under animal_models, where the dosage constraint can be stated beside it.
- name: Cochlear Implantation
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: cochlear device implantation
    term:
      id: NCIT:C15329
      label: Surgical Procedure
    qualifiers:
    - predicate:
        preferred_term: medical device
        term:
          id: NCIT:C16830
          label: Medical Device
      value:
        preferred_term: cochlear implant
        term:
          id: NCIT:C157820
          label: Cochlear Implant
  description: >-
    The standard intervention for severe-to-profound sensorineural hearing loss, and the
    mechanism here argues for it directly. The DFNB79 lesion is inside the hair cell
    stereocilium: the bundle fails, and the hair cell can no longer convert sound into a
    receptor potential. An implant stimulates the spiral ganglion electrically and does not
    need a working bundle, so it operates downstream of everything this entry's pathograph
    describes.

    One caveat belongs beside that argument rather than after it. Tprn-null mice develop
    inner hair cell synaptic and vesicular abnormalities and acquire efferent contacts on the
    cell body, and the same study raises the possibility of a direct role for taperin in
    vesicular trafficking rather than a purely secondary consequence of losing transduction.
    If that turns out to be true in patients, the neural side of the pathway is not entirely
    spared and implant outcome would be less predictable than the bundle-lesion argument
    implies. Nobody has looked.
  target_mechanisms:
  - target: Progressive Stereocilia Retraction and Fusion
    treatment_effect: BYPASSES
    description: >-
      Electrical stimulation of the spiral ganglion substitutes for the transduction current
      a fused or retracted bundle can no longer generate, so the implant works downstream of
      the node that fails.
  notes: >-
    Carries no evidence item deliberately. No DFNB79 patient has a reported implantation
    outcome - the published literature is a handful of families, and the one report that
    mentions devices at all says none of the affected children wore hearing aids. The
    mechanistic argument above is this entry's inference from the site of the lesion and is
    labelled as such; quoting the general cochlear-implant literature here would attach
    evidence about a different population to a claim about this disease. Follows the pattern
    used in Autosomal_Recessive_Nonsyndromic_Hearing_Loss_97.
- name: Hearing Amplification
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: hearing aid amplification
    term:
      id: NCIT:C15315
      label: Rehabilitation
    qualifiers:
    - predicate:
        preferred_term: medical device
        term:
          id: NCIT:C16830
          label: Medical Device
      value:
        preferred_term: hearing aid
        term:
          id: NCIT:C183182
          label: Hearing Aid
  description: >-
    Amplification is the first-line intervention while useful residual hearing remains, which
    in DFNB79 is most of childhood in the families whose loss begins mild or moderate. Unlike
    an implant it does not bypass the lesion - it raises the stimulus reaching a bundle that
    still partly works - so its useful life is bounded by how fast the loss progresses, and
    that rate is not predictable from the genotype.
  target_mechanisms:
  - target: Progressive Sensorineural Hearing Impairment
    description: >-
      Compensates for the threshold loss by raising the sound pressure reaching a bundle that
      is degenerating but not yet lost. It does not act on the taper defect or slow the
      stereocilia degeneration driving it, which is why no treatment_effect value is
      recorded - the enum's values all assert a change to the mechanism, and amplification
      makes no such claim.
  notes: >-
    Carries no evidence item deliberately, for the same reason as the implantation record. The
    only DFNB79 report that mentions devices states that none of the affected individuals in
    that family wore hearing aids, which is a description of what happened in one Pakistani
    village rather than evidence about efficacy, and it is not quoted here as though it were
    either.
animal_models:
- name: Tprn TALEN knockout mouse
  species: Mouse
  genotype: Tprn -/-, 11 bp deletion at nucleotides 177-187 of exon 1
  publication: PMID:27693694
  description: >-
    The first taperin knockout, made with TALENs and carrying an 11 bp exon 1 deletion of
    the same class as the human founding allele. Homozygotes have progressive sensorineural
    hearing loss on click and tone-burst auditory brainstem response at postnatal days 15,
    30 and 60; heterozygotes are indistinguishable from wild type, which matches the
    recessive human inheritance. Hair cell counts are preserved on phalloidin labelling
    while the stereocilia themselves degenerate, so the model separates bundle failure from
    cell death.
  genes:
  - preferred_term: TPRN
    term:
      id: hgnc:26894
      label: TPRN
  modeled_mechanisms:
  - target: Progressive Stereocilia Retraction and Fusion
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      The structural lesion, from a normal starting point. Bundles are unremarkable at
      postnatal day 3 and then deteriorate, which is the sequence the human progressive
      phenotype implies but which no patient material shows.
    limitations: >-
      The mouse course runs over weeks where the human one runs over years, and this line
      reports inner hair cell stereocilia leading with outer hair cells much less severely
      affected, which is the opposite emphasis to the CRISPR null line. The disagreement is
      unresolved, so neither line should be treated as fixing which cell type fails first in
      patients. The allele is a protein-null; whether human truncating alleles in exon 1
      behave identically has not been shown at the protein level in patients.
    readouts:
    - name: Inner hair cell stereocilia by scanning electron microscopy
      target: Progressive Stereocilia Retraction and Fusion
      direction: DECREASED
      interpretation: >-
        Stereocilia are progressively lost from normal-appearing bundles between postnatal
        days 3 and 30.
      evidence:
      - reference: PMID:27693694
        reference_title: "Progressive hearing loss and degeneration of hair cell stereocilia in taperin gene knockout mice."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "scanning electronic microscopy revealed progressive degeneration of inner hair cell stereocilia, from apparently normal at postnatal days 3 (P3) to scattered absence at P15 and further to substantial loss at P30"
        explanation: The structural measurement and its time course.
    - name: Auditory brainstem response threshold
      target: Progressive Stereocilia Retraction and Fusion
      direction: INCREASED
      interpretation: >-
        Thresholds rise across postnatal days 15, 30 and 60 - hearing gets worse, so the
        threshold value goes up.
      evidence:
      - reference: PMID:27693694
        reference_title: "Progressive hearing loss and degeneration of hair cell stereocilia in taperin gene knockout mice."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Homozygous TPRN-/- mice exhibited progressive sensorineural hearing loss as reflected by auditory brainstem response to both click and tone burst stimuli at postnatal days 15 (P15), 30 (P30), and 60 (P60)."
        explanation: The functional measurement behind this readout and the ages tested.
    evidence:
    - reference: PMID:27693694
      reference_title: "Progressive hearing loss and degeneration of hair cell stereocilia in taperin gene knockout mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Heterozygous TPRN+/- mice showed apparently normal auditory phenotypes to their wide-type (WT) littermates."
      explanation: >-
        The recessive behaviour of the mouse allele, which is what makes the line
        informative for a recessive human disease rather than for a dominant one.
- name: Tprn CRISPR-null mouse on CBA/CaJ
  species: Mouse
  genotype: Tprn-null, CRISPR/Cas9-generated, CBA/CaJ background
  publication: PMID:30159668
  description: >-
    An independent null on a background without the age-related hearing loss confounder that
    complicates other strains. This is the line in which the rootlet lesion was described:
    curved rootlet shafts, hollow central cores with loose peripheral dense rings, dispersal
    of radixin along the stereocilia shafts, and reduced radixin and beta-actin levels.
    Outer hair cell stereocilia degenerate from postnatal day 30.
  genes:
  - preferred_term: TPRN
    term:
      id: hgnc:26894
      label: TPRN
  modeled_mechanisms:
  - target: Stereociliary Rootlet Destabilization
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Where the rootlet claim comes from. Rootlet ultrastructure cannot be examined in
      living patients, so this is not corroboration of a human finding; it is the experiment
      in which the lesion was defined.
    limitations: >-
      The rootlet abnormalities were described qualitatively from transmission electron
      micrographs rather than quantified, and the radixin and beta-actin reductions are
      whole-cochlea measurements that cannot localise the loss to the taper. The line
      reports outer hair cells degenerating first, which the TALEN line does not.
    readouts:
    - name: Rootlet ultrastructure by transmission electron microscopy
      target: Stereociliary Rootlet Destabilization
      direction: ALTERED
      interpretation: >-
        Rootlets are present but malformed - curved shafts, hollow cores, loose peripheral
        rings - so the defect is in maintaining the structure rather than in building it.
      evidence:
      - reference: PMID:30159668
        reference_title: "Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Transmission electron microscopy images of stereociliary bundles in the mutant mice showed some stereociliary rootlets with curved shafts. The central cores of the stereociliary rootlets possessed hollow structures with surrounding loose peripheral dense rings."
        explanation: The ultrastructural measurement behind this readout.
    - name: Radixin distribution along stereocilia
      target: Stereociliary Rootlet Destabilization
      direction: ALTERED
      interpretation: >-
        Radixin leaves the taper and spreads along the shaft, which is the partner-protein
        signature of a failed taper complex.
      evidence:
      - reference: PMID:30159668
        reference_title: "Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Radixin, a protein expressed at stereocilia tapering, was abnormally dispersed along the stereocilia shafts in Tprn-null mice."
        explanation: The immunolocalisation measurement behind this readout.
    evidence:
    - reference: PMID:30159668
      reference_title: "Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "The generated Tprn-null mice are ideal models of human hereditary deafness DFNB79."
      explanation: >-
        The authors' own claim for the line's relevance. Recorded as their assessment rather
        than endorsed - the limitations above are the reasons this entry does not repeat the
        word "ideal".
- name: Tprn knockout mouse treated with AAV-Tprn
  species: Mouse
  genotype: Tprn knockout treated with promoter-driven recombinant AAV carrying Tprn
  publication: PMID:37952086
  description: >-
    A gene-replacement experiment whose result cuts two ways. Delivering Tprn by AAV at an
    appropriate level restores the concentric rings at the taper and repairs hearing in Tprn
    knockout mice. In the same study, overexpressing taperin is one of the two manipulations
    used to break the rings deliberately - the other being competitive inhibition of the
    taperin-CLIC5 interaction - and it produces stereocilia degeneration and severe hearing
    loss on its own.
  genes:
  - preferred_term: TPRN
    term:
      id: hgnc:26894
      label: TPRN
  modeled_mechanisms:
  - target: Loss of F-Actin Bundling at the Stereocilia Taper
    relationship: RESCUES
    fidelity: MODERATE
    description: >-
      The forward test of the mechanism: restoring the protein restores the structure and
      the function. That is a stronger argument for the ring being the operative unit than
      any correlation between its absence and the phenotype.
    limitations: >-
      Rescue is conditional on dose. The same paper uses taperin overexpression as a tool to
      destroy the rings, so the therapeutic window is bounded above as well as below, and no
      dose-response curve mapping that window has been published. The experiment is also a
      mouse cochlea injected under laboratory conditions; nothing here addresses the age at
      which a patient with an already-degenerated bundle could be treated, and the human
      onset is prelingual or early childhood in every reported family.
    readouts:
    - name: Auditory function after AAV-Tprn delivery
      target: Loss of F-Actin Bundling at the Stereocilia Taper
      direction: RESTORED
      interpretation: >-
        Hearing is repaired when the rings are restored, tying the auditory outcome to the
        structure rather than to the presence of the protein anywhere in the cell.
      evidence:
      - reference: PMID:37952086
        reference_title: "Critical role of TPRN rings in the stereocilia for hearing."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "restoration of the TPRN rings can rescue the damaged auditory function of Tprn knockout mice by exogenously expressing TPRN at an appropriate level in HCs via promoter recombinant adeno-associated virus (AAV)"
        explanation: >-
          The rescue measurement, including the authors' own qualifier "at an appropriate
          level", which is the dosage constraint this model is curated to record.
    evidence:
    - reference: PMID:37952086
      reference_title: "Critical role of TPRN rings in the stereocilia for hearing."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "TPRN ring restoration in stereocilia by AAV-Tprn effectively repairs damaged hearing, which lays the foundation for the clinical application of AAV-mediated gene therapy in patients with TPRN mutation."
      explanation: >-
        The authors' statement of translational intent, recorded as their claim. The
        overexpression toxicity documented in the same study is why this entry treats it as
        a foundation rather than a plan.
discussions:
- discussion_id: tprn_dosage_window_for_gene_replacement
  kind: HUMAN_MODEL_MISMATCH
  prompt: >-
    AAV delivery of Tprn repairs hearing in taperin-null mice, but taperin overexpression is
    itself used as a tool to destroy the stereocilia rings and causes deafness. Is there a
    dose of taperin that is therapeutic in a human cochlea, and how would anyone know they
    were inside it?
  attaches_to:
  - animal_models#Tprn knockout mouse treated with AAV-Tprn
  - pathophysiology#Loss of F-Actin Bundling at the Stereocilia Taper
  - genetic#TPRN
  rationale: >-
    Most recessive loss-of-function diseases have a one-sided dosage problem: more protein
    is better up to normal, and the engineering question is how to deliver enough. Taperin
    is not like that. In the same study that reports the AAV rescue, exogenous taperin
    overexpression is one of the two deliberate methods used to disrupt the rings, and it
    produces stereocilia degeneration and severe hearing loss. An independent group reports
    the same in wild-type hair cells: excessive F-actin bundling, extra rows, over-elongated
    and degenerating stereocilia. And from the opposite direction, lowering taperin rescues
    a different mutant - Grxcr2-null mice, whose lesion is failure to keep taperin confined
    to the base - which is only coherent if the pathogenic quantity is taperin activity in
    the wrong place or the wrong amount rather than its absence.

    The rescue was reported as expression "at an appropriate level", which is the honest
    description of an experiment in which the level was achievable and not of one in which
    the window was measured. No dose-response curve bounding it has been published, and AAV
    transduction of a cochlea is not uniform: the same injection gives different copy
    numbers in different cells along the cochlear duct, so a dose that is therapeutic at the
    apex may be toxic at the base. In a disease where too much protein is a known cause of
    the same lesion, that heterogeneity is not a delivery inconvenience, it is the safety
    question.

    Two further mismatches sit underneath. Human onset is prelingual or by about age 2 in
    every reported family, so a patient's bundles have already deteriorated before a
    diagnosis exists, while the mouse experiments target a cochlea that is still developing.
    And taperin is expressed in many tissues and is a nuclear PP1-docking protein recruited
    to sites of DNA damage; a systemically delivered vector raises questions the cochlear
    experiments do not address.
  evidence:
  - reference: PMID:37952086
    reference_title: "Critical role of TPRN rings in the stereocilia for hearing."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The disruption of TPRN rings, triggered by the competitive inhibition of the interaction of TPRN and CLIC5 or exogenous TPRN overexpression, leads to stereocilia degeneration and severe hearing loss."
    explanation: >-
      Overexpression used as a method of causing the disease phenotype, in the same paper
      that reports the rescue.
  - reference: PMID:37952086
    reference_title: "Critical role of TPRN rings in the stereocilia for hearing."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "restoration of the TPRN rings can rescue the damaged auditory function of Tprn knockout mice by exogenously expressing TPRN at an appropriate level in HCs via promoter recombinant adeno-associated virus (AAV)"
    explanation: >-
      The rescue, with the dosage qualifier the authors attach to it and no published bound
      on what "appropriate" means.
  - reference: PMID:40471101
    reference_title: "Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In contrast, TPRN overexpression causes excessive F-actin bundling, extra rows, and over-elongation of stereocilia during development."
    explanation: >-
      Independent replication of the overexpression toxicity, in a different laboratory and
      with a different construct.
  - reference: PMID:35752427
    reference_title: "Reducing Taperin Expression Restores Hearing in Grxcr2 Mutant Mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    directness: INDIRECT
    snippet: "Reducing the expression of taperin, a protein that interacts with GRXCR2 at the base of stereocilia, corrects the morphological defects of stereocilia and restores hearing in Grxcr2 null mice."
    explanation: >-
      The other end of the dosage argument: lowering taperin is therapeutic in a different
      genotype. Indirect with respect to DFNB79 because the background is a Grxcr2 null, not
      a TPRN one.
  proposed_experiments:
  - experiment_id: exp_dfnb79_aav_tprn_dose_response
    name: Dose-response and cochlear-position mapping of AAV-Tprn rescue
    description: >-
      Deliver AAV-Tprn to Tprn-null mice across at least five vector doses spanning two
      orders of magnitude, and at two ages - one before and one after the stereocilia lesion
      is established - with auditory brainstem response and distortion product otoacoustic
      emissions as function, scanning electron microscopy of bundle morphology, and
      single-cell quantification of taperin immunofluorescence and vector genome copy number
      at apical, middle and basal positions. Include wild-type animals at the top doses to
      separate overexpression toxicity from incomplete rescue of the null.
    would_support:
    - pathophysiology#Loss of F-Actin Bundling at the Stereocilia Taper
    supporting_outcome:
    - >-
      A reproducible dose band exists in which hearing is restored at every cochlear
      position without inducing the over-elongation phenotype, and per-cell taperin levels
      inside that band cluster around the wild-type level, which would make an expression
      target rather than a vector dose the thing a clinical protocol has to hit.
    would_refute:
    - pathophysiology#Loss of F-Actin Bundling at the Stereocilia Taper
    refuting_outcome:
    - >-
      No dose rescues the base without over-elongating the apex, because the per-cell
      expression distribution from a single injection is wider than the therapeutic window,
      which would mean unregulated AAV replacement is the wrong modality for this gene
      regardless of vector improvements.
- discussion_id: tprn_identical_allele_discordant_progression
  kind: KNOWLEDGE_GAP
  prompt: >-
    The same c.42_52del11 null allele produces stable severe hearing loss into the third
    decade in one family and progressive loss in another. What determines whether DFNB79
    progresses?
  attaches_to:
  - phenotypes#Progressive Sensorineural Hearing Impairment
  - phenotypes#Prelingual Severe to Profound Hearing Impairment
  - genetic#TPRN
  rationale: >-
    This is not the ordinary observation that a rare disease is clinically variable. The
    allele is the same 11 bp deletion in exon 1, it is homozygous in both settings, and it
    is almost certainly a complete null - so the usual explanation for variable expressivity
    in a recessive disease, residual protein differing between genotypes, is unavailable
    here. The authors who found the discordance said so plainly and proposed a genetic
    modifier.

    Nobody has looked for it. In the fifteen years since, DFNB79 has been reported in only a
    handful of families, and no study has assembled enough homozygotes for the same allele
    to run a modifier search. That is a real obstacle rather than an oversight: modifier
    mapping needs numbers this disease does not have in any single population.

    The question is worth keeping open because the answer would be actionable in a way the
    diagnosis currently is not. A family told that their child is homozygous for
    c.42_52del11 cannot be told whether the loss will stay where it is or progress to
    profound, which is exactly the information that determines when to consider
    implantation and how often to re-test. It also bears on the mechanism: something that
    modifies the rate of a rootlet-maintenance failure is a candidate for the same
    protective role in commoner acquired progressive hearing loss.

    The obvious first candidates are the other taper-region proteins the pathophysiology
    section already names - CLIC5, PTPRQ, TRIOBP, ANKRD24, GRXCR2 - since taperin's function
    is defined by that complex and GRXCR2 dosage is already known to change what taperin
    does. Testing them requires only sequencing existing DFNB79 families, not new
    recruitment.
  evidence:
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In contrast to the previously reported individuals affected by the same mutation, hearing loss is likely to be progressive in this family."
    explanation: The discordance itself, on an identical genotype.
  - reference: PMID:23340767
    reference_title: "The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The c.42_52del11 is most likely to be a null mutation. Therefore, its involvement in progressive hearing loss in a family from Pakistan and in stable hearing loss phenotype in another Pakistani and a Moroccan family strongly suggests the presence of a genetic modifier."
    explanation: >-
      The authors' own reasoning, including the step this gap depends on: a null allele
      leaves no room for a residual-function explanation.
  - reference: PMID:30380417
    reference_title: "GRXCR2 Regulates Taperin Localization Critical for Stereocilia Morphology and Hearing."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    directness: INDIRECT
    snippet: "We show that taperin and GRXCR2 form a complex and that taperin is diffused throughout the stereocilia length in Grxcr2-deficient hair cells."
    explanation: >-
      Why GRXCR2 is a named candidate modifier rather than a generic suggestion: it already
      determines where taperin is. Indirect because no human DFNB79 family has been
      genotyped at GRXCR2.
  proposed_experiments:
  - experiment_id: exp_dfnb79_taper_complex_modifier_screen
    name: Targeted sequencing of taper-complex genes in discordant DFNB79 homozygotes
    description: >-
      Sequence CLIC5, PTPRQ, TRIOBP, ANKRD24, GRXCR2, RDX and MYO6 in all available
      individuals homozygous for TPRN c.42_52del11 from the Moroccan and both Pakistani
      families, together with serial audiograms defining each individual as progressive or
      stable, and test whether any variant or haplotype in these genes segregates with the
      progressive course across families rather than within one of them.
    would_support:
    - phenotypes#Progressive Sensorineural Hearing Impairment
    supporting_outcome:
    - >-
      A variant in one of the taper-complex genes tracks with progression across families
      carrying the same TPRN null, which would give the counselling answer and would
      identify the complex as the site of the rate-limiting step.
    would_refute:
    - phenotypes#Progressive Sensorineural Hearing Impairment
    refuting_outcome:
    - >-
      No taper-complex variant distinguishes progressive from stable individuals, which
      would move the search to genome-wide modifiers or to non-genetic determinants such as
      noise exposure history, and would mean the complex hypothesis had been tested rather
      than left as a plausible guess.
📚

References & Deep Research

References

15
PMID:20170899
Targeted capture and next-generation sequencing identifies C9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness DFNB79.
No top-level findings curated for this source.
PMID:20170898
Mutations in TPRN cause a progressive form of autosomal-recessive nonsyndromic hearing loss.
No top-level findings curated for this source.
PMID:19603065
DFNB79: reincarnation of a nonsyndromic deafness locus on chromosome 9q34.3.
No top-level findings curated for this source.
PMID:23340767
The c.42_52del11 mutation in TPRN and progressive hearing loss in a family from Pakistan.
No top-level findings curated for this source.
PMID:40471101
Taperin bundles F-actin at stereocilia pivot points enabling optimal lifelong mechanosensitivity.
No top-level findings curated for this source.
PMID:37952086
Critical role of TPRN rings in the stereocilia for hearing.
No top-level findings curated for this source.
PMID:30159668
Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice.
No top-level findings curated for this source.
PMID:27693694
Progressive hearing loss and degeneration of hair cell stereocilia in taperin gene knockout mice.
No top-level findings curated for this source.
PMID:24285636
CLIC5 stabilizes membrane-actin filament linkages at the base of hair cell stereocilia in a molecular complex with radixin, taperin, and myosin VI.
No top-level findings curated for this source.
PMID:30380417
GRXCR2 Regulates Taperin Localization Critical for Stereocilia Morphology and Hearing.
No top-level findings curated for this source.
PMID:35752427
Reducing Taperin Expression Restores Hearing in Grxcr2 Mutant Mice.
No top-level findings curated for this source.
PMID:23213405
Taperin (c9orf75), a mutated gene in nonsyndromic deafness, encodes a vertebrate specific, nuclear localized protein phosphatase one alpha (PP1alpha) docking protein.
No top-level findings curated for this source.
PMID:27269051
Murine Fam65b forms ring-like structures at the base of stereocilia critical for mechanosensory hair cell function.
No top-level findings curated for this source.
PMID:32631815
A RIPOR2 in-frame deletion is a frequent and highly penetrant cause of adult-onset hearing loss.
No top-level findings curated for this source.
PMID:34026762
N-Terminus of GRXCR2 Interacts With CLIC5 and Is Essential for Auditory Perception.
No top-level findings curated for this source.

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (1)

Create: Autosomal Recessive Nonsyndromic Hearing Loss 79 (DFNB79, TPRN) · 2026-09-01T18:05:47Z · View source

De novo curation of DFNB79 (MONDO:0013215), biallelic TPRN/taperin. entry_type decision: DISEASE. One gene, one conserved pathograph (TPRN loss -> loss of F-actin bundling at the stereocilia taper -> rootlet destabilisation -> progressive stereocilia retraction and fusion -> late IHC synaptic/vesicular abnormality -> progressive SNHL). Not a SUBTYPE: no existing dismech entry covers TPRN, and DFNB103/CLIC5 is a distinct gene with a distinct clinical picture. Not a GROUPING: no member diseases. Sources: own PubMed sweep (TPRN/DFNB79/taperin) plus an Edison/falcon deep-research report (research/Autosomal_Recessive_Nonsyndromic_Hearing_Loss_79-deep-research-falcon.md). NEC preflight PASS: TPRN mentioned 51 times, OMIM 613307 agreed between MONDO and report. Two DR-suggested HPO terms were rejected on lookup rather than adopted (HP:0012717 resolves to 'Severe conductive hearing impairment', not 'prelingual hearing loss' as the report claimed); every term in the entry was resolved through OLS before use. Agreement with the CLIC5 entry (DFNB103): both are curated around the same taper-region complex and cite the same PMID:24285636 observation, so the two entries rest on one shared claim rather than two independent assertions. The entries deliberately differ on vestibular involvement: CLIC5 loss gives vestibular areflexia in patients and circling in mice, whereas TPRN loss spares balance in both (normal Romberg/tandem gait in the one family formally tested; no significant VsEP difference in Tprn-null mice to P60). That negative is curated as a phenotype with frequency: EXCLUDED, following the ADLD precedent, because modifier: ABSENT alone is not read by the HPOA exporter. Two discussions: a HUMAN_MODEL_MISMATCH on the two-sided TPRN dosage window (AAV-Tprn rescues nulls, but taperin overexpression is used in the same paper as a method of destroying the rings, and lowering taperin rescues Grxcr2 nulls); and a KNOWLEDGE_GAP on identical c.42_52del11 homozygotes showing stable versus progressive loss, where a null allele leaves no residual-function explanation. Deliberately not curated: hearing aids and cochlear implantation (no DFNB79-specific outcome data); AAV gene replacement as a treatment (preclinical, recorded under animal_models with its dosage limitation); the nuclear PP1-docking and DNA-damage biology of taperin as a pathophysiology node (no link to deafness established, recorded in genetic notes). Validation: just validate exit 0 with 50/50 snippets verified; check-duplicate-keys, check-entity-refs, check-snippet-length, check-title-snippets, check-snippet-grading, check-environmental-evidence, check-folded-hyphens all exit 0.

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Disease Characteristics Research Template
Edison Scientific Literature 30 citations 2026-09-01T10:15:51.359904

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

  • Disease Name: Autosomal Recessive Nonsyndromic Hearing Loss 79 (DFNB79, TPRN-related)
  • MONDO ID: (if available)
  • Category: Mendelian

Research Objectives

Please provide a comprehensive research report on Autosomal Recessive Nonsyndromic Hearing Loss 79 (DFNB79, TPRN-related) covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

  • What is the disease? Provide a concise overview.
  • What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
  • What are the common synonyms and alternative names?
  • Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

  • Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
  • Risk Factors:

    Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases

  • Genetic risk factors (causal variants, susceptibility loci, modifier genes)
  • Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
  • Protective Factors:

    Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases

  • Genetic protective factors (protective variants, modifier alleles)
  • Environmental protective factors (diet, lifestyle, exposures that reduce risk)
  • Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

    Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

  • Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

    Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene

  • Pathogenic Variants:
  • Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
  • Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
  • Variant type/class (missense, frameshift, nonsense, splice-site, structural)
  • Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
  • Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
  • Functional consequences (loss of function, gain of function, dominant negative)
  • Modifier Genes: Genes that modify disease severity or expression
  • Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

    Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

  • Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

    Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases

  • Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

    Search first: CDC databases, WHO, PubMed, NHANES

  • Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

    Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

Present this section as an ordered causal chain first, then the detail below. Open with a numbered sequence of mechanistic steps running from the initiating lesion (mutation, exposure, infection) to the clinical manifestation, one step per line, each naming what it causes next. State the causal verb explicitly ("leads to", "results in") and say where a step is inferred rather than demonstrated. Where the mechanism branches, show the branch. The categories below are a checklist of what to cover within those steps, not the organizing structure — a step may draw on several of them, and a category may contribute to several steps.

  • Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

    Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc

  • Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

    Search first: Gene Ontology (GO), Reactome, KEGG, PubMed

  • Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

    Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold

  • Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

    Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA

  • Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

    Search first: ImmPort, Immunome Database, IEDB, Gene Ontology

  • Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

    Search first: PubMed, Gene Ontology, Reactome

  • Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

    Search first: BRENDA, UniProt, KEGG, OMIM, PubMed

  • Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Molecular Profiling (if available):
  • Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
  • Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
  • Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
  • Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
  • Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
  • Advanced Technologies (if applicable):
  • Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
  • Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
  • Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
  • Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

  • Organ Level:
  • Primary organs directly affected
  • Secondary organ involvement (complications, secondary effects)
  • Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

    Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT

  • Tissue and Cell Level:
  • Specific tissue types affected (epithelial, connective, muscle, nervous)
  • Specific cell populations targeted (with Cell Ontology terms)

    Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB

  • Subcellular Level:
  • Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

    Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas

  • Localization:
  • Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
  • Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

  • Onset:
  • Typical age of onset (congenital, pediatric, adult, geriatric)
  • Onset pattern (acute, subacute, chronic, insidious)

    Search first: OMIM, Orphanet, HPO, PubMed

  • Progression:
  • Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
  • Progression rate (rapid, slow, variable)
  • Disease course pattern (episodic, relapsing-remitting, progressive, stable)
  • Disease duration (self-limited, chronic lifelong)

    Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM

  • Patterns:
  • Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
  • Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

  • Epidemiology:
  • Prevalence (cases per 100,000 at given time)
  • Incidence (new cases per 100,000 per year)

    Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries

  • For Genetic Etiology:
  • Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
  • Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
  • Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
  • Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
  • Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
  • Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
  • Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
  • Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
  • Population Demographics:
  • Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
  • Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
  • Geographic distribution of specific variants
  • Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
  • Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

  • Clinical Tests:
  • Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
  • Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
  • Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
  • Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
  • Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
  • Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
  • Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
  • Genetic Testing:

    Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen

  • Overview of recommended genetic testing approach
  • Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
  • Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
  • Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
  • Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
  • Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
  • Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
  • FISH > Search first: ClinVar, cytogenetics databases, PubMed
  • Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
  • Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
  • Omics-Based Diagnostics (if applicable):
  • RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
  • Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
  • Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
  • Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
  • Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
  • Clinical Criteria:
  • Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
  • Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
  • Screening:
  • Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

  • Survival and Mortality:
  • Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
  • Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
  • Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
  • Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
  • Morbidity and Function:
  • Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
  • Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
  • Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
  • Disease Course:
  • Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
  • Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
  • Prediction:
  • Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
  • Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

  • Pharmacotherapy:
  • Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
  • Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
  • Advanced Therapeutics:
  • Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
  • Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
  • RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
  • Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
  • Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
  • Surgical and Interventional:
  • Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
  • Supportive and Rehabilitative:
  • Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
  • Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
  • Experimental:
  • Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
  • Treatment Outcomes:
  • Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
  • Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
  • Treatment Strategy:
  • Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
  • Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
  • Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest NCIT (NCI Thesaurus) clinical-intervention terms where applicable.

13. Prevention

  • Prevention Levels:
  • Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
  • Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
  • Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
  • Immunization: Vaccine strategies (if applicable)

    Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database

  • Screening and Early Detection:
  • Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
  • Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
  • Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
  • Behavioral Interventions: Lifestyle modifications to reduce risk

    Search first: CDC, WHO, behavioral intervention databases, Cochrane Library

  • Counseling: Genetic counseling (risk assessment, family planning guidance)

    Search first: NSGC resources, ACMG guidelines, GeneReviews

  • Public Health:
  • Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
  • Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
  • Prophylaxis: Preventive medications or procedures

    Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

  • Taxonomy: Species affected (with NCBI Taxon identifiers)

    Search first: NCBI Taxonomy

  • Breed: Specific breeds affected (with VBO identifiers if applicable)

    Search first: VBO (Vertebrate Breed Ontology)

  • Gene: Orthologous genes in other species (with NCBI Gene IDs)

    Search first: NCBI Gene

  • Natural Disease:
  • Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
  • Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
  • Comparative Biology:
  • Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
  • Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
  • Transmission (if applicable):
  • Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
  • Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

  • Model Types:
  • Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
  • Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
  • Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
  • Genetic Models:
  • Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
  • Model Characteristics:
  • Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
  • Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
  • Applications:
  • Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
  • Resources:
  • Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

  • Cite primary literature (PMID preferred) for all mechanistic and clinical claims
  • Prioritize recent reviews and landmark papers
  • Include direct quotes from abstracts where possible to support key statements
  • Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, NCIT, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (NCIT terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Autosomal Recessive Nonsyndromic Hearing Loss 79 (DFNB79; TPRN-related)

Executive summary

DFNB79 is an extremely rare Mendelian form of isolated sensorineural hearing loss caused by biallelic pathogenic variants in TPRN (formerly C9orf75), which encodes the stereociliary protein taperin. The strongest human evidence comes from consanguineous families with prelingual, bilateral, severe-to-profound hearing loss and no reported vestibular or extra-auditory manifestations. Experimental evidence places taperin at the taper/base of cochlear hair-cell stereocilia, where it participates in organization of the membrane–actin/rootlet apparatus. Loss or mislocalization of taperin disrupts stereocilia, ultimately causing hair-cell dysfunction or degeneration and hearing loss. There is no established DFNB79-specific prevalence, drug, gene therapy, biomarker, natural-history registry, or clinical trial. Current care therefore follows general management for genetic sensorineural hearing loss: early audiologic detection, molecular diagnosis, hearing aids where useful, cochlear-implant assessment for severe-to-profound loss, communication support, and genetic counseling.

Domain Best-supported finding Evidence type/strength Key source/date/DOI
Disease definition DFNB79 is an autosomal recessive, nonsyndromic deafness caused by biallelic truncating variants in TPRN (formerly C9orf75), encoding taperin. (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 1-3) Human discovery study; strong disease-gene evidence Rehman et al., Am J Hum Genet, Mar 2010, https://doi.org/10.1016/j.ajhg.2010.01.030
Inheritance Inheritance is autosomal recessive; original evidence came from multiple consanguineous Pakistani families linked to DFNB79. (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 1-3) Human pedigree/linkage + segregation; strong Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030
Gene/locus TPRN maps to chromosome 9q34.3; the DFNB79 critical interval analyzed was ~2.9 Mb. Mouse ortholog is syntenic to chromosome 2qA3. (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 6-7, rehman2010targetedcaptureand pages 1-3) Human mapping + comparative genomics; strong Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030
Hallmark phenotype Best-supported clinical phenotype is prelingual, bilateral, severe-to-profound sensorineural hearing loss with normal vestibular function and no syndromic features reported in the discovery families. (rehman2010targetedcaptureand pages 1-3) Human clinical phenotype from original families; moderate-strong Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030
Landmark variants Discovery variants were all truncating and located in exon 1: c.1056G>A (p.Trp352Ter/W352X), c.1244delC, c.44_54dup, and c.42_52del; absent in reported controls. (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 8-10) Human molecular genetics; strong Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030
Cellular site Taperin is concentrated at the taper/base region of hair-cell stereocilia in the cochlea. (rehman2010targetedcaptureand pages 8-10, rehman2010targetedcaptureand pages 1-3) Human-linked mouse localization data; strong for localization, indirect for human disease tissue Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030
Core mechanism Best-supported mechanism: loss of TPRN/taperin disrupts the stereociliary taper/rootlet membrane–actin complex; taperin interacts functionally with GRXCR2, CLIC5, radixin, MYO6, and PTPRQ, and mislocalization or loss causes stereocilia disorganization, hair-cell degeneration, and hearing loss. Direct human mechanistic proof remains limited. (liu2018grxcr2regulatestaperin pages 1-3, liu2018grxcr2regulatestaperin pages 10-12, li2021nterminusofgrxcr2 pages 8-9, rehman2010targetedcaptureand pages 8-10) Mouse/cellular mechanistic evidence; moderate for human inference Liu et al., Cell Reports, Oct 2018, https://doi.org/10.1016/j.celrep.2018.09.063; Salles et al., 2014 cited within gathered evidence
Epidemiology No DFNB79-specific prevalence/incidence estimate was identified in gathered evidence. Broader extrapolation: congenital hearing loss affects about 1–3 per 1,000 live births and a large fraction is genetic; AR forms predominate among nonsyndromic cases. (yun2024updatesongenetic pages 1-2, brotto2024autosomalrecessivenonsyndromic pages 1-2, lee2024clinicalgenetictesting pages 1-2) Broader hearing-loss reviews only; weak for DFNB79-specific epidemiology Yun & Lee, Apr 2024, 10.7874/jao.2024.00157; Brotto et al., Feb 2024, 10.3390/audiolres14020022; Lee et al., Jun 2024, 10.3390/biomedicines12071427
Diagnosis Disease-specific diagnosis is best supported by molecular testing of TPRN in the setting of congenital/prelingual ARNSHL. Broader extrapolation: contemporary practice favors hearing-loss gene panels first, with exome/genome/CNV analysis when panel testing is unrevealing. (rehman2010targetedcaptureand pages 5-6, yun2024updatesongenetic pages 1-2, lee2024clinicalgenetictesting pages 1-2, lee2024clinicalgenetictesting pages 9-11) Human disease-gene evidence + broader clinical practice reviews; moderate Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030; Lee et al., Jun 2024, 10.3390/biomedicines12071427
Treatment No TPRN-specific pharmacologic or gene-replacement treatment in humans was identified. Broader extrapolation: management of severe congenital genetic hearing loss currently relies on hearing aids and especially cochlear implantation when indicated. (brotto2024autosomalrecessivenonsyndromic pages 1-2, lee2024clinicalgenetictesting pages 1-2, lee2024clinicalgenetictesting pages 9-11) Broader hearing-loss management evidence; weak for TPRN-specific efficacy Brotto et al., Feb 2024, 10.3390/audiolres14020022; Lee et al., Jun 2024, 10.3390/biomedicines12071427
Trials No TPRN-specific clinical trial was identified in gathered evidence. Active hereditary hearing-loss gene-therapy trials currently target other genes, especially OTOF/DFNB9; these results should not be attributed to TPRN-related DFNB79. (duhon2024genetherapyadvancements pages 20-21, brotto2024autosomalrecessivenonsyndromic pages 3-5, lee2024clinicalgenetictesting pages 12-13) Clinical-trial/review evidence; strong for absence in gathered evidence, not proof of global absence Brotto et al., Feb 2024, 10.3390/audiolres14020022; Duhon et al., Jul 2024, 10.3389/fauot.2024.1423853
Evidence gaps Key gaps: no accessible second 2010 AJHG/2013 family full extraction in gathered evidence, limited DFNB79-specific natural-history and population-frequency data, sparse direct human mechanistic data, and inaccessible 2024 TPRN-ring paper during retrieval. (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 8-10, yun2024updatesongenetic pages 1-2, brotto2024autosomalrecessivenonsyndromic pages 3-5) Evidence-gap assessment; moderate Based on gathered evidence corpus through 2024

Table: This table condenses the highest-confidence findings for TPRN-related DFNB79, separating disease-specific evidence from broader hereditary hearing-loss extrapolation. It is useful for rapid knowledge-base population and for identifying where evidence remains sparse, especially treatment and trial data.

1. Disease information

Definition and identifiers

Preferred name: autosomal recessive nonsyndromic hearing loss 79; DFNB79; TPRN-related nonsyndromic hearing loss. Common historical names include deafness, autosomal recessive 79, nonsyndromic deafness DFNB79, C9orf75-related deafness, and taperin-related hearing loss.

The disease is generally catalogued in OMIM as Deafness, autosomal recessive 79 (DFNB79), OMIM #613307; TPRN is located at 9q34.3. The original study interrogated a 2.9-Mb DFNB79 interval containing 108 candidate genes and established C9orf75/TPRN as causal through linkage, sequencing, segregation, and protein-localization evidence (rehman2010targetedcaptureand pages 3-4, rehman2010targetedcaptureand pages 6-7, rehman2010targetedcaptureand pages 1-3). A disease-specific Orphanet, ICD-10, ICD-11, or MeSH code was not identified in the retrieved literature; clinically it is coded under broader congenital or sensorineural hearing-loss categories. A precise MONDO identifier could not be verified from the retrieved evidence and should be resolved directly against the current MONDO release rather than inferred.

Evidence provenance: the clinical description is aggregated from research pedigrees, not longitudinal EHR-derived population data. The foundational report analyzed four consanguineous Pakistani families—PKDF741, PKDF517, PKDF280, and PKDF1129 (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 1-3).

2. Etiology

Causal factor

DFNB79 is a germline, autosomal-recessive loss-of-function disorder. Disease results when an individual inherits pathogenic TPRN alleles on both homologues. The discovery variants were one nonsense and three frameshifting alleles, strongly supporting loss of functional taperin rather than gain of function (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 8-10).

Risk factors

  • Genetic: biallelic pathogenic/likely pathogenic TPRN variants; parental carrier status; family history compatible with recessive deafness; and parental relatedness, which increases homozygosity for rare alleles. The original families were consanguineous (rehman2010targetedcaptureand pages 1-3).
  • Population context: consanguinity increases the burden and discovery rate of autosomal-recessive nonsyndromic hearing loss generally. A 2024 review reported that individual rarer genes each account for less than 2% of profound hearing-loss cases in studied Pakistani cohorts, but it did not provide a TPRN-specific estimate.
  • Environmental, infectious, lifestyle, age, and sex risks: none are established as causes of DFNB79. Noise, aminoglycosides, cisplatin, meningitis, congenital CMV, and other exposures can independently worsen hearing but should not be represented as causes of the Mendelian disorder.

Protective factors and gene–environment interaction

No protective TPRN allele, modifier gene, diet, medication, or validated environmental intervention has been demonstrated. No DFNB79-specific gene–environment interaction has been established. Avoidance of excessive noise and ototoxic exposures is prudent hearing-conservation practice, but evidence that it changes the TPRN-specific natural history is absent.

3. Phenotypes

Core phenotype

The best-supported phenotype is bilateral, prelingual, severe-to-profound sensorineural hearing loss. Vestibular function was described as normal, and no consistent syndromic manifestations were reported in the original families (rehman2010targetedcaptureand pages 6-7, rehman2010targetedcaptureand pages 1-3).

Suggested phenotype annotations are:

  • Sensorineural hearing impairment — HP:0000407; clinical sign, bilateral and cochlear.
  • Bilateral sensorineural hearing impairment — HP:0008619 where accepted by the target HPO release.
  • Severe hearing impairment — HP:0012713 and/or profound hearing impairment — HP:0012714.
  • Prelingual hearing loss — HP:0012717.
  • Congenital hearing impairment — HP:0008527 only when objectively documented at birth; “prelingual” should not automatically be converted to “congenital.”
  • Progressive hearing impairment — HP:0001730 for patients/families with serially demonstrated progression. Progression is reported in some TPRN literature, but it should not be assigned universally because the discovery cohort was already severely affected before speech acquisition.
  • Normal vestibular function is a negative finding, not an HPO disease feature.

Published case numbers are too small to calculate defensible phenotype percentages, penetrance, or genotype–phenotype correlations. There is no well-defined behavioral, biochemical, hematologic, imaging, or systemic laboratory phenotype.

Functional and quality-of-life effects

Disease-specific patient-reported outcome data are unavailable. By extrapolation from congenital childhood hearing loss, delayed access to sound can affect spoken-language acquisition, education, social participation, cognition, and well-being. A 2023 review summarized consequences as impairment of “verbal communication, linguistic skills, educational progress, social integration, cognitive aptitude, and overall well-being.” These are general hearing-loss effects, not uniquely measured in DFNB79.

4. Genetic and molecular information

Gene and protein

  • Gene: TPRN; historical symbol C9orf75.
  • Locus: chromosome 9q34.3.
  • Product: taperin, a protein concentrated at the taper/base of inner- and outer-hair-cell stereocilia.
  • Gene architecture: the initially described open reading frame extended across four exons and encoded a 711-amino-acid protein; exon 1 encoded most of the protein. Human and mouse taperin showed approximately 68% identity and 75% similarity in the original comparison (rehman2010targetedcaptureand pages 5-6).

Transcript and protein lengths vary by reference isoform; consequently, clinical laboratories must report the exact transcript and genome build.

Landmark pathogenic variants

Rehman et al. reported four exon-1 truncating variants:

  1. c.1056G>A, p.Trp352Ter (originally p.W352X), family PKDF741;
  2. c.1244delC, family PKDF517;
  3. c.44_54dup, family PKDF280;
  4. c.42_52del, family PKDF1129.

The variants cosegregated with hearing loss and were absent from approximately 488–500 Pakistani control chromosomes and 400 Coriell control chromosomes tested at the time (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 8-10). They are germline variants. Frameshift/nonsense alleles are expected to produce nonsense-mediated decay or truncated protein, but transcript-specific NMD must be evaluated variant by variant.

These historical observations do not substitute for contemporary ACMG/AMP classification. Current classification should incorporate ClinVar assertions, segregation, phenotype specificity, predicted NMD, and current ancestry-matched gnomAD frequencies. No reliable current allele frequencies were available in the retrieved evidence; rarity should therefore be queried directly in the current gnomAD release. VUS must not be used alone for diagnosis or reproductive decision-making.

Modifiers, epigenetics, and structural variation

No human modifier gene or epigenetic lesion has been validated. Experimental interaction with GRXCR2, CLIC5, RDX, MYO6, PTPRQ, and related stereociliary-base proteins defines a functional network, not proven human modifiers. No recurrent TPRN deletion, inversion, translocation, aneuploidy, methylation signature, somatic mutation, or repeat expansion is established.

5. Environmental information

DFNB79 is not an infectious, toxic, nutritional, occupational, or lifestyle-induced condition. There is no evidence that smoking, alcohol, exercise, or diet alters penetrance. Acquired causes of hearing loss—congenital CMV, meningitis, hypoxia, noise, aminoglycosides, platinum chemotherapy, and trauma—remain relevant differential or additive insults. They should be separately captured rather than merged into TPRN etiology.

6. Mechanism and pathophysiology

Ordered causal chain

  1. Biallelic TPRN loss-of-function variants lead to absent, reduced, or truncated taperin.
  2. Deficient taperin leads to failure of normal protein organization at the taper/base of cochlear hair-cell stereocilia; this step is demonstrated mainly in mouse and cellular systems and inferred in human DFNB79.
  3. Disruption of the taperin-associated CLIC5–radixin–MYO6–PTPRQ/GRXCR2 membrane–actin complex leads to abnormal anchoring and regulation of stereociliary F-actin at the taper/rootlet region (liu2018grxcr2regulatestaperin pages 1-3, li2021nterminusofgrxcr2 pages 8-9).
  4. Abnormal taper/rootlet organization leads to malformed, elongated, disorganized, or progressively degenerating stereocilia and reduced mechanical stability (liu2018grxcr2regulatestaperin pages 1-3, liu2018grxcr2regulatestaperin pages 10-12).
  5. Stereociliary structural failure leads to impaired hair-bundle mechanotransduction and, with progression, hair-cell degeneration; direct TPRN-human temporal evidence is limited.
  6. Hair-cell dysfunction/loss leads to bilateral cochlear sensorineural hearing loss.

Mechanistic detail

Taperin is enriched at the stereociliary base, near the pointed ends of parallel actin filaments. The discovery study noted limited homology to phostensin and proposed regulation of actin dynamics, but that biochemical role was initially hypothetical (rehman2010targetedcaptureand pages 8-10). Later mouse work demonstrated that GRXCR2 restricts taperin to the base. In Grxcr2-deficient hair cells, taperin spreads along stereocilia, which become elongated and disorganized; reducing Tprn dosage rescues morphology and improves hearing. This is unusually strong genetic evidence that both taperin abundance and spatial restriction matter (liu2018grxcr2regulatestaperin pages 1-3, liu2018grxcr2regulatestaperin pages 10-12).

CLIC5 is cytoskeleton-associated at this site and forms a functional complex with radixin, taperin, and myosin VI. GRXCR2 also interacts with CLIC5; loss of either protein causes disorganized bundles and diffuse taperin localization (li2021nterminusofgrxcr2 pages 8-9). These data favor a structural/cytoskeletal mechanism over a canonical signaling-cascade, metabolic, inflammatory, or immune mechanism.

No reproducible DFNB79-specific abnormalities have been reported for Wnt, MAPK, PI3K–AKT, mTOR, autophagy, metabolism, immune activation, DNA methylation, lipidomics, or circulating proteomics. No human single-cell, spatial-transcriptomic, metabolomic, or multi-omic DFNB79 profile was identified.

Suggested GO terms: stereocilium organization (GO:0032429), actin filament organization (GO:0007015), actin cytoskeleton organization (GO:0030036), sensory perception of sound (GO:0007605), inner-ear receptor-cell stereocilium organization, and mechanosensory behavior where supported. Suggested cellular components include stereocilium (GO:0032420), stereocilium base, actin cytoskeleton (GO:0015629), and cuticular plate.

Suggested Cell Ontology terms: inner hair cell (CL:0000589, verify current release), outer hair cell (CL:0000601, verify current release), and auditory hair cell/sensory epithelial cell. The main upstream lesion is molecular/cytoskeletal; stereocilia degeneration, mechanotransduction failure, and hair-cell loss are downstream.

7. Anatomical structures affected

  • Organ/system: inner ear, principally the cochlea and auditory system.
  • Anatomical site: organ of Corti/cochlear sensory epithelium; suggested UBERON:0001844 (cochlea) and the current UBERON term for organ of Corti.
  • Cells: inner and outer cochlear hair cells.
  • Subcellular site: actin-rich stereocilia, particularly their taper/base and rootlet-associated membrane–cytoskeleton interface; cuticular plate involvement is downstream.
  • Laterality: bilateral in reported patients.
  • Secondary organs: none consistently involved. Normal reported vestibular function argues against routine labeling as vestibular disease, although formal testing remains reasonable when symptoms occur (rehman2010targetedcaptureand pages 1-3).

8. Temporal development

Human onset is usually prelingual; some reports describe progressive TPRN-associated hearing loss. The sparse literature supports a spectrum from early severe/profound loss to progressive deterioration rather than a rigorously defined stage system. The course is chronic and lifelong without auditory rehabilitation; spontaneous remission is not expected. Mouse evidence indicates progressive stereocilia and hair-cell pathology after development, supporting biologic plausibility for human progression (liu2018grxcr2regulatestaperin pages 10-12).

The critical clinical period is early childhood, when auditory access strongly influences language development. This supports prompt diagnostic audiology, amplification, cochlear-implant assessment, and communication intervention, but no TPRN-specific therapeutic window has been established.

9. Inheritance and population

Inheritance is autosomal recessive. For two confirmed heterozygous carrier parents, each pregnancy has a 25% probability of an affected child, 50% probability of a carrier, and 25% probability of inheriting neither familial allele. Males and females are expected to be affected equally.

Penetrance appears high for biallelic truncating alleles in reported pedigrees, but the sample is insufficient to claim complete penetrance. Expressivity includes variation in onset/progression and severity. Anticipation is not expected; germline mosaicism has not been specifically reported but remains a general residual counseling consideration.

The original evidence was enriched in Pakistani and North African/Moroccan consanguineous families, reflecting ascertainment and recessive mapping rather than proof of ancestry restriction. No global prevalence, incidence, sex ratio, carrier frequency, or robust founder-effect estimate exists for DFNB79. Broader congenital hearing loss occurs in approximately 1–3 per 1,000 births, and 2024 reviews estimate that 50–70% or more has a genetic basis; these figures must not be entered as DFNB79 prevalence (yun2024updatesongenetic pages 1-2, brotto2024autosomalrecessivenonsyndromic pages 1-2, lee2024clinicalgenetictesting pages 1-2).

10. Diagnostics

Clinical evaluation

Diagnosis begins with age-appropriate behavioral audiometry and objective testing: otoacoustic emissions, tympanometry, auditory brainstem response, and frequency-specific thresholds. Findings should establish bilateral sensorineural rather than conductive loss. Vestibular assessment is symptom-directed. CT or MRI is not diagnostic of DFNB79 but may be used before cochlear implantation or where anatomic/auditory-nerve abnormalities are suspected. There is no blood chemistry, enzyme assay, biopsy, histopathology, or circulating biomarker for DFNB79.

Molecular testing strategy

  1. Use a comprehensive hearing-loss multigene panel including TPRN, sequencing plus exon-level CNV analysis.
  2. If negative, consider exome or genome sequencing with CNV/structural-variant and mitochondrial analysis, followed by periodic reanalysis.
  3. In a family with known TPRN variants, use targeted familial testing for segregation, carrier testing, prenatal diagnosis, or preimplantation genetic testing.
  4. Confirm phase: two variants must be shown or strongly inferred to be in trans.

Contemporary panels have an approximately 40% diagnostic yield across heterogeneous hearing-loss cohorts—not specifically DFNB79. Whole-genome sequencing can detect noncoding and structural variants missed by conventional panel/exome analysis (yun2024updatesongenetic pages 1-2, lee2024clinicalgenetictesting pages 1-2). CMA, karyotyping, FISH, repeat-expansion testing, and isolated mitochondrial testing are not first-line tests for a classic biallelic TPRN phenotype unless other findings indicate them.

Differential diagnosis

The differential encompasses other recessive nonsyndromic hearing-loss genes, especially GJB2/GJB6, STRC, OTOF, SLC26A4, TMC1, TMPRSS3, MYO15A, CDH23, and many others; syndromic disorders such as Usher, Pendred, Alport, and mitochondrial disease; congenital CMV; auditory neuropathy; structural inner-ear anomalies; and acquired ototoxic/noise injury. A broad panel is preferable to phenotype-only single-gene guessing because more than 148–150 nonsyndromic hearing-loss genes are now recognized (yun2024updatesongenetic pages 1-2, lee2024clinicalgenetictesting pages 1-2).

Screening

Universal newborn hearing screening can identify early bilateral loss but does not identify TPRN etiology. Cascade testing is appropriate after a molecular diagnosis. Population-wide TPRN carrier screening is not currently evidence-based, although nonsyndromic hearing-loss genes are increasingly debated for reproductive carrier panels.

11. Outcome and prognosis

DFNB79 is not known to shorten life expectancy or cause disease-specific mortality. Its burden is auditory disability rather than systemic organ failure. Untreated severe/profound prelingual loss can substantially affect speech, education, social participation, and employment, but outcomes vary with communication modality, timing of intervention, family support, and access to services.

There are no TPRN-specific survival curves, quality-of-life scores, prognostic biomarkers, or validated prediction models. Residual hearing, progression rate, age at intervention, auditory-nerve integrity, and consistent rehabilitation are clinically relevant general prognostic factors. Because TPRN pathology is localized to sensory hair-cell stereocilia rather than known primary spiral-ganglion disease, cochlear implantation is mechanistically plausible; however, no adequately sized TPRN-specific outcome series was retrieved.

12. Treatment

Current management

There is no approved disease-modifying pharmacotherapy for TPRN-related hearing loss. Management is individualized:

  • hearing aids for aidable residual hearing;
  • cochlear-implant evaluation for bilateral severe-to-profound loss with insufficient aided benefit;
  • speech-language/auditory rehabilitation where spoken-language goals are chosen;
  • sign-language and multimodal communication access;
  • educational accommodations and psychosocial support;
  • serial audiometry where progression is possible.

Suggested NCIT intervention concepts include Hearing Aid, Cochlear Implantation, Speech and Language Therapy, Audiologic Rehabilitation, and Genetic Counseling; exact NCIT identifiers should be resolved against the deployed NCIT version.

No TPRN-specific response rate or adverse-event series exists. General cochlear-implant evidence in genetic hearing loss suggests sensory/non-neural cochlear disorders often perform at or above cohort medians, but extrapolation to DFNB79 remains indirect.

Experimental therapies and 2023–2024 context

As of the searched evidence, there was no TPRN-specific human gene-replacement, editing, RNA, cell-therapy, or drug trial. A 2024 review identified 17 preclinical and three clinical AAV programs across autosomal-recessive deafness, but the clinical programs targeted OTOF/DFNB9, not TPRN (brotto2024autosomalrecessivenonsyndromic pages 1-2, brotto2024autosomalrecessivenonsyndromic pages 3-5). Relevant OTOF trials included NCT05788536, NCT05821959, and NCT05901480; their results cannot be attributed to DFNB79.

The field nonetheless provides proof of concept. A 2024 bilateral OTOF study treated five children: all showed bilateral hearing restoration, with ABR thresholds improving from greater than 95 dB at baseline to approximately 50–85 dB at follow-up; no dose-limiting toxicity or serious adverse event occurred. This is encouraging for inner-ear gene therapy generally but is gene-, cell-, vector-, and timing-specific and does not demonstrate TPRN efficacy. Reviews emphasize that precision strategies are required because target-cell transduction and therapeutic windows differ across genes (yun2024updatesongenetic pages 1-2, duhon2024genetherapyadvancements pages 20-21, brotto2024autosomalrecessivenonsyndromic pages 3-5).

13. Prevention

The occurrence of a de novo inherited Mendelian allele cannot be prevented by lifestyle modification or vaccination.

  • Primary/reproductive: nondirective genetic counseling, partner testing, cascade carrier testing, preimplantation genetic testing, prenatal diagnosis, donor gametes, or natural conception with testing according to family values.
  • Secondary: universal newborn hearing screening, prompt diagnostic ABR/audiology, and early molecular testing.
  • Tertiary: amplification or implantation, communication access, rehabilitation, educational support, hearing conservation, and avoidance of unnecessary ototoxic exposure.

No vaccine, chemoprophylaxis, diet, or public-health exposure intervention prevents TPRN-related disease. Counseling should respect Deaf-community perspectives; reproductive screening for nonsyndromic hearing loss raises ethical concerns about disability framing and informed choice.

14. Other species and natural disease

The experimentally important ortholog is Tprn in the laboratory mouse, Mus musculus (NCBI Taxonomy 10090). Human and mouse proteins are substantially conserved, and the loci are syntenic (rehman2010targetedcaptureand pages 5-6). No well-established naturally occurring TPRN-associated veterinary disease or breed predisposition was identified. The condition is not transmissible or zoonotic.

15. Model organisms

Mouse models

Tprn-null/knockout mice are the principal disease models. They recapitulate progressive hearing loss, abnormal stereociliary taper/rootlet architecture, bundle degeneration, and subsequent hair-cell loss. These models support the causal sequence from taperin deficiency to structural hair-bundle failure and auditory dysfunction (liu2018grxcr2regulatestaperin pages 10-12).

Grxcr2-deficient mice provide a complementary pathway model: taperin is present but mislocalized along stereocilia, causing elongation and disorganization. Reduction of one Tprn allele substantially rescues stereocilia morphology and hearing, demonstrating a dosage-sensitive genetic interaction (liu2018grxcr2regulatestaperin pages 1-3, liu2018grxcr2regulatestaperin pages 10-12). Clic5-deficient models similarly disrupt the taperin/radixin/MYO6 complex and stereociliary-base organization (li2021nterminusofgrxcr2 pages 8-9).

Applications: defining stereociliary-base architecture, testing actin regulation, identifying therapeutic windows, evaluating hair-cell-targeted vectors, and distinguishing loss from mislocalization toxicity. Limitations: mouse cochlear maturation and auditory frequencies differ from humans; complete knockout may not model every hypomorphic allele; and rescue of developmental mouse pathology does not establish safety or efficacy in older human cochleae.

No validated TPRN patient iPSC, organoid, zebrafish, rat, Drosophila, or naturally occurring large-animal model was identified in the retrieved corpus.

Recent-development assessment and evidence limitations

The key 2023–2024 advances were primarily field-wide: broader clinical use of hearing-loss panels, increasing consideration of genome sequencing, and first-in-human successes for OTOF gene therapy. A June 2024 review stated that panels provide “comprehensive genetic testing,” while an April 2024 review emphasized that genome sequencing can detect “both noncoding and structural variations” (yun2024updatesongenetic pages 1-2, lee2024clinicalgenetictesting pages 1-2). These advances improve DFNB79 diagnosis and establish a translational roadmap, but they do not yet constitute TPRN-directed therapy.

A late-2024 paper titled Critical role of TPRN rings in the stereocilia for hearing was located bibliographically (Molecular Therapy; DOI: https://doi.org/10.1016/j.ymthe.2024.12.004), but its full evidence could not be retrieved in the available corpus. Its detailed quantitative claims are therefore not incorporated as established evidence here. Likewise, the second 2010 AJHG report (DOI: https://doi.org/10.1016/j.ajhg.2010.02.003) and a 2013 Pakistani-family report (DOI: https://doi.org/10.1007/s10528-013-9568-y) were bibliographically identified but not sufficiently accessible for exact case-level extraction. This report consequently relies most heavily on the directly retrieved Rehman et al. discovery study and later mechanistic papers.

Key references

  1. Rehman AU et al. Targeted capture and next-generation sequencing identifies C9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness DFNB79. American Journal of Human Genetics. March 2010;86:378–388. DOI: https://doi.org/10.1016/j.ajhg.2010.01.030. The study identified “four distinct truncating mutations” and localized taperin to the stereociliary taper region (rehman2010targetedcaptureand pages 5-6, rehman2010targetedcaptureand pages 1-3).
  2. Liu C et al. GRXCR2 regulates taperin localization critical for stereocilia morphology and hearing. Cell Reports. October 2018;25:1268–1280.e4. DOI: https://doi.org/10.1016/j.celrep.2018.09.063 (liu2018grxcr2regulatestaperin pages 1-3, liu2018grxcr2regulatestaperin pages 10-12).
  3. Li J et al. N-Terminus of GRXCR2 interacts with CLIC5 and is essential for auditory perception. Frontiers in Cell and Developmental Biology. May 2021. DOI: https://doi.org/10.3389/fcell.2021.671364 (li2021nterminusofgrxcr2 pages 8-9).
  4. Yun Y, Lee S-Y. Updates on Genetic Hearing Loss: From Diagnosis to Targeted Therapies. Journal of Audiology and Otology. April 2024;28:88–92. DOI: https://doi.org/10.7874/jao.2024.00157 (yun2024updatesongenetic pages 1-2).
  5. Brotto D et al. Autosomal Recessive Non-Syndromic Deafness: Is AAV Gene Therapy a Real Chance? Audiology Research. February 2024;14:239–253. DOI: https://doi.org/10.3390/audiolres14020022 (brotto2024autosomalrecessivenonsyndromic pages 1-2, brotto2024autosomalrecessivenonsyndromic pages 3-5).
  6. Lee NK et al. Clinical Genetic Testing for Hearing Loss: Implications for Genetic Counseling and Gene-Based Therapies. Biomedicines. June 2024;12:1427. DOI: https://doi.org/10.3390/biomedicines12071427 (lee2024clinicalgenetictesting pages 1-2, lee2024clinicalgenetictesting pages 9-11).

References

  1. (rehman2010targetedcaptureand pages 5-6): Atteeq Ur Rehman, Robert J. Morell, Inna A. Belyantseva, Shahid Y. Khan, Erich T. Boger, Mohsin Shahzad, Zubair M. Ahmed, Saima Riazuddin, Shaheen N. Khan, Sheikh Riazuddin, and Thomas B. Friedman. Targeted capture and next-generation sequencing identifies c9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness dfnb79. American journal of human genetics, 86 3:378-88, Mar 2010. URL: https://doi.org/10.1016/j.ajhg.2010.01.030, doi:10.1016/j.ajhg.2010.01.030. This article has 148 citations and is from a highest quality peer-reviewed journal.

  2. (rehman2010targetedcaptureand pages 1-3): Atteeq Ur Rehman, Robert J. Morell, Inna A. Belyantseva, Shahid Y. Khan, Erich T. Boger, Mohsin Shahzad, Zubair M. Ahmed, Saima Riazuddin, Shaheen N. Khan, Sheikh Riazuddin, and Thomas B. Friedman. Targeted capture and next-generation sequencing identifies c9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness dfnb79. American journal of human genetics, 86 3:378-88, Mar 2010. URL: https://doi.org/10.1016/j.ajhg.2010.01.030, doi:10.1016/j.ajhg.2010.01.030. This article has 148 citations and is from a highest quality peer-reviewed journal.

  3. (rehman2010targetedcaptureand pages 6-7): Atteeq Ur Rehman, Robert J. Morell, Inna A. Belyantseva, Shahid Y. Khan, Erich T. Boger, Mohsin Shahzad, Zubair M. Ahmed, Saima Riazuddin, Shaheen N. Khan, Sheikh Riazuddin, and Thomas B. Friedman. Targeted capture and next-generation sequencing identifies c9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness dfnb79. American journal of human genetics, 86 3:378-88, Mar 2010. URL: https://doi.org/10.1016/j.ajhg.2010.01.030, doi:10.1016/j.ajhg.2010.01.030. This article has 148 citations and is from a highest quality peer-reviewed journal.

  4. (rehman2010targetedcaptureand pages 8-10): Atteeq Ur Rehman, Robert J. Morell, Inna A. Belyantseva, Shahid Y. Khan, Erich T. Boger, Mohsin Shahzad, Zubair M. Ahmed, Saima Riazuddin, Shaheen N. Khan, Sheikh Riazuddin, and Thomas B. Friedman. Targeted capture and next-generation sequencing identifies c9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness dfnb79. American journal of human genetics, 86 3:378-88, Mar 2010. URL: https://doi.org/10.1016/j.ajhg.2010.01.030, doi:10.1016/j.ajhg.2010.01.030. This article has 148 citations and is from a highest quality peer-reviewed journal.

  5. (liu2018grxcr2regulatestaperin pages 1-3): Chang Liu, Na Luo, Chun-Yu Tung, Benjamin J. Perrin, and Bo Zhao. Grxcr2 regulates taperin localization critical for stereocilia morphology and hearing. Cell reports, 25:1268-1280.e4, Oct 2018. URL: https://doi.org/10.1016/j.celrep.2018.09.063, doi:10.1016/j.celrep.2018.09.063. This article has 32 citations and is from a highest quality peer-reviewed journal.

  6. (liu2018grxcr2regulatestaperin pages 10-12): Chang Liu, Na Luo, Chun-Yu Tung, Benjamin J. Perrin, and Bo Zhao. Grxcr2 regulates taperin localization critical for stereocilia morphology and hearing. Cell reports, 25:1268-1280.e4, Oct 2018. URL: https://doi.org/10.1016/j.celrep.2018.09.063, doi:10.1016/j.celrep.2018.09.063. This article has 32 citations and is from a highest quality peer-reviewed journal.

  7. (li2021nterminusofgrxcr2 pages 8-9): Jinan Li, Chang Liu, and Bo Zhao. N-terminus of grxcr2 interacts with clic5 and is essential for auditory perception. Frontiers in Cell and Developmental Biology, May 2021. URL: https://doi.org/10.3389/fcell.2021.671364, doi:10.3389/fcell.2021.671364. This article has 12 citations.

  8. (yun2024updatesongenetic pages 1-2): Yejin Yun and Sang-Yeon Lee. Updates on genetic hearing loss: from diagnosis to targeted therapies. Journal of Audiology and Otology, 28:88-92, Apr 2024. URL: https://doi.org/10.7874/jao.2024.00157, doi:10.7874/jao.2024.00157. This article has 7 citations.

  9. (brotto2024autosomalrecessivenonsyndromic pages 1-2): Davide Brotto, Marco Greggio, Cosimo De Filippis, and Patrizia Trevisi. Autosomal recessive non-syndromic deafness: is aav gene therapy a real chance? Audiology Research, 14:239-253, Feb 2024. URL: https://doi.org/10.3390/audiolres14020022, doi:10.3390/audiolres14020022. This article has 8 citations.

  10. (lee2024clinicalgenetictesting pages 1-2): Nam K. Lee, Kristin M. Uhler, Patricia J. Yoon, and Regie Lyn P. Santos-Cortez. Clinical genetic testing for hearing loss: implications for genetic counseling and gene-based therapies. Biomedicines, 12:1427, Jun 2024. URL: https://doi.org/10.3390/biomedicines12071427, doi:10.3390/biomedicines12071427. This article has 6 citations.

  11. (lee2024clinicalgenetictesting pages 9-11): Nam K. Lee, Kristin M. Uhler, Patricia J. Yoon, and Regie Lyn P. Santos-Cortez. Clinical genetic testing for hearing loss: implications for genetic counseling and gene-based therapies. Biomedicines, 12:1427, Jun 2024. URL: https://doi.org/10.3390/biomedicines12071427, doi:10.3390/biomedicines12071427. This article has 6 citations.

  12. (duhon2024genetherapyadvancements pages 20-21): Bailey H. Duhon, Eric C. Bielefeld, Yin Ren, and Jerusha Naidoo. Gene therapy advancements for the treatment of acquired and hereditary hearing loss. Frontiers in Audiology and Otology, Jul 2024. URL: https://doi.org/10.3389/fauot.2024.1423853, doi:10.3389/fauot.2024.1423853. This article has 9 citations.

  13. (brotto2024autosomalrecessivenonsyndromic pages 3-5): Davide Brotto, Marco Greggio, Cosimo De Filippis, and Patrizia Trevisi. Autosomal recessive non-syndromic deafness: is aav gene therapy a real chance? Audiology Research, 14:239-253, Feb 2024. URL: https://doi.org/10.3390/audiolres14020022, doi:10.3390/audiolres14020022. This article has 8 citations.

  14. (lee2024clinicalgenetictesting pages 12-13): Nam K. Lee, Kristin M. Uhler, Patricia J. Yoon, and Regie Lyn P. Santos-Cortez. Clinical genetic testing for hearing loss: implications for genetic counseling and gene-based therapies. Biomedicines, 12:1427, Jun 2024. URL: https://doi.org/10.3390/biomedicines12071427, doi:10.3390/biomedicines12071427. This article has 6 citations.

  15. (rehman2010targetedcaptureand pages 3-4): Atteeq Ur Rehman, Robert J. Morell, Inna A. Belyantseva, Shahid Y. Khan, Erich T. Boger, Mohsin Shahzad, Zubair M. Ahmed, Saima Riazuddin, Shaheen N. Khan, Sheikh Riazuddin, and Thomas B. Friedman. Targeted capture and next-generation sequencing identifies c9orf75, encoding taperin, as the mutated gene in nonsyndromic deafness dfnb79. American journal of human genetics, 86 3:378-88, Mar 2010. URL: https://doi.org/10.1016/j.ajhg.2010.01.030, doi:10.1016/j.ajhg.2010.01.030. This article has 148 citations and is from a highest quality peer-reviewed journal.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome Count
References checked 10
Resolved 10
Unresolved (possible confabulation) 0
Unverifiable 0
References weighed for topical relevance 10
On topic 5
Off topic 0

All extracted references resolved successfully.

Term Validation

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

Outcome Count
Terms checked 16
Resolved 15
Unresolved (possible confabulation) 0
Obsolete 1
Unverifiable 0

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

  • GO:0032429 (obsolete regulation of phospholipase A2 activity) (1 mention)

15 of 16 terms resolved to a current term; the rest could not be looked up either way.