Autosomal Recessive Nonsyndromic Hearing Loss 123

Mendelian MONDO:0958277 Pathograph 9 Show in embeddings browser Autosomal Recessive Nonsyndromic Hearing Loss

DFNB123 is bilateral, severe-to-profound, nonsyndromic hearing impairment caused by biallelic variants in STX4, which encodes syntaxin-4, a target-SNARE of the plasma membrane. The entity rests on a single large consanguineous Pakistani family with eight affected individuals, homozygous for a splice-region variant that causes exon skipping and a frameshift. The segregation is strong for one family - a two-point LOD of 5.9 - and the supporting work is expression, localisation and a zebrafish knockdown rather than anything done in human cochlear tissue. Where this sits mechanistically is worth stating, because it is not the usual hair-bundle story. STX4 is a general membrane-fusion protein: it is the t-SNARE half of the machinery that docks and fuses vesicles at the plasma membrane, and it works in many tissues. What makes it a deafness gene is where it is found and what happens when it is removed. The murine orthologue is widely expressed through the developing and adult inner ear, the protein sits in the cell body, plasma membrane and stereocilia of both inner and outer hair cells, and knocking the fish orthologue down disrupts mechanotransduction in neuromast hair cells as well as producing an abnormal startle response. So the proposed lesion is a failure of membrane trafficking in the hair cell, read out as a transduction defect. What the trafficked cargo is, and which of the three subcellular pools of STX4 matters, is not established. A second STX4 phenotype exists and is not the same disease. A separate group reported two patients with damaging STX4 variants whose presentation was syndromic - dilated cardiomyopathy with ventricular ectopy, sensorineural hearing loss, developmental delay and hypotonia in one, and perinatal lethality with severe pleiotropic abnormalities in the other - and showed that the missense allele in the first is hypomorphic. This entry curates DFNB123, the nonsyndromic entity, and records the relationship between the two as an open question rather than merging them. Which one a given STX4 genotype produces is exactly the kind of question a dose-dependent allelic series raises, and nobody has tested it. OMIM flags the gene-phenotype relationship as provisional: NCBI mim2gene_medgen carries the `question` comment on OMIM:620745, its marker for a gene-map phenotype entered with a leading question mark. That is consistent with the evidence base - one family, however well it segregates, plus non-human functional support.

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Inheritance
5
Pathophys.
1
Phenotypes
2
Gaps
9
Pathograph
1
Genes
1
Medical Actions
2
Models
2
References
1
Deep Research
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Inheritance

1
Autosomal recessive HP:0000007
One large consanguineous Pakistani family with eight affected individuals, all homozygous for the STX4 splice-region variant, which segregated with hearing impairment at a two-point LOD of 5.9. No heterozygote is reported as affected. The syndromic STX4 patient described separately is also homozygous, for a missense allele.
Autosomal recessive inheritance
Show evidence (1 reference)
PMID:36355422 SUPPORT Human Clinical
"This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
Homozygosity, the segregation result and its statistical strength in one sentence. A two-point LOD of 5.9 in a single pedigree is well above the conventional threshold of 3.3.
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Discussions and Knowledge Gaps

2
Why does one biallelic STX4 genotype give isolated deafness while another gives dilated cardiomyopathy, developmental delay and, in one case, perinatal lethality?
KNOWLEDGE GAP OPEN dfnb123_nonsyndromic_versus_syndromic_stx4
Attached to
pathophysiology#STX4 Biallelic Loss of Function genetic#STX4
Two groups have reported biallelic STX4 disease and the pictures do not overlap. The DFNB123 family, homozygous for a splice allele causing exon skipping and a frameshift, has hearing impairment and nothing else in eight affected members. The separately reported patients, one homozygous for the missense allele p.Arg240Trp, have cardiomyopathy with ventricular ectopy, sensorineural hearing loss, developmental delay and hypotonia, or perinatal lethality with severe pleiotropic abnormalities. The zebrafish null has both an ear and a heart phenotype, which is what one would expect of a gene used everywhere. The obvious reading - a dose-dependent allelic series - is complicated by its direction. The zebrafish equivalent of the missense allele is hypomorphic, so the patients with the milder allele have the more severe, multi-system disease, while the family with a frameshift has isolated deafness. That is the wrong way round for a simple dosage model, and it is the reason this is filed as an open question rather than written into the entry as an allelic series. Residual protein from the skipped-exon transcript, modifier background, and ascertainment (a deafness study would not look for subclinical cardiomyopathy) are all live alternatives, and none has been tested. It matters clinically: if the two are one disease, DFNB123 patients need cardiac surveillance. One partial answer exists and is recorded here with its provenance, because it cannot be given a verified snippet. The deep-research report committed with this entry reads the full text of the defining paper and states that electrocardiograms were normal in two tested affected relatives of the DFNB123 family, and that no consistent vestibular, facial, neurologic or cardiac abnormality was found. The cached reference for PMID:36355422 is abstract-only, and that sentence is not in the abstract, so no evidence item can carry it. Two normal ECGs in eight affected individuals is in any case a weak negative - it is not echocardiography, and cardiomyopathy in the syndromic patient was dilated rather than electrical - so it narrows the question rather than closing it.
Proposed experiments
Transcript quantification of the DFNB123 allele, plus cardiac assessment of the family
dfnb123_stx4_allele_series_and_cardiac_surveillance
Measure STX4 transcript and protein from patient-derived cells homozygous for c.232+6T>C, to establish whether the skipped-exon allele is a true null or leaves residual product; and echocardiography with electrocardiography in the affected family members, reported whether normal or abnormal.
Readouts
Residual STX4 protein in patient cells
pathophysiology#STX4 Biallelic Loss of Function
Direction: DECREASED
Interpretation: A true null in patients with isolated deafness would refute the simple dosage model outright and point at tissue-specific compensation or modifiers.
Left ventricular ejection fraction in DFNB123 family members
phenotypes#Bilateral Severe-to-Profound Hearing Impairment
Interpretation: Subclinical cardiomyopathy in the deafness family would unify the two reports and make cardiac surveillance part of managing DFNB123. A normal result across eight affected members would establish that the phenotypes really are separable.
Does loss of Stx4 impair hearing in a mammal, and does it do so through the cochlear hair cells where STX4A is localised?
HUMAN MODEL MISMATCH OPEN dfnb123_no_mammalian_ear_model
Attached to
pathophysiology#Hair Cell Mechanotransduction Failure
The mechanistic claim in this entry rests on a zebrafish morpholino knockdown assayed in neuromast hair cells. Those are lateral-line cells; a fish has no cochlea, no endocochlear potential and no outer hair cell amplifier. The mammalian evidence is expression and immunolocalisation only - Stx4a is present through the mouse inner ear and STX4A sits in the cell body, membrane and stereocilia of inner and outer hair cells - and expression is not function. No mouse with an inner ear Stx4 deletion has been reported, and a constitutive knockout would be confounded by the gene's roles elsewhere. Filed as a human-model mismatch rather than a knowledge gap because the experiment was done, in a model whose fidelity to the human cochlea is the open question, rather than not done at all.
Proposed experiments
Hair-cell-conditional Stx4 knockout mouse
dfnb123_hair_cell_conditional_stx4_mouse
A floxed Stx4 allele crossed to a hair-cell Cre, with auditory brainstem response and distortion-product otoacoustic emission thresholds, endocochlear potential measurement, and hair bundle morphology, compared against littermate controls.
Readouts
Auditory brainstem response threshold
pathophysiology#Hair Cell Mechanotransduction Failure
Direction: INCREASED
Interpretation: Raised thresholds in a hair-cell-restricted knockout would establish both that Stx4 is required for mammalian hearing and that it acts in the hair cell, which is the step the fish data cannot supply.
Endocochlear potential
pathophysiology#Hair Cell Mechanotransduction Failure
Interpretation: A normal endocochlear potential alongside raised thresholds would separate this mechanism from the lateral-wall deafness genes and confirm the lesion is in the hair cell itself.
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Pathophysiology

5
STX4 Biallelic Loss of Function
Homozygosity for a splice-region variant, c.232+6T>C, which causes exon skipping and a consequent frameshift. A frameshift early in the transcript predicts a truncated product or nonsense-mediated decay, so this is treated as a loss-of-function allele; that prediction has not been confirmed by measuring STX4 protein in patient cells. The missense allele p.Arg240Trp reported in the syndromic STX4 patients is a different kind of change, and its zebrafish equivalent was shown to be hypomorphic rather than null. The two alleles are noted together because the contrast is the most likely explanation for the two different clinical pictures, but they are not pooled: only the splice allele belongs to DFNB123.
STX4 hgnc:11439 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves STX4 (hgnc:11439). hgnc:11439 is a gene from the HUGO Gene Nomenclature Committee.
Genetic context STX4 hgnc:11439 HUGO Gene Nomenclature Committee (hgnc) Relation: this genetic context concerns this gene This genetic context concerns STX4 (hgnc:11439). hgnc:11439 is a gene from the HUGO Gene Nomenclature Committee. allele_type: splice region variant causing exon skipping and frameshift variant_origin: GERMLINE zygosity: HOMOZYGOUS functional_impact_category: LOSS_OF_FUNCTION
LOSS_OF_FUNCTION is recorded as the consequence class of the DFNB123 allele, on the strength of the reported exon skipping and frameshift. It is a prediction from the splicing result, not a measurement of residual STX4 activity, and no patient-derived material has been assayed.
Downstream
Failure of SNARE-Mediated Membrane Fusion
Show evidence (2 references)
PMID:36355422 SUPPORT Human Clinical
"This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
The allele, its molecular consequence, and the evidence that it is the cause.
PMID:35599850 SUPPORT INDIRECT Model Organism
"Transgenic overexpression of zebrafish Stx4R241W, analogous to the first patient's STX4R240W variant, indicated that the variant is hypomorphic."
Cited for the contrast rather than for DFNB123 itself: the syndromic patients carry a partial-function allele, which is why a frameshift allele producing a different phenotype is not a contradiction. INDIRECT because it is a statement about a different variant in a different species.
Failure of SNARE-Mediated Membrane Fusion
Syntaxin-4 is a target-SNARE: it sits in the plasma membrane and pairs with vesicle SNAREs to drive the fusion step of vesicle delivery and recycling. Losing it removes one half of that pairing, so vesicles reach the membrane but do not dock and fuse normally. The direct demonstration of that failure is in zebrafish heart, where Vamp2-positive vesicles show reduced docking at the cardiomyocyte sarcolemma in stx4 mutants. Nothing equivalent has been imaged in a hair cell, so the fusion defect is established for the protein and assumed for the ear.
vesicle fusion at the plasma membrane GO:0006906 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased vesicle fusion at the plasma membrane, annotated with vesicle fusion (GO:0006906). GO:0006906 is a biological process from the Gene Ontology. ↓ DECREASED vesicle-mediated transport GO:0016192 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased vesicle-mediated transport (GO:0016192). GO:0016192 is a biological process from the Gene Ontology. ↓ DECREASED
SNARE binding GO:0000149 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased SNARE binding (GO:0000149). GO:0000149 is a molecular function from the Gene Ontology. ↓ DECREASED
plasma membrane GO:0005886 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves plasma membrane (GO:0005886). GO:0005886 is a cellular component from the Gene Ontology.
Downstream
Loss of Syntaxin-4 from the Hair Cell Membrane and Stereocilia
Show evidence (2 references)
PMID:36355422 SUPPORT BACKGROUND Human Clinical
"STX4, a member of the syntaxin family, is a component of the SNARE machinery involved in several vesicle transport and recycling pathways."
The molecular identity of the gene product. BACKGROUND because it restates established cell biology rather than reporting this paper's own result.
PMID:35599850 SUPPORT INDIRECT Model Organism
"Imaging of Vamp2+ vesicles within stx4 mutant zebrafish hearts showed reduced docking to the cardiomyocyte sarcolemma."
The one direct measurement of the fusion defect caused by loss of Stx4 in a vertebrate. INDIRECT because it was made in cardiomyocytes, not hair cells; it establishes that the protein is required for docking, not that this is what fails in the cochlea.
Loss of Syntaxin-4 from the Hair Cell Membrane and Stereocilia
The reason a general trafficking protein produces isolated deafness is where it is. The murine orthologue Stx4a is highly and widely expressed through the developing and adult inner ear, and immunofluorescence puts STX4A in three places in both inner and outer hair cells: the cell body, the plasma membrane, and the stereocilia. Stereocilial localisation is the finding that connects a fusion protein to mechanotransduction, because that is where the transduction machinery sits. Which of the three pools carries the disease-relevant function is not known, and no patient hair cell has been examined.
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 GO:0032420 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves stereocilium (GO:0032420). GO:0032420 is a cellular component from the Gene Ontology.
spiral organ of the cochlea UBERON:0002227 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in spiral organ of the cochlea, annotated with spiral organ of cochlea (UBERON:0002227). UBERON:0002227 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Hair Cell Mechanotransduction Failure
Disturbed Inner Ear Development
Show evidence (2 references)
PMID:36355422 SUPPORT Model Organism
"In silico analysis showed that murine orthologue Stx4a is highly and widespread expressed in the developing and adult inner ear."
The expression argument. Graded MODEL_ORGANISM because the data are mouse, and worth noting that the analysis was in silico over existing expression resources rather than a new measurement.
PMID:36355422 SUPPORT Model Organism
"Immunofluorescent imaging revealed localization of STX4A in the cell body, cell membrane and stereocilia of inner and outer hair cells."
The subcellular localisation, including the stereocilial pool that links the protein to transduction.
Hair Cell Mechanotransduction Failure
Knocking down stx4 in zebrafish disrupts mechanotransduction in neuromast hair cells, measured by FM1-43 uptake - the dye enters hair cells through open transduction channels, so reduced uptake reports that the channels are not passing current. The behavioural counterpart in the same animals is an abnormal startle response, which is the whole-animal readout of hair cell function in a larval fish. This is the node that carries the entity's mechanistic claim, and it is entirely non-mammalian. Neuromast hair cells are lateral-line cells, not cochlear ones, and no mammalian Stx4 hearing model has been reported. The cell type bound here is the human cochlear inner hair cell, because that is what the node is about; the measurement behind it was made in a zebrafish neuromast hair cell, and the gap between the two is the subject of this entry's human-model-mismatch discussion rather than something the binding hides. The bound process is the detection step rather than the perception it serves. An earlier version bound GO:0050954 sensory perception of mechanical stimulus and GO:0007605 sensory perception of sound, both of which are organism-level processes sitting on a node tagged CELLULAR. GO:0050910 is the cellular transduction event that FM1-43 uptake actually reports, so it matches both the scale tag and the assay.
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.
hair cell mechanotransduction GO:0050910 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased hair cell mechanotransduction, annotated with detection of mechanical stimulus involved in sensory perception of sound (GO:0050910). GO:0050910 is a biological process from the Gene Ontology. ↓ DECREASED
Animal models
stx4 morpholino knockdown zebrafish Zebrafish recapitulates FM1-43 uptake in neuromast hair cells is a direct cellular measurement of mechanotransduction, at the scale of the node.
Downstream
Bilateral Severe-to-Profound Hearing Impairment
Show evidence (2 references)
PMID:36355422 SUPPORT Model Organism
"a morpholino-based knockdown of stx4 in zebrafish showed an abnormal startle response, morphological and developmental defects, and a disrupted mechanotransduction function in neuromast hair cells measured via FM1-43 uptake"
The functional result, its readout, and the behavioural correlate, all from the morpholino knockdown.
PMID:36355422 SUPPORT Model Organism
"Our findings indicate that STX4 dysfunction leads to HI in humans and zebrafish and supports the evolutionary conserved role of STX4 in inner ear development and hair cell functioning."
The conclusion the paper draws, which names both strands of the mechanism this entry curates: development and hair cell function.
Disturbed Inner Ear Development
The second strand of the mechanism, and the weaker one. Stx4a is expressed in the developing as well as the adult inner ear, morpholino knockdown produces developmental defects in zebrafish, and CRISPR-generated stx4 mutant fish show frank otic vesicle dysgenesis. Whether anything corresponding happens in a human cochlea is unknown: no imaging of the inner ear is reported for any DFNB123 patient, and severe-to-profound loss with no other feature is compatible with a purely functional lesion.
inner ear development GO:0048839 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased inner ear development (GO:0048839). GO:0048839 is a biological process from the Gene Ontology. ↓ DECREASED
Animal models
stx4 CRISPR mutant zebrafish Zebrafish partially recapitulates Otic vesicle dysgenesis is a direct tissue-level observation of disturbed ear development.
Downstream
Bilateral Severe-to-Profound Hearing Impairment
Show evidence (1 reference)
PMID:35599850 SUPPORT INDIRECT Model Organism
"CRISPR/Cas9-generated stx4 mutant zebrafish exhibited defects reminiscent of these patients' clinical presentations, including linearized hearts, bradycardia, otic vesicle dysgenesis, neuronal atrophy, and touch insensitivity by 3 days post fertilization."
The otic vesicle phenotype in a genetic null fish, which is the strongest evidence that loss of Stx4 disturbs ear development rather than only ear function. INDIRECT because it comes from the syndromic-STX4 paper and from a fish, so it is two steps from the DFNB123 claim.
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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 123 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

1
Bilateral Severe-to-Profound Hearing Impairment OBLIGATE Ear HP:0012714 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Bilateral severe-to-profound hearing impairment, annotated with Severe hearing impairment (HP:0012714). HP:0012714 is a phenotype from the Human Phenotype Ontology.
OBLIGATE with a denominator of eight affected individuals in one family. A nonsyndromic deafness entity is ascertained through its hearing loss, so the band carries no information about penetrance. On the binding being narrower than the claim: HPO splits the severity axis into HP:0012714 Severe hearing impairment and HP:0012715 Profound hearing impairment, with no combined severe-to-profound term and no bilateral term that leaves the sensorineural question open. Checked against the live ontology on 2026-09-17. The entry therefore binds the lower bound of the reported range and carries the full range in preferred_term. A second phenotype for the profound end is not curated because no per-individual audiogram is reported, so it would have no denominator and could not be given a frequency band. The deep-research report committed with this entry independently suggests HP:0000407, HP:0008619, HP:0012714 and HP:0012715 for this phenotype, which corroborates the choice without resolving the range problem. Two details are deliberately absent because the source does not supply them. Age of onset is not stated in the abstract, so no onset phenotype is curated even though OMIM summarises the entity as beginning within the first decade - and the deep-research report reaches the same conclusion from the full text, noting that the publication describes congenital hearing impairment at study level while the individual data do not establish onset in every relative. Audiometric configuration and laterality asymmetry are likewise not reported in the abstract.
Show evidence (1 reference)
PMID:36355422 SUPPORT Human Clinical
"we used exome sequencing to investigate a large consanguineous Pakistani family with eight affected individuals showing bilateral severe-to-profound HI"
The phenotype, its laterality, its severity range, and the number of affected individuals it was observed in.
🧬

Genetic Associations

1
STX4
Gene: STX4 hgnc:11439 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is STX4 (hgnc:11439). hgnc:11439 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Show evidence (2 references)
PMID:36355422 SUPPORT Human Clinical
"This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
The causative allele and the segregation evidence for it.
PMID:35599850 SUPPORT Human Clinical
"A patient with a homozygous R240W missense variant displayed biventricular dilated cardiomyopathy, ectopy, and runs of non-sustained ventricular tachycardia, sensorineural hearing loss, global developmental delay, and hypotonia, while a second patient displayed severe pleiotropic abnormalities..."
The other end of the STX4 phenotypic spectrum, recorded here so that a curator reading only the DFNB123 entry is not surprised by a cardiomyopathy report. These patients are not DFNB123 and their features are not curated as phenotypes of it.
🗃️

External Assertions

1
OMIM deafness, autosomal recessive 123 record
OMIM disease record OMIM:620745
The OMIM phenotype record under which DFNB123 was designated, based on the Pakistani family reported by Schrauwen et al. Recorded here rather than under mappings because the DiseaseMappings class carries only ICD-10-CM, ICD-11, MONDO and NCIT slots. NCBI mim2gene_medgen maps this MIM number to GeneID 6810 (STX4) with source GeneMap and the comment `question`, marking the gene-phenotype relationship as provisional in OMIM.
Show evidence (1 reference)
PMID:36355422 SUPPORT Human Clinical
"This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
The gene-disease finding on which the OMIM designation rests.
💊

Medical Actions

1
Genetic Counselling and Cascade Testing
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: Behavioral / lifestyle
Counselling for a recessive condition in a consanguineous family with eight affected members, where the sibling recurrence risk is 25 percent and carrier frequency within the kindred is high. Counselling does not act on the mechanism; it is curated because it is the only intervention the genotype itself indicates.
Show evidence (1 reference)
PMID:36355422 SUPPORT Human Clinical
"This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
The segregating homozygous allele in a consanguineous pedigree, which is what carrier testing and recurrence counselling act on.
🔬

Diagnosis

1
STX4 sequencing in unexplained bilateral severe-to-profound hearing impairment
The family was solved by exome sequencing performed for undiagnosed recessive hearing impairment; STX4 was not a hearing-loss gene when the work was done. The practical consequence is that an exome or panel report predating 2023 will not have considered STX4, and that a splice-region variant six bases into the intron is the kind of change a filtering pipeline tuned to canonical splice sites can drop.
Show evidence (2 references)
PMID:36355422 SUPPORT Human Clinical
"we used exome sequencing to investigate a large consanguineous Pakistani family with eight affected individuals showing bilateral severe-to-profound HI"
The test that made the diagnosis, and the clinical setting it was used in.
PMID:36355422 SUPPORT BACKGROUND Human Clinical
"Congenital hearing impairment (HI) is a genetically highly heterogeneous disorder in which prompt recognition and intervention are crucial to optimize outcomes."
The argument for testing at all. BACKGROUND because it is the paper's opening framing of the field, not a finding about this family, and it is quoted only for the heterogeneity and early-intervention points rather than as a statement that this family had congenital onset.
📈

Progression

1
Unknown
Nothing is published. The report gives no age of onset, no serial audiometry and no follow-up, so whether DFNB123 is stable or progressive is unknown. This phase exists to record that absence rather than to describe a course, and nothing is imported from the zebrafish, whose developmental time course would not be a human natural history.
📊

Prevalence

1
Worldwide
Cases In Literature Ultra Rare
No prevalence estimate exists. One family has been reported, in one 2023 paper. No second family carrying a nonsyndromic STX4 genotype has been published, so there is no denominator of any kind and no rate is recorded.
Show evidence (1 reference)
PMID:36355422 SUPPORT Human Clinical
"we used exome sequencing to investigate a large consanguineous Pakistani family with eight affected individuals showing bilateral severe-to-profound HI"
The whole published case series, which is a single pedigree.
🐁

Animal Models

2
stx4 morpholino knockdown zebrafish
The functional model behind DFNB123. Knockdown larvae have an abnormal startle response, morphological and developmental defects, and reduced FM1-43 uptake in neuromast hair cells, which reports loss of mechanotransduction.
Species
Zebrafish
Genotype
transient morpholino knockdown of stx4
Publication
PMID:36355422
Pathograph links
Hair Cell Mechanotransduction Failure recapitulates fidelity: low observes: cellular FM1-43 uptake in neuromast hair cells is a direct cellular measurement of mechanotransduction, at the scale of the node.
Limitations: Three separate gaps sit between this model and the human disease. Neuromast hair cells belong to the lateral line, not the cochlea, and a fish has no cochlea at all. The knockdown is a transient morpholino rather than a genetic null, so residual protein and off-target effects are not excluded. And the knockdown removes stx4 from the whole embryo, so a hair cell defect is not shown to be cell-autonomous. Fidelity is graded LOW for those reasons and not because the result is weak.
Readouts
FM1-43 uptake in neuromast hair cells
Direction: DECREASED
Interpretation: The dye enters hair cells through open mechanotransduction channels, so reduced uptake reports that transduction is not working.
Show evidence (1 reference)
PMID:36355422 SUPPORT Model Organism
"a disrupted mechanotransduction function in neuromast hair cells measured via FM1-43 uptake"
The measurement and the assay used to make it.
Startle response
Direction: ALTERED
Interpretation: The whole-animal behavioural correlate of hair cell function in a larval fish.
Show evidence (1 reference)
PMID:36355422 SUPPORT Model Organism
"a morpholino-based knockdown of stx4 in zebrafish showed an abnormal startle response"
The behavioural readout in the knockdown larvae.
Show evidence (1 reference)
PMID:36355422 SUPPORT Model Organism
"Our findings indicate that STX4 dysfunction leads to HI in humans and zebrafish and supports the evolutionary conserved role of STX4 in inner ear development and hair cell functioning."
The authors' own claim that the fish result is informative for the human phenotype, which is what this link records.
stx4 CRISPR mutant zebrafish
A genetic null fish made for the cardiac phenotype, which also has otic vesicle dysgenesis and touch insensitivity. It is included here because it is the only genetic (as opposed to morpholino) loss-of-function animal in which ear phenotypes have been looked at.
Species
Zebrafish
Genotype
CRISPR/Cas9-generated stx4 mutant
Publication
PMID:35599850
Pathograph links
Disturbed Inner Ear Development partially recapitulates fidelity: low observes: tissue Otic vesicle dysgenesis is a direct tissue-level observation of disturbed ear development.
Limitations: The otic vesicle is the embryonic precursor of the whole inner ear in a fish and is not a cochlea; no human DFNB123 patient has had inner ear imaging, so there is no human counterpart to compare with. The model was also made and characterised for a cardiac phenotype that DFNB123 patients do not have, which is itself the open question this entry files as a discussion.
Show evidence (1 reference)
PMID:35599850 SUPPORT Model Organism
"CRISPR/Cas9-generated stx4 mutant zebrafish exhibited defects reminiscent of these patients' clinical presentations, including linearized hearts, bradycardia, otic vesicle dysgenesis, neuronal atrophy, and touch insensitivity by 3 days post fertilization."
The ear phenotype of the genetic null, alongside the cardiac one.
The cardiac phenotype of this model - linearized hearts, bradycardia, reduced vesicle docking at the sarcolemma, reduced L-type calcium channel modulation - is deliberately not linked to any node in this entry. DFNB123 patients have no reported cardiac phenotype, and importing one would assert a feature the family does not have.
{ }

Source YAML

click to show 
name: Autosomal Recessive Nonsyndromic Hearing Loss 123
category: Mendelian
creation_date: "2026-09-17T00:00:00Z"
synonyms:
- DFNB123
- deafness, autosomal recessive 123
- hearing loss, autosomal recessive 123
- STX4-related nonsyndromic hearing loss
description: >-
  DFNB123 is bilateral, severe-to-profound, nonsyndromic hearing impairment caused by
  biallelic variants in STX4, which encodes syntaxin-4, a target-SNARE of the plasma
  membrane.

  The entity rests on a single large consanguineous Pakistani family with eight affected
  individuals, homozygous for a splice-region variant that causes exon skipping and a
  frameshift. The segregation is strong for one family - a two-point LOD of 5.9 - and the
  supporting work is expression, localisation and a zebrafish knockdown rather than anything
  done in human cochlear tissue.

  Where this sits mechanistically is worth stating, because it is not the usual hair-bundle
  story. STX4 is a general membrane-fusion protein: it is the t-SNARE half of the machinery
  that docks and fuses vesicles at the plasma membrane, and it works in many tissues. What
  makes it a deafness gene is where it is found and what happens when it is removed. The
  murine orthologue is widely expressed through the developing and adult inner ear, the
  protein sits in the cell body, plasma membrane and stereocilia of both inner and outer hair
  cells, and knocking the fish orthologue down disrupts mechanotransduction in neuromast hair
  cells as well as producing an abnormal startle response. So the proposed lesion is a
  failure of membrane trafficking in the hair cell, read out as a transduction defect. What
  the trafficked cargo is, and which of the three subcellular pools of STX4 matters, is not
  established.

  A second STX4 phenotype exists and is not the same disease. A separate group reported two
  patients with damaging STX4 variants whose presentation was syndromic - dilated
  cardiomyopathy with ventricular ectopy, sensorineural hearing loss, developmental delay
  and hypotonia in one, and perinatal lethality with severe pleiotropic abnormalities in the
  other - and showed that the missense allele in the first is hypomorphic. This entry curates
  DFNB123, the nonsyndromic entity, and records the relationship between the two as an open
  question rather than merging them. Which one a given STX4 genotype produces is exactly the
  kind of question a dose-dependent allelic series raises, and nobody has tested it.

  OMIM flags the gene-phenotype relationship as provisional: NCBI mim2gene_medgen carries
  the `question` comment on OMIM:620745, its marker for a gene-map phenotype entered with a
  leading question mark. That is consistent with the evidence base - one family, however well
  it segregates, plus non-human functional support.
disease_term:
  preferred_term: autosomal recessive nonsyndromic hearing loss 123
  term:
    id: MONDO:0958277
    label: hearing loss, autosomal recessive 123
parents:
- Autosomal Recessive Nonsyndromic Hearing Loss
references:
- reference: PMID:36355422
  title: "Syntaxin 4 is essential for hearing in human and zebrafish."
- reference: PMID:35599850
  title: "Stx4 is required to regulate cardiomyocyte Ca(2+) handling during vertebrate cardiac development."
inheritance:
- name: Autosomal recessive
  description: >-
    One large consanguineous Pakistani family with eight affected individuals, all homozygous
    for the STX4 splice-region variant, which segregated with hearing impairment at a
    two-point LOD of 5.9. No heterozygote is reported as affected. The syndromic STX4 patient
    described separately is also homozygous, for a missense allele.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
    explanation: >-
      Homozygosity, the segregation result and its statistical strength in one sentence. A
      two-point LOD of 5.9 in a single pedigree is well above the conventional threshold of
      3.3.
pathophysiology:
- name: STX4 Biallelic Loss of Function
  biological_scale: MOLECULAR
  description: >-
    Homozygosity for a splice-region variant, c.232+6T>C, which causes exon skipping and a
    consequent frameshift. A frameshift early in the transcript predicts a truncated product
    or nonsense-mediated decay, so this is treated as a loss-of-function allele; that
    prediction has not been confirmed by measuring STX4 protein in patient cells.

    The missense allele p.Arg240Trp reported in the syndromic STX4 patients is a different
    kind of change, and its zebrafish equivalent was shown to be hypomorphic rather than
    null. The two alleles are noted together because the contrast is the most likely
    explanation for the two different clinical pictures, but they are not pooled: only the
    splice allele belongs to DFNB123.
  genes:
  - preferred_term: STX4
    term:
      id: hgnc:11439
      label: STX4
  genetic_context:
    genes:
    - preferred_term: STX4
      term:
        id: hgnc:11439
        label: STX4
    allele_type: splice region variant causing exon skipping and frameshift
    variant_origin: GERMLINE
    zygosity: HOMOZYGOUS
    functional_impact_category: LOSS_OF_FUNCTION
    notes: >-
      LOSS_OF_FUNCTION is recorded as the consequence class of the DFNB123 allele, on the
      strength of the reported exon skipping and frameshift. It is a prediction from the
      splicing result, not a measurement of residual STX4 activity, and no patient-derived
      material has been assayed.
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
    explanation: The allele, its molecular consequence, and the evidence that it is the cause.
  - reference: PMID:35599850
    reference_title: "Stx4 is required to regulate cardiomyocyte Ca(2+) handling during vertebrate cardiac development."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: "Transgenic overexpression of zebrafish Stx4R241W, analogous to the first patient's STX4R240W variant, indicated that the variant is hypomorphic."
    explanation: >-
      Cited for the contrast rather than for DFNB123 itself: the syndromic patients carry a
      partial-function allele, which is why a frameshift allele producing a different
      phenotype is not a contradiction. INDIRECT because it is a statement about a different
      variant in a different species.
  downstream:
  - target: Failure of SNARE-Mediated Membrane Fusion
    causal_link_type: DIRECT
- name: Failure of SNARE-Mediated Membrane Fusion
  biological_scale: MOLECULAR
  description: >-
    Syntaxin-4 is a target-SNARE: it sits in the plasma membrane and pairs with vesicle
    SNAREs to drive the fusion step of vesicle delivery and recycling. Losing it removes one
    half of that pairing, so vesicles reach the membrane but do not dock and fuse normally.
    The direct demonstration of that failure is in zebrafish heart, where Vamp2-positive
    vesicles show reduced docking at the cardiomyocyte sarcolemma in stx4 mutants. Nothing
    equivalent has been imaged in a hair cell, so the fusion defect is established for the
    protein and assumed for the ear.
  molecular_functions:
  - preferred_term: SNARE binding
    modifier: DECREASED
    term:
      id: GO:0000149
      label: SNARE binding
  biological_processes:
  - preferred_term: vesicle fusion at the plasma membrane
    modifier: DECREASED
    term:
      id: GO:0006906
      label: vesicle fusion
  - preferred_term: vesicle-mediated transport
    modifier: DECREASED
    term:
      id: GO:0016192
      label: vesicle-mediated transport
  cellular_components:
  - preferred_term: plasma membrane
    term:
      id: GO:0005886
      label: plasma membrane
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "STX4, a member of the syntaxin family, is a component of the SNARE machinery involved in several vesicle transport and recycling pathways."
    explanation: >-
      The molecular identity of the gene product. BACKGROUND because it restates established
      cell biology rather than reporting this paper's own result.
  - reference: PMID:35599850
    reference_title: "Stx4 is required to regulate cardiomyocyte Ca(2+) handling during vertebrate cardiac development."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: "Imaging of Vamp2+ vesicles within stx4 mutant zebrafish hearts showed reduced docking to the cardiomyocyte sarcolemma."
    explanation: >-
      The one direct measurement of the fusion defect caused by loss of Stx4 in a vertebrate.
      INDIRECT because it was made in cardiomyocytes, not hair cells; it establishes that the
      protein is required for docking, not that this is what fails in the cochlea.
  downstream:
  - target: Loss of Syntaxin-4 from the Hair Cell Membrane and Stereocilia
    causal_link_type: DIRECT
- name: Loss of Syntaxin-4 from the Hair Cell Membrane and Stereocilia
  biological_scale: CELLULAR
  description: >-
    The reason a general trafficking protein produces isolated deafness is where it is. The
    murine orthologue Stx4a is highly and widely expressed through the developing and adult
    inner ear, and immunofluorescence puts STX4A in three places in both inner and outer hair
    cells: the cell body, the plasma membrane, and the stereocilia. Stereocilial localisation
    is the finding that connects a fusion protein to mechanotransduction, because that is
    where the transduction machinery sits.

    Which of the three pools carries the disease-relevant function is not known, and no
    patient hair cell has been examined.
  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
  cellular_components:
  - preferred_term: stereocilium
    term:
      id: GO:0032420
      label: stereocilium
  locations:
  - preferred_term: spiral organ of the cochlea
    term:
      id: UBERON:0002227
      label: spiral organ of cochlea
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In silico analysis showed that murine orthologue Stx4a is highly and widespread expressed in the developing and adult inner ear."
    explanation: >-
      The expression argument. Graded MODEL_ORGANISM because the data are mouse, and worth
      noting that the analysis was in silico over existing expression resources rather than a
      new measurement.
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Immunofluorescent imaging revealed localization of STX4A in the cell body, cell membrane and stereocilia of inner and outer hair cells."
    explanation: >-
      The subcellular localisation, including the stereocilial pool that links the protein to
      transduction.
  downstream:
  - target: Hair Cell Mechanotransduction Failure
    causal_link_type: DIRECT
  - target: Disturbed Inner Ear Development
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Hair Cell Mechanotransduction Failure
  biological_scale: CELLULAR
  description: >-
    Knocking down stx4 in zebrafish disrupts mechanotransduction in neuromast hair cells,
    measured by FM1-43 uptake - the dye enters hair cells through open transduction channels,
    so reduced uptake reports that the channels are not passing current. The behavioural
    counterpart in the same animals is an abnormal startle response, which is the whole-animal
    readout of hair cell function in a larval fish.

    This is the node that carries the entity's mechanistic claim, and it is entirely
    non-mammalian. Neuromast hair cells are lateral-line cells, not cochlear ones, and no
    mammalian Stx4 hearing model has been reported. The cell type bound here is the human
    cochlear inner hair cell, because that is what the node is about; the measurement behind
    it was made in a zebrafish neuromast hair cell, and the gap between the two is the subject
    of this entry's human-model-mismatch discussion rather than something the binding hides.

    The bound process is the detection step rather than the perception it serves. An earlier
    version bound GO:0050954 sensory perception of mechanical stimulus and GO:0007605 sensory
    perception of sound, both of which are organism-level processes sitting on a node tagged
    CELLULAR. GO:0050910 is the cellular transduction event that FM1-43 uptake actually
    reports, so it matches both the scale tag and the assay.
  cell_types:
  - preferred_term: cochlear inner hair cell
    term:
      id: CL:0000589
      label: cochlear inner hair cell
  biological_processes:
  - preferred_term: hair cell mechanotransduction
    modifier: DECREASED
    term:
      id: GO:0050910
      label: detection of mechanical stimulus involved in sensory perception of sound
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "a morpholino-based knockdown of stx4 in zebrafish showed an abnormal startle response, morphological and developmental defects, and a disrupted mechanotransduction function in neuromast hair cells measured via FM1-43 uptake"
    explanation: >-
      The functional result, its readout, and the behavioural correlate, all from the
      morpholino knockdown.
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Our findings indicate that STX4 dysfunction leads to HI in humans and zebrafish and supports the evolutionary conserved role of STX4 in inner ear development and hair cell functioning."
    explanation: >-
      The conclusion the paper draws, which names both strands of the mechanism this entry
      curates: development and hair cell function.
  downstream:
  - target: Bilateral Severe-to-Profound Hearing Impairment
    causal_link_type: DIRECT
- name: Disturbed Inner Ear Development
  biological_scale: TISSUE
  description: >-
    The second strand of the mechanism, and the weaker one. Stx4a is expressed in the
    developing as well as the adult inner ear, morpholino knockdown produces developmental
    defects in zebrafish, and CRISPR-generated stx4 mutant fish show frank otic vesicle
    dysgenesis. Whether anything corresponding happens in a human cochlea is unknown: no
    imaging of the inner ear is reported for any DFNB123 patient, and severe-to-profound loss
    with no other feature is compatible with a purely functional lesion.
  biological_processes:
  - preferred_term: inner ear development
    modifier: DECREASED
    term:
      id: GO:0048839
      label: inner ear development
  evidence:
  - reference: PMID:35599850
    reference_title: "Stx4 is required to regulate cardiomyocyte Ca(2+) handling during vertebrate cardiac development."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: "CRISPR/Cas9-generated stx4 mutant zebrafish exhibited defects reminiscent of these patients' clinical presentations, including linearized hearts, bradycardia, otic vesicle dysgenesis, neuronal atrophy, and touch insensitivity by 3 days post fertilization."
    explanation: >-
      The otic vesicle phenotype in a genetic null fish, which is the strongest evidence that
      loss of Stx4 disturbs ear development rather than only ear function. INDIRECT because
      it comes from the syndromic-STX4 paper and from a fish, so it is two steps from the
      DFNB123 claim.
  downstream:
  - target: Bilateral Severe-to-Profound Hearing Impairment
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
phenotypes:
- name: Bilateral Severe-to-Profound Hearing Impairment
  category: Ear
  description: >-
    The only feature reported in the DFNB123 family, in all eight affected individuals. The
    source describes it as bilateral and severe-to-profound. It does not say sensorineural,
    which is why the bound term is a severity term rather than a sensorineural one; the
    sensorineural character of STX4-related hearing loss is documented in the separately
    reported syndromic patient rather than in this family.
  frequency: OBLIGATE
  phenotype_term:
    preferred_term: Bilateral severe-to-profound hearing impairment
    term:
      id: HP:0012714
      label: Severe hearing impairment
  notes: >-
    OBLIGATE with a denominator of eight affected individuals in one family. A nonsyndromic
    deafness entity is ascertained through its hearing loss, so the band carries no
    information about penetrance.

    On the binding being narrower than the claim: HPO splits the severity axis into
    HP:0012714 Severe hearing impairment and HP:0012715 Profound hearing impairment, with no
    combined severe-to-profound term and no bilateral term that leaves the sensorineural
    question open. Checked against the live ontology on 2026-09-17. The entry therefore binds
    the lower bound of the reported range and carries the full range in preferred_term. A
    second phenotype for the profound end is not curated because no per-individual audiogram
    is reported, so it would have no denominator and could not be given a frequency band. The
    deep-research report committed with this entry independently suggests HP:0000407,
    HP:0008619, HP:0012714 and HP:0012715 for this phenotype, which corroborates the choice
    without resolving the range problem.

    Two details are deliberately absent because the source does not supply them. Age of onset
    is not stated in the abstract, so no onset phenotype is curated even though OMIM
    summarises the entity as beginning within the first decade - and the deep-research report
    reaches the same conclusion from the full text, noting that the publication describes
    congenital hearing impairment at study level while the individual data do not establish
    onset in every relative. Audiometric configuration and laterality asymmetry are likewise
    not reported in the abstract.
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we used exome sequencing to investigate a large consanguineous Pakistani family with eight affected individuals showing bilateral severe-to-profound HI"
    explanation: >-
      The phenotype, its laterality, its severity range, and the number of affected
      individuals it was observed in.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    No prevalence estimate exists. One family has been reported, in one 2023 paper. No second
    family carrying a nonsyndromic STX4 genotype has been published, so there is no
    denominator of any kind and no rate is recorded.
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we used exome sequencing to investigate a large consanguineous Pakistani family with eight affected individuals showing bilateral severe-to-profound HI"
    explanation: The whole published case series, which is a single pedigree.
progression:
- phase: Unknown
  notes: >-
    Nothing is published. The report gives no age of onset, no serial audiometry and no
    follow-up, so whether DFNB123 is stable or progressive is unknown. This phase exists to
    record that absence rather than to describe a course, and nothing is imported from the
    zebrafish, whose developmental time course would not be a human natural history.
genetic:
- name: STX4
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: STX4
    term:
      id: hgnc:11439
      label: STX4
  features: >-
    STX4 at 16p11.2 encodes syntaxin-4, a plasma-membrane t-SNARE. The DFNB123 allele is a
    homozygous splice region variant, c.232+6T>C, causing exon skipping and a frameshift. A
    separate report describes a homozygous missense allele, p.Arg240Trp, in a patient with a
    syndromic presentation, and a second patient with severe pleiotropic abnormalities and
    perinatal lethality.
  notes: >-
    OMIM records the gene-phenotype relationship as provisional. NCBI mim2gene_medgen maps
    OMIM:620745 to GeneID 6810 with source GeneMap and the comment `question`, the marker for
    an OMIM gene-map phenotype carrying a leading question mark. That grading fits the
    evidence: the segregation within the one reported family is strong, but a single pedigree
    plus zebrafish and expression data is not multi-family replication.
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
    explanation: The causative allele and the segregation evidence for it.
  - reference: PMID:35599850
    reference_title: "Stx4 is required to regulate cardiomyocyte Ca(2+) handling during vertebrate cardiac development."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A patient with a homozygous R240W missense variant displayed biventricular dilated cardiomyopathy, ectopy, and runs of non-sustained ventricular tachycardia, sensorineural hearing loss, global developmental delay, and hypotonia, while a second patient displayed severe pleiotropic abnormalities and perinatal lethality."
    explanation: >-
      The other end of the STX4 phenotypic spectrum, recorded here so that a curator reading
      only the DFNB123 entry is not surprised by a cardiomyopathy report. These patients are
      not DFNB123 and their features are not curated as phenotypes of it.
diagnosis:
- name: STX4 sequencing in unexplained bilateral severe-to-profound hearing impairment
  description: >-
    The family was solved by exome sequencing performed for undiagnosed recessive hearing
    impairment; STX4 was not a hearing-loss gene when the work was done. The practical
    consequence is that an exome or panel report predating 2023 will not have considered
    STX4, and that a splice-region variant six bases into the intron is the kind of change a
    filtering pipeline tuned to canonical splice sites can drop.
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we used exome sequencing to investigate a large consanguineous Pakistani family with eight affected individuals showing bilateral severe-to-profound HI"
    explanation: The test that made the diagnosis, and the clinical setting it was used in.
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "Congenital hearing impairment (HI) is a genetically highly heterogeneous disorder in which prompt recognition and intervention are crucial to optimize outcomes."
    explanation: >-
      The argument for testing at all. BACKGROUND because it is the paper's opening framing
      of the field, not a finding about this family, and it is quoted only for the
      heterogeneity and early-intervention points rather than as a statement that this family
      had congenital onset.
treatments:
- name: Genetic Counselling and Cascade Testing
  description: >-
    Counselling for a recessive condition in a consanguineous family with eight affected
    members, where the sibling recurrence risk is 25 percent and carrier frequency within the
    kindred is high. Counselling does not act on the mechanism; it is curated because it is
    the only intervention the genotype itself indicates.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
    explanation: >-
      The segregating homozygous allele in a consanguineous pedigree, which is what carrier
      testing and recurrence counselling act on.
  notes: >-
    No treatment is reported for any member of the DFNB123 family - no hearing aid, no
    cochlear implant, no audiological follow-up beyond the diagnostic assessment. Cochlear
    implantation is standard care for bilateral severe-to-profound loss and would look right
    here, but attributing it to these patients would import an indication recorded only in
    other people. The one thing the source does say about intervention is general: that
    prompt recognition and intervention are crucial to optimize outcomes in congenital
    hearing impairment, which is quoted under diagnosis rather than as a treatment.

    The deep-research sweep committed with this entry reached the same position independently
    and sharpened the reason. It found no DFNB123-specific drug, gene, RNA or cell therapy and
    no relevant clinical trial, and it located exactly one cochlear-implant datapoint in the
    STX4 literature: the homozygous p.Arg240Trp patient, implanted at age six with improved
    communication. That patient has the syndromic presentation, not DFNB123, so the one
    implantation outcome on record belongs to the other end of the allelic spectrum. Curating
    implantation here on the strength of it would attach a different genotype's outcome to
    this entity.
animal_models:
- name: stx4 morpholino knockdown zebrafish
  species: Zebrafish
  genotype: transient morpholino knockdown of stx4
  publication: PMID:36355422
  description: >-
    The functional model behind DFNB123. Knockdown larvae have an abnormal startle response,
    morphological and developmental defects, and reduced FM1-43 uptake in neuromast hair
    cells, which reports loss of mechanotransduction.
  modeled_mechanisms:
  - target: Hair Cell Mechanotransduction Failure
    relationship: RECAPITULATES
    fidelity: LOW
    model_scale: CELLULAR
    description: >-
      FM1-43 uptake in neuromast hair cells is a direct cellular measurement of
      mechanotransduction, at the scale of the node.
    limitations: >-
      Three separate gaps sit between this model and the human disease. Neuromast hair cells
      belong to the lateral line, not the cochlea, and a fish has no cochlea at all. The
      knockdown is a transient morpholino rather than a genetic null, so residual protein and
      off-target effects are not excluded. And the knockdown removes stx4 from the whole
      embryo, so a hair cell defect is not shown to be cell-autonomous. Fidelity is graded
      LOW for those reasons and not because the result is weak.
    readouts:
    - name: FM1-43 uptake in neuromast hair cells
      target: Hair Cell Mechanotransduction Failure
      direction: DECREASED
      interpretation: >-
        The dye enters hair cells through open mechanotransduction channels, so reduced
        uptake reports that transduction is not working.
      evidence:
      - reference: PMID:36355422
        reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "a disrupted mechanotransduction function in neuromast hair cells measured via FM1-43 uptake"
        explanation: The measurement and the assay used to make it.
    - name: Startle response
      target: Hair Cell Mechanotransduction Failure
      direction: ALTERED
      interpretation: >-
        The whole-animal behavioural correlate of hair cell function in a larval fish.
      evidence:
      - reference: PMID:36355422
        reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "a morpholino-based knockdown of stx4 in zebrafish showed an abnormal startle response"
        explanation: The behavioural readout in the knockdown larvae.
    evidence:
    - reference: PMID:36355422
      reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Our findings indicate that STX4 dysfunction leads to HI in humans and zebrafish and supports the evolutionary conserved role of STX4 in inner ear development and hair cell functioning."
      explanation: >-
        The authors' own claim that the fish result is informative for the human phenotype,
        which is what this link records.
- name: stx4 CRISPR mutant zebrafish
  species: Zebrafish
  genotype: CRISPR/Cas9-generated stx4 mutant
  publication: PMID:35599850
  description: >-
    A genetic null fish made for the cardiac phenotype, which also has otic vesicle
    dysgenesis and touch insensitivity. It is included here because it is the only genetic
    (as opposed to morpholino) loss-of-function animal in which ear phenotypes have been
    looked at.
  modeled_mechanisms:
  - target: Disturbed Inner Ear Development
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    model_scale: TISSUE
    description: >-
      Otic vesicle dysgenesis is a direct tissue-level observation of disturbed ear
      development.
    limitations: >-
      The otic vesicle is the embryonic precursor of the whole inner ear in a fish and is not
      a cochlea; no human DFNB123 patient has had inner ear imaging, so there is no human
      counterpart to compare with. The model was also made and characterised for a cardiac
      phenotype that DFNB123 patients do not have, which is itself the open question this
      entry files as a discussion.
    evidence:
    - reference: PMID:35599850
      reference_title: "Stx4 is required to regulate cardiomyocyte Ca(2+) handling during vertebrate cardiac development."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "CRISPR/Cas9-generated stx4 mutant zebrafish exhibited defects reminiscent of these patients' clinical presentations, including linearized hearts, bradycardia, otic vesicle dysgenesis, neuronal atrophy, and touch insensitivity by 3 days post fertilization."
      explanation: The ear phenotype of the genetic null, alongside the cardiac one.
  notes: >-
    The cardiac phenotype of this model - linearized hearts, bradycardia, reduced vesicle
    docking at the sarcolemma, reduced L-type calcium channel modulation - is deliberately
    not linked to any node in this entry. DFNB123 patients have no reported cardiac
    phenotype, and importing one would assert a feature the family does not have.
discussions:
- discussion_id: dfnb123_nonsyndromic_versus_syndromic_stx4
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - "pathophysiology#STX4 Biallelic Loss of Function"
  - "genetic#STX4"
  prompt: >-
    Why does one biallelic STX4 genotype give isolated deafness while another gives dilated
    cardiomyopathy, developmental delay and, in one case, perinatal lethality?
  rationale: >-
    Two groups have reported biallelic STX4 disease and the pictures do not overlap. The
    DFNB123 family, homozygous for a splice allele causing exon skipping and a frameshift,
    has hearing impairment and nothing else in eight affected members. The separately
    reported patients, one homozygous for the missense allele p.Arg240Trp, have
    cardiomyopathy with ventricular ectopy, sensorineural hearing loss, developmental delay
    and hypotonia, or perinatal lethality with severe pleiotropic abnormalities. The
    zebrafish null has both an ear and a heart phenotype, which is what one would expect of
    a gene used everywhere.

    The obvious reading - a dose-dependent allelic series - is complicated by its direction.
    The zebrafish equivalent of the missense allele is hypomorphic, so the patients with the
    milder allele have the more severe, multi-system disease, while the family with a
    frameshift has isolated deafness. That is the wrong way round for a simple dosage model,
    and it is the reason this is filed as an open question rather than written into the entry
    as an allelic series. Residual protein from the skipped-exon transcript, modifier
    background, and ascertainment (a deafness study would not look for subclinical
    cardiomyopathy) are all live alternatives, and none has been tested.

    It matters clinically: if the two are one disease, DFNB123 patients need cardiac
    surveillance.

    One partial answer exists and is recorded here with its provenance, because it cannot be
    given a verified snippet. The deep-research report committed with this entry reads the
    full text of the defining paper and states that electrocardiograms were normal in two
    tested affected relatives of the DFNB123 family, and that no consistent vestibular,
    facial, neurologic or cardiac abnormality was found. The cached reference for
    PMID:36355422 is abstract-only, and that sentence is not in the abstract, so no evidence
    item can carry it. Two normal ECGs in eight affected individuals is in any case a weak
    negative - it is not echocardiography, and cardiomyopathy in the syndromic patient was
    dilated rather than electrical - so it narrows the question rather than closing it.
  proposed_experiments:
  - experiment_id: dfnb123_stx4_allele_series_and_cardiac_surveillance
    name: Transcript quantification of the DFNB123 allele, plus cardiac assessment of the family
    description: >-
      Measure STX4 transcript and protein from patient-derived cells homozygous for
      c.232+6T>C, to establish whether the skipped-exon allele is a true null or leaves
      residual product; and echocardiography with electrocardiography in the affected family
      members, reported whether normal or abnormal.
    readouts:
    - name: Residual STX4 protein in patient cells
      target: "pathophysiology#STX4 Biallelic Loss of Function"
      direction: DECREASED
      interpretation: >-
        A true null in patients with isolated deafness would refute the simple dosage model
        outright and point at tissue-specific compensation or modifiers.
    - name: Left ventricular ejection fraction in DFNB123 family members
      target: "phenotypes#Bilateral Severe-to-Profound Hearing Impairment"
      interpretation: >-
        Subclinical cardiomyopathy in the deafness family would unify the two reports and
        make cardiac surveillance part of managing DFNB123. A normal result across eight
        affected members would establish that the phenotypes really are separable.
- discussion_id: dfnb123_no_mammalian_ear_model
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - "pathophysiology#Hair Cell Mechanotransduction Failure"
  prompt: >-
    Does loss of Stx4 impair hearing in a mammal, and does it do so through the cochlear hair
    cells where STX4A is localised?
  rationale: >-
    The mechanistic claim in this entry rests on a zebrafish morpholino knockdown assayed in
    neuromast hair cells. Those are lateral-line cells; a fish has no cochlea, no
    endocochlear potential and no outer hair cell amplifier. The mammalian evidence is
    expression and immunolocalisation only - Stx4a is present through the mouse inner ear and
    STX4A sits in the cell body, membrane and stereocilia of inner and outer hair cells - and
    expression is not function. No mouse with an inner ear Stx4 deletion has been reported,
    and a constitutive knockout would be confounded by the gene's roles elsewhere.

    Filed as a human-model mismatch rather than a knowledge gap because the experiment was
    done, in a model whose fidelity to the human cochlea is the open question, rather than
    not done at all.
  proposed_experiments:
  - experiment_id: dfnb123_hair_cell_conditional_stx4_mouse
    name: Hair-cell-conditional Stx4 knockout mouse
    description: >-
      A floxed Stx4 allele crossed to a hair-cell Cre, with auditory brainstem response and
      distortion-product otoacoustic emission thresholds, endocochlear potential measurement,
      and hair bundle morphology, compared against littermate controls.
    readouts:
    - name: Auditory brainstem response threshold
      target: "pathophysiology#Hair Cell Mechanotransduction Failure"
      direction: INCREASED
      interpretation: >-
        Raised thresholds in a hair-cell-restricted knockout would establish both that Stx4
        is required for mammalian hearing and that it acts in the hair cell, which is the
        step the fish data cannot supply.
    - name: Endocochlear potential
      target: "pathophysiology#Hair Cell Mechanotransduction Failure"
      interpretation: >-
        A normal endocochlear potential alongside raised thresholds would separate this
        mechanism from the lateral-wall deafness genes and confirm the lesion is in the hair
        cell itself.
external_assertions:
- name: OMIM deafness, autosomal recessive 123 record
  source: OMIM
  assertion_type: disease_record
  external_id: OMIM:620745
  url: https://omim.org/entry/620745
  description: >-
    The OMIM phenotype record under which DFNB123 was designated, based on the Pakistani
    family reported by Schrauwen et al. Recorded here rather than under mappings because the
    DiseaseMappings class carries only ICD-10-CM, ICD-11, MONDO and NCIT slots. NCBI
    mim2gene_medgen maps this MIM number to GeneID 6810 (STX4) with source GeneMap and the
    comment `question`, marking the gene-phenotype relationship as provisional in OMIM.
  evidence:
  - reference: PMID:36355422
    reference_title: "Syntaxin 4 is essential for hearing in human and zebrafish."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9)."
    explanation: The gene-disease finding on which the OMIM designation rests.
notes: >-
  Scope decision: curated as a DISEASE. One gene, one lesion class, one clinical picture in
  one large pedigree. There are no member diseases to unite and this is not a subtype of any
  curated entry. Its MONDO parent, MONDO:0019588 hearing loss, autosomal recessive, is an
  ontology grouping of dozens of unrelated DFNB loci and is not a dismech entry. The stub is
  deleted by this change.

  Identity resolution, since the stub and MONDO both record no causal gene: MONDO:0958277
  cross-references OMIM:620745, and NCBI mim2gene_medgen maps OMIM:620745 to GeneID 6810,
  which is STX4 at 16p11.2. That is the opposite outcome from the DFNB46 ruling in #11978,
  where the same lookup returned GeneID `-` and the concept was placed out of scope as a
  mapped locus. A search of `kb/` for STX4 and DFNB123 before writing found no existing
  coverage under any name.

  Evidence balance, stated rather than smoothed. The clinical picture is one family. The
  mechanism is expression data in mouse, immunolocalisation in mouse, and function in
  zebrafish; there is no mammalian Stx4 hearing model and no human cochlear material. Every
  node below the gene is graded MODEL_ORGANISM and the two weakest links - a cardiomyocyte
  docking assay standing in for a hair cell one, and a lateral-line neuromast standing in for
  a cochlea - are marked INDIRECT and spelled out in the node descriptions and in the model
  limitations rather than only in the grading.

  The entry deliberately curates a single phenotype. The source reports no onset age, no
  audiometric configuration and no follow-up, and the richer phenotype available for STX4 in
  the literature belongs to the syndromic patients, who are a different presentation and are
  recorded as such under genetic and in a discussion rather than folded in here.

  Deep-research sweep. A falcon run is committed with this entry
  (research/Autosomal_Recessive_Nonsyndromic_Hearing_Loss_123-deep-research-falcon.md), and
  what it found is the answer to whether this entry is thin because the literature stops or
  because the literature was not swept. It stops. The report's entire evidence base is the
  same two publications the entry already cites - reference validation resolved 2 of 2
  citations with no unresolved or confabulated references - and it surfaces no third paper,
  no clinical trial, and no DFNB123-specific therapy. It reaches the entry's own conclusions
  independently on the three points where restraint was exercised: that congenital onset
  should be curated with caution because individual onset ages are not established, that the
  cochlear-implant datapoint in the STX4 literature belongs to the syndromic p.Arg240Trp
  patient rather than to DFNB123, and that cardiac and neurologic involvement belongs to the
  wider biallelic STX4 spectrum rather than to this entity.

  The report was run with the entry's name temporarily set to "DFNB123 STX4-related autosomal
  recessive nonsyndromic hearing loss" so the query named the gene, which the numbered label
  does not. Identity was confirmed manually rather than by the gene check: just preflight-dr
  returns SKIP because MONDO records no causal gene for MONDO:0958277 and the check cannot
  discriminate, so the report was counted directly - STX4 appears 52 times against 2 for the
  next most frequent symbol, DFNB123 appears 36 times, and the report quotes the same
  c.232+6T>C allele and LOD of 5.9 as the cached abstract. The run's own term validation
  errored on an ontology-service timeout and wrote no Term Validation section, so no CURIE
  from the report was taken on its authority; every binding in this entry was resolved against
  the ontology separately.

  The report does carry facts from the full text that this entry cannot use - eight affected
  and five unaffected relatives examined, audiometry at 250 to 8000 Hz in relatives aged 10 to
  25, a minigene assay showing exon 3 skipping, a gnomAD v2 allele frequency of 7.98e-06, a
  ClinVar submission, normal electrocardiograms in two tested relatives, absence of vestibular
  dysfunction. The cached reference for PMID:36355422 is abstract-only from both the PubMed
  and the DOI route, so none of those can carry a verified snippet and none is curated as
  evidence. Where one of them bears on an open question it is recorded in prose with that
  provenance stated.

  The entry name uses the repository's Autosomal Recessive Nonsyndromic Hearing Loss NNN
  convention, which the disease_term preferred_term follows. The bound MONDO label is
  different - "hearing loss, autosomal recessive 123" - because that is what MONDO calls the
  term and term labels are copied from the ontology, not composed. MONDO has no
  "autosomal recessive nonsyndromic hearing loss 123" term.
📚

References & Deep Research

References

2
PMID:36355422
Syntaxin 4 is essential for hearing in human and zebrafish.
No top-level findings curated for this source.
PMID:35599850
Stx4 is required to regulate cardiomyocyte Ca(2+) handling during vertebrate cardiac development.
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 (2)

Record notes

Scope decision: curated as a DISEASE. One gene, one lesion class, one clinical picture in one large pedigree. There are no member diseases to unite and this is not a subtype of any curated entry. Its MONDO parent, MONDO:0019588 hearing loss, autosomal recessive, is an ontology grouping of dozens of unrelated DFNB loci and is not a dismech entry. The stub is deleted by this change. Identity resolution, since the stub and MONDO both record no causal gene: MONDO:0958277 cross-references OMIM:620745, and NCBI mim2gene_medgen maps OMIM:620745 to GeneID 6810, which is STX4 at 16p11.2. That is the opposite outcome from the DFNB46 ruling in #11978, where the same lookup returned GeneID `-` and the concept was placed out of scope as a mapped locus. A search of `kb/` for STX4 and DFNB123 before writing found no existing coverage under any name. Evidence balance, stated rather than smoothed. The clinical picture is one family. The mechanism is expression data in mouse, immunolocalisation in mouse, and function in zebrafish; there is no mammalian Stx4 hearing model and no human cochlear material. Every node below the gene is graded MODEL_ORGANISM and the two weakest links - a cardiomyocyte docking assay standing in for a hair cell one, and a lateral-line neuromast standing in for a cochlea - are marked INDIRECT and spelled out in the node descriptions and in the model limitations rather than only in the grading. The entry deliberately curates a single phenotype. The source reports no onset age, no audiometric configuration and no follow-up, and the richer phenotype available for STX4 in the literature belongs to the syndromic patients, who are a different presentation and are recorded as such under genetic and in a discussion rather than folded in here. Deep-research sweep. A falcon run is committed with this entry (research/Autosomal_Recessive_Nonsyndromic_Hearing_Loss_123-deep-research-falcon.md), and what it found is the answer to whether this entry is thin because the literature stops or because the literature was not swept. It stops. The report's entire evidence base is the same two publications the entry already cites - reference validation resolved 2 of 2 citations with no unresolved or confabulated references - and it surfaces no third paper, no clinical trial, and no DFNB123-specific therapy. It reaches the entry's own conclusions independently on the three points where restraint was exercised: that congenital onset should be curated with caution because individual onset ages are not established, that the cochlear-implant datapoint in the STX4 literature belongs to the syndromic p.Arg240Trp patient rather than to DFNB123, and that cardiac and neurologic involvement belongs to the wider biallelic STX4 spectrum rather than to this entity. The report was run with the entry's name temporarily set to "DFNB123 STX4-related autosomal recessive nonsyndromic hearing loss" so the query named the gene, which the numbered label does not. Identity was confirmed manually rather than by the gene check: just preflight-dr returns SKIP because MONDO records no causal gene for MONDO:0958277 and the check cannot discriminate, so the report was counted directly - STX4 appears 52 times against 2 for the next most frequent symbol, DFNB123 appears 36 times, and the report quotes the same c.232+6T>C allele and LOD of 5.9 as the cached abstract. The run's own term validation errored on an ontology-service timeout and wrote no Term Validation section, so no CURIE from the report was taken on its authority; every binding in this entry was resolved against the ontology separately. The report does carry facts from the full text that this entry cannot use - eight affected and five unaffected relatives examined, audiometry at 250 to 8000 Hz in relatives aged 10 to 25, a minigene assay showing exon 3 skipping, a gnomAD v2 allele frequency of 7.98e-06, a ClinVar submission, normal electrocardiograms in two tested relatives, absence of vestibular dysfunction. The cached reference for PMID:36355422 is abstract-only from both the PubMed and the DOI route, so none of those can carry a verified snippet and none is curated as evidence. Where one of them bears on an open question it is recorded in prose with that provenance stated. The entry name uses the repository's Autosomal Recessive Nonsyndromic Hearing Loss NNN convention, which the disease_term preferred_term follows. The bound MONDO label is different - "hearing loss, autosomal recessive 123" - because that is what MONDO calls the term and term labels are copied from the ontology, not composed. MONDO has no "autosomal recessive nonsyndromic hearing loss 123" term.

Review round 1: add the falcon deep-research artifact, rebind the mechanotransduction process · 2026-09-17T18:22:06Z · View source

Addressed the blocking finding and three of the four suggestions in one push. (1) Blocker: no deep-research artifact. Ran falcon (13 minutes, 6 citations) with the entry name temporarily set to 'DFNB123 STX4-related autosomal recessive nonsyndromic hearing loss' so the query named the gene; report, citations sidecar and one artifact are committed, along with the two DOI reference-cache files its citation validation wrote. The report's evidence base is the same two publications the entry already cites and it surfaces no third; linkml-reference-validator resolved 2 of 2 citations with none unresolved. just preflight-dr returns SKIP because MONDO records no causal gene, so identity was confirmed by hand: STX4 52 mentions against 2 for the next symbol, DFNB123 36 mentions, same c.232+6T>C allele and LOD 5.9 as the cached abstract. The run's term validation errored on an ontology-service timeout and wrote no Term Validation section, so no CURIE was taken from it. (2) Rebound the mechanotransduction node from GO:0050954 and GO:0007605, both organism-level, to GO:0050910 detection of mechanical stimulus involved in sensory perception of sound, which matches the node's CELLULAR scale tag and the FM1-43 assay. (3) Recorded the HPO severity lookup in the phenotype notes: HP:0012714 and HP:0012715 are separate terms with no severe-to-profound or bilaterality-unqualified option, so the lower bound is bound deliberately and a second phenotype for the profound end would have no denominator. (4) Sharpened the node description on the cell-type-versus-model-tissue point. Also recorded, with provenance, two things the report reads from the full text that cannot carry a verified snippet because the cache is abstract-only from both the PubMed and the DOI route: normal ECGs in two tested relatives (partial answer to the syndromic knowledge gap) and the cochlear-implant datapoint belonging to the syndromic p.Arg240Trp patient (which sharpens the treatment scoping rationale). Revalidated: just validate clean, 22/22 snippets verified, check-entity-refs, check-duplicate-keys, check-causal-targets, check-qualifier-terms, check-folded-hyphens, check-enum-values all OK; no cache rows changed.

Falcon ▸
Disease Characteristics Research Template
Edison Scientific Literature 6 citations 2026-09-17T11:12:16.436496

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: DFNB123 STX4-related autosomal recessive nonsyndromic hearing loss
  • MONDO ID: MONDO:0958277 (if available)
  • Category: Mendelian

Research Objectives

Please provide a comprehensive research report on DFNB123 STX4-related autosomal recessive nonsyndromic hearing loss 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

DFNB123: STX4-related autosomal-recessive nonsyndromic hearing loss

Executive summary and evidence scope

DFNB123 is an ultra-rare Mendelian hearing disorder attributed to biallelic loss of STX4, encoding syntaxin-4, a plasma-membrane target-SNARE. The defining evidence is one large consanguineous Pakistani pedigree containing eight affected relatives with bilateral severe-to-profound or profound hearing impairment and homozygous STX4 NM_004604.5:c.232+6T>C. Segregation was strong (two-point LOD 5.9), and a minigene assay demonstrated exon-3 skipping and a frameshift predicted to cause nonsense-mediated decay. Mouse inner-ear localization and zebrafish knockdown studies provide complementary biological support. Because only one specifically nonsyndromic family has been published, estimates of prevalence, penetrance, natural history, and genotype–phenotype relationships remain provisional. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 1-2, schrauwen2023syntaxin4is pages 3-6)

The defining paper is Schrauwen et al., “Syntaxin 4 is essential for hearing in human and zebrafish,” Human Molecular Genetics 32:1184–1192, advance publication 10 November 2022, issue publication 2023, DOI 10.1093/hmg/ddac257. The retrieved record did not expose a PMID, so no PMID is supplied rather than guessed. A complementary pleiotropic STX4 study is Perl et al., “Stx4 is required to regulate cardiomyocyte Ca2+ handling during vertebrate cardiac development,” published July 2022, DOI 10.1016/j.xhgg.2022.100115. (perl2022stx4isrequired pages 11-13, schrauwen2023syntaxin4is pages 1-2)

Domain Best-supported finding Evidence type/sample Certainty/limitations
Defining human phenotype One consanguineous Pakistani family had eight affected relatives with bilateral severe-to-profound or profound hearing impairment and no consistent vestibular, facial, neurologic, or cardiac abnormality, supporting a predominantly nonsyndromic phenotype. (schrauwen2023syntaxin4is pages 1-2) Human pedigree; eight affected and five unaffected examined; pure-tone audiometry at 250–8000 Hz in affected individuals aged 10–25 years. Strong within-family evidence, but only one DFNB123 family has been published; congenital onset, progression, sex effects, and population-level penetrance remain unestablished.
Gene and inheritance Hearing impairment segregated as an autosomal-recessive trait with homozygous STX4 NM_004604.5:c.232+6T>C; two-point LOD score was 5.9 at θ=0. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 1-2) Exome sequencing, homozygosity mapping, linkage analysis, and Sanger segregation in a large consanguineous pedigree. Compelling locus-level segregation, although independent DFNB123 families and additional alleles are needed for replication.
Variant rarity c.232+6T>C had gnomAD v2 MAF 7.98×10⁻⁶, observed heterozygously in two non-Finnish Europeans, and was absent from gnomAD v3, TOPMed Bravo, GME, and the examined All of Us release. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 1-2) Population-database analysis; ClinVar submission SCV002499562. (schrauwen2023syntaxin4is pages 7-8) Supports PM2 rarity; carrier frequency and disease prevalence cannot be estimated reliably from one exceptionally rare allele.
RNA consequence A minigene assay demonstrated that c.232+6T>C disrupts splicing and causes exon 3 skipping, producing a frameshift predicted to trigger nonsense-mediated decay. (schrauwen2023syntaxin4is pages 2-3) In-vitro functional splicing assay plus computational prediction. Direct evidence for aberrant splicing; nonsense-mediated decay and loss of STX4 protein were predicted rather than demonstrated in patient cochlear tissue.
Cochlear expression/localization Murine Stx4a is broadly expressed in the developing and adult inner ear; STX4A localized to the stereocilia, plasma membrane, and cell body/cytoplasm of inner and outer hair cells, with expression also reported in spiral and vestibular ganglia. (schrauwen2023syntaxin4is pages 2-3) Mouse transcriptomic datasets and P12 cochlear immunofluorescence. Strong anatomical plausibility, but mouse localization does not by itself identify the precise human pathogenic process.
Zebrafish functional evidence Morpholino knockdown of stx4 caused abnormal acoustic startle/ABER responses, absent or markedly impaired FM1-43 uptake in neuromast hair cells, developmental abnormalities, and impaired mechanotransduction. (schrauwen2023syntaxin4is pages 3-6) Zebrafish larvae; ATG- and splice-blocking morpholinos; behavioral, ABER, and FM1-43 assays at 5 dpf. Supports conserved auditory function, but morpholino toxicity, multisystem developmental defects, lack of a stable auditory knockout/rescue model, and species-specific splicing limit mechanistic specificity.
Proposed mechanism STX4 is a target-SNARE involved in membrane fusion and vesicle trafficking; loss is proposed to disturb apical recycling/stereocilia maintenance and/or basal synaptic trafficking, leading to defective hair-cell mechanotransduction and auditory signaling. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 3-6) Integration of protein function, cochlear localization, human splicing, and zebrafish assays. Variant→aberrant splicing and knockdown→mechanotransduction deficit are demonstrated; the intervening vesicle-trafficking and synaptic steps remain inferred.
Phenotypic boundary DFNB123 should be distinguished from broader biallelic STX4 disease: a separate homozygous p.Arg240Trp patient had congenital sensorineural hearing loss, developmental delay, hypotonia, myopathy, and severe dilated cardiomyopathy, while another compound-heterozygous patient had lethal multisystem fetal disease. (perl2022stx4isrequired pages 6-7, perl2022stx4isrequired pages 11-13) Two unrelated human cases plus CRISPR zebrafish cardiac studies. Establishes possible allelic pleiotropy but does not show that cardiac or neurologic disease is part of the c.232+6T>C DFNB123 phenotype; ECGs were normal in two members of the nonsyndromic family.
Treatment and trials No DFNB123-specific drug, gene/RNA/cell therapy, or relevant clinical trial has been reported; the defining study recommends adding STX4 to diagnostic hearing-loss panels. (schrauwen2023syntaxin4is pages 3-6) Literature and trial search; defining family report. Evidence is absent rather than negative. A separate pleiotropic p.Arg240Trp patient received a cochlear implant at age six with improved communication, but this single case is not evidence of genotype-specific efficacy. (perl2022stx4isrequired pages 6-7)

Table: Concise evidence map for the human genetic association, phenotype, functional validation, mechanistic interpretation, phenotypic boundaries, and therapeutic status of STX4-related DFNB123 hearing loss.

1. Disease information

Definition. DFNB123 denotes autosomal-recessive, predominantly nonsyndromic, bilateral severe-to-profound hearing impairment caused by biallelic STX4 dysfunction. The defining family had no consistent vestibular, facial, neurologic, or cardiac phenotype; ECGs were normal in two tested affected relatives. One individual was borderline macrocephalic, but macrocephaly is not established as part of DFNB123. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 3-6)

Names/synonyms: DFNB123; STX4-related autosomal-recessive nonsyndromic hearing loss; STX4-related hearing impairment; syntaxin-4-related hearing loss. “STX4-related disorder” should be reserved for the wider allelic spectrum because other biallelic variants have produced multisystem disease. (perl2022stx4isrequired pages 6-7, perl2022stx4isrequired pages 11-13)

Identifiers. The user-supplied identifier is MONDO:0958277, but it could not be independently verified in the retrieved resources. Open Targets maps STX4 (Ensembl ENSG00000103496) to MONDO’s broader “hearing loss, autosomal recessive” (MONDO:0019588) and “nonsyndromic genetic hearing loss” (MONDO:0019497); its underlying evidence display was sparse and should not replace the primary pedigree report. Disease-specific OMIM, Orphanet, MeSH, ICD-10, and ICD-11 identifiers were not recoverable from the retrieved evidence. General clinical coding will therefore usually use sensorineural or congenital hearing-loss categories rather than a DFNB123-specific code. (OpenTargets Search: autosomal recessive nonsyndromic hearing loss-STX4)

The evidence is aggregated disease-level literature derived from a deeply phenotyped family, not EHR-derived population data. The foundational study examined eight affected and five unaffected relatives. (schrauwen2023syntaxin4is pages 6-7, schrauwen2023syntaxin4is pages 3-6)

2. Etiology

The primary cause is germline, biallelic STX4 dysfunction. In the defining pedigree, homozygosity for c.232+6T>C disrupts normal splicing; environmental causes including infection, ototoxic medication, and trauma were specifically excluded. No susceptibility loci, modifier genes, protective alleles, epigenetic determinants, or reproducible gene–environment interactions are known. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 6-7)

Consanguinity is a reproductive/genetic-context risk factor because it increases the probability that both parents carry the same rare allele. For two heterozygous parents, standard autosomal-recessive counseling implies a 25% affected, 50% carrier, and 25% unaffected/non-carrier probability per pregnancy; these are Mendelian expectations, not empirically measured DFNB123 penetrance estimates.

Noise avoidance and avoidance of ototoxic agents remain prudent for preserving residual hearing, but neither prevents the initiating genetic lesion, and no STX4-specific protective environmental factor has been demonstrated.

3. Phenotypes

The core phenotype is bilateral severe-to-profound or profound hearing impairment, documented by pure-tone audiometry over 250–8000 Hz in affected relatives aged 10–25 years. Suggested HPO terms are Sensorineural hearing impairment (HP:0000407), Bilateral sensorineural hearing impairment (HP:0008619), Severe hearing impairment (HP:0012714), and Profound hearing impairment (HP:0012715). The publication describes congenital hearing impairment at the study level, but the retrieved individual data do not establish exact onset in every relative; “congenital” should therefore be curated with caution. (schrauwen2023syntaxin4is pages 1-2, schrauwen2023syntaxin4is pages 6-7)

No vestibular dysfunction was detected by history, tandem gait, or Romberg testing; facial and neurological examinations were normal. Increased head circumference was noted, but only one person reached borderline macrocephaly (+2 SD), making Macrocephaly (HP:0000256) an uncertain rather than defining association. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 6-7)

Severity was consistently high in the family, but stable versus progressive course, audiometric configuration, speech discrimination, age of first words, tinnitus, and longitudinal frequency-specific threshold change were not reported. Formal EQ-5D, SF-36, PROMIS, or hearing-specific quality-of-life scores are unavailable. Severe early bilateral hearing loss would be expected to affect speech/language acquisition, education, and communication, but these generic consequences were not quantified in DFNB123.

4. Genetic and molecular information

Causal gene: STX4 (syntaxin 4; Ensembl ENSG00000103496). It encodes a plasma-membrane t-SNARE with an N-terminal peptide, Habc regulatory/stabilization region, coiled-coil SNARE-homology domain, and transmembrane region. (OpenTargets Search: autosomal recessive nonsyndromic hearing loss-STX4, perl2022stx4isrequired pages 7-9)

Defining DFNB123 allele: NM_004604.5:c.232+6T>C, alternatively NM_001272096.1:c.226+6T>C. It is a germline splice-region SNV, submitted to ClinVar as SCV002499562. It had CADD 23, gnomAD-v2 MAF 7.98×10⁻⁶, was seen heterozygously in two non-Finnish Europeans, and was absent from gnomAD-v3, TOPMed Bravo, GME, and the examined All of Us release. Homozygosity mapping, segregation, and linkage gave LOD 5.9 at θ=0. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 1-2, schrauwen2023syntaxin4is pages 7-8)

A minigene assay demonstrated exon-3 skipping and a resulting frameshift. Nonsense-mediated decay and complete protein loss are biologically plausible but were predicted rather than measured in patient cochlear tissue. The evidence supports a loss-of-function mechanism; no gain-of-function or dominant-negative mechanism is demonstrated. (schrauwen2023syntaxin4is pages 2-3)

Other biallelic STX4 alleles—not defining nonsyndromic DFNB123: homozygous c.718C>T, p.Arg240Trp produced congenital sensorineural hearing loss plus developmental delay, hypotonia, myopathy, and severe dilated cardiomyopathy; compound-heterozygous c.89_90delGC, p.Gly30Aspfs*28 and c.232+4A>C occurred in a fetus with lethal multisystem disease. The p.Arg240Trp-equivalent zebrafish allele behaved as hypomorphic. These cases show allelic pleiotropy and argue against assuming that every biallelic STX4 genotype is nonsyndromic. (perl2022stx4isrequired pages 6-7, perl2022stx4isrequired pages 11-13)

No validated modifier gene, disease-specific methylation signature, chromosomal rearrangement, somatic event, or repeat expansion has been reported.

5. Environmental information

DFNB123 is genetic, not infectious, toxic, nutritional, occupational, radiation-induced, or lifestyle-mediated. Infection, ototoxic drugs, and trauma were excluded in the defining family. No smoking, diet, alcohol, exercise, pollution, infectious-agent, or chemical interaction with STX4 has been demonstrated. (schrauwen2023syntaxin4is pages 6-7)

6. Mechanism/pathophysiology

Ordered causal chain

  1. Homozygous STX4 c.232+6T>C leads to exon-3 skipping in a minigene assay. (schrauwen2023syntaxin4is pages 2-3)
  2. Exon skipping results in a frameshift predicted to trigger nonsense-mediated decay, leading to reduced functional syntaxin-4; protein depletion in patient cochlea remains inferred. (schrauwen2023syntaxin4is pages 2-3)
  3. Loss of syntaxin-4 is inferred to impair target-SNARE-mediated membrane fusion and vesicle recycling in cochlear hair cells, where STX4A localizes to stereocilia, plasma membrane, and cytoplasm. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 1-2)
  4. Impaired apical trafficking is inferred to disrupt stereocilia maintenance and/or organization of the mechanotransduction apparatus. This branch is supported by absent FM1-43 uptake after zebrafish stx4 knockdown but has not been resolved molecularly in human cells. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 3-6)
  5. Possible basal branch: defective vesicle trafficking is inferred to impair synaptic exocytosis/recycling and afferent signaling; this has not been directly demonstrated for STX4 at mammalian inner-hair-cell ribbon synapses. (schrauwen2023syntaxin4is pages 3-6, schrauwen2023syntaxin4is pages 1-2)
  6. Hair-cell mechanotransduction/auditory signaling failure leads to abnormal zebrafish ABER/startle responses and, in homozygous humans, bilateral severe-to-profound hearing impairment. (schrauwen2023syntaxin4is pages 1-2, schrauwen2023syntaxin4is pages 3-6)

STX4 participates broadly in vesicle docking/fusion and recycling rather than a canonical Wnt, MAPK, mTOR, or PI3K-AKT disease cascade. Relevant suggested GO annotations include SNARE complex assembly (GO:0035493), vesicle fusion (GO:0006906), exocytosis (GO:0006887), endocytic recycling (GO:0032456), sensory perception of sound (GO:0007605), and mechanosensory behavior (GO:0007638). Suggested cellular components include plasma membrane (GO:0005886), SNARE complex (GO:0031201), and stereocilium (GO:0032420).

Mouse data place STX4A in inner and outer hair cells and also report expression in spiral and vestibular ganglia. Suggested Cell Ontology terms are inner hair cell (CL:0000589), outer hair cell (CL:0000601), and spiral-ganglion neuron where an appropriate current CL term is available. (schrauwen2023syntaxin4is pages 2-3)

No DFNB123-specific metabolomic, lipidomic, proteomic, epigenomic, patient transcriptomic, spatial-transcriptomic, multi-omic, organoid, iPSC, or CRISPR-screen signature has been reported. Available advanced data are mainly reanalysis of mouse developmental, microarray, and single-cell expression resources plus cochlear immunofluorescence. (schrauwen2023syntaxin4is pages 7-8, schrauwen2023syntaxin4is pages 2-3)

Complementary cardiac work demonstrates that CRISPR stx4 loss reduces Vamp2-positive vesicle docking at the cardiomyocyte sarcolemma and alters L-type Ca²⁺-channel-dependent calcium handling. This validates a general STX4 trafficking role but should not be substituted for a directly demonstrated cochlear mechanism. (perl2022stx4isrequired pages 7-9, perl2022stx4isrequired pages 13-14)

7. Anatomical structures affected

The principal organ is the inner ear, particularly the cochlea and its sensory epithelium/organ of Corti. Suggested UBERON terms are inner ear (UBERON:0001846), cochlea (UBERON:0001844), and organ of Corti (UBERON:0002227). At cellular level, inner and outer hair cells are implicated; at subcellular level, stereocilia, plasma membrane, and cytoplasm are involved. Expression in spiral and vestibular ganglia provides anatomical plausibility, although no clinical vestibular deficit was observed. Disease is bilateral. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 1-2)

Cardiac, skeletal-muscle, neurologic, renal, and gastrointestinal involvement belongs to the broader biallelic STX4 spectrum, not the established c.232+6T>C DFNB123 phenotype. (perl2022stx4isrequired pages 6-7, perl2022stx4isrequired pages 11-13)

8. Temporal development

The disorder is characterized as congenital/early hearing impairment, and STX4 is expressed in both developing and adult mouse inner ear. Nevertheless, individual onset ages were not documented sufficiently to establish universal congenital onset. Audiometry at ages 10–25 years confirmed persistent severe disease. Progression rate, stages, fluctuation, remission, and untreated longitudinal course are unknown. (schrauwen2023syntaxin4is pages 1-2)

The clinically important intervention window is infancy and early childhood, when auditory access supports speech and language development; this is a general congenital-hearing-loss principle rather than a measured STX4-specific critical period. The defining article explicitly emphasizes prompt recognition and intervention. (schrauwen2023syntaxin4is pages 1-2)

9. Inheritance and population

Inheritance is autosomal recessive. All eight affected relatives in the reported consanguineous family were homozygous, while carrier parents were unaffected, consistent with high penetrance within that pedigree. Linkage modeling assumed complete penetrance; this assumption is not equivalent to a population estimate. Anticipation and germline mosaicism have not been reported. (schrauwen2023syntaxin4is pages 6-7, schrauwen2023syntaxin4is pages 1-2)

Only one DFNB123 family was found among 473 hearing-loss families in the investigators’ dataset, and no independent second family was identified. This is a discovery-cohort proportion, not prevalence. No incidence per 100,000, carrier frequency, sex ratio, or geographic prevalence is available. The only established concentration is the reported consanguineous family from Khyber Pakhtunkhwa, Pakistan; the allele’s two gnomAD carriers were non-Finnish European. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 1-2, schrauwen2023syntaxin4is pages 3-6)

10. Diagnostics

The clinical evaluation should establish bilateral sensorineural hearing loss using newborn hearing screening, diagnostic ABR/ABER where age-appropriate, otoacoustic emissions, tympanometry, and pure-tone/speech audiometry. The defining study used 250–8000-Hz pure-tone audiometry, vestibular history, tandem gait, Romberg testing, physical/neurological examination, and selected ECGs. (schrauwen2023syntaxin4is pages 6-7)

Preferred molecular approach: a comprehensive hearing-loss panel that includes STX4, with deletion/duplication analysis; exome or genome sequencing is appropriate after negative panel testing or where a multisystem phenotype is present. The authors explicitly recommended adding STX4 to diagnostic panels. Candidate variants require parental segregation and phenotype review. RNA analysis or a minigene assay can clarify noncanonical splice variants. (schrauwen2023syntaxin4is pages 3-6, schrauwen2023syntaxin4is pages 6-7)

The discovery workflow excluded coding GJB2/common hearing-loss variants, used WES, homozygosity mapping, CNV analysis, Sanger segregation, linkage, population-frequency filtering, and functional splice testing. CMA, karyotyping, FISH, mitochondrial testing, and repeat-expansion testing are not targeted assays for this sequence-level disorder but may be selected when the broader phenotype suggests another diagnosis. (schrauwen2023syntaxin4is pages 6-7)

Differential diagnosis includes the many other autosomal-recessive nonsyndromic hearing-loss genes—especially GJB2 and genes causing severe congenital disease—and acquired infection, ototoxicity, or trauma. Cardiac examination and consideration of ECG/echocardiography are reasonable when a patient has p.Arg240Trp, truncating alleles, weakness, hypotonia, developmental delay, arrhythmia, or cardiomyopathy because broader STX4 disease can be pleiotropic. This surveillance proposal is precautionary and not a formal guideline. (perl2022stx4isrequired pages 6-7, perl2022stx4isrequired pages 11-13)

Cascade testing can identify carriers and affected relatives. Prenatal diagnosis and PGT-M are technically feasible once familial pathogenic variants are known, subject to local regulation and nondirective counseling.

11. Outcome and prognosis

No DFNB123-specific mortality, survival, or life-expectancy decrement is documented. The nonsyndromic family had no reported life-threatening manifestation. Hearing impairment appears chronic and severe, with no spontaneous remission reported, but longitudinal stability versus progression is unknown. Formal disability and quality-of-life outcomes are unavailable. (schrauwen2023syntaxin4is pages 3-6, schrauwen2023syntaxin4is pages 1-2)

Broader STX4 disease can be severe: the p.Arg240Trp patient required heart transplantation, and the compound-heterozygous fetus died at five days from multiorgan failure. These outcomes must not be assigned to DFNB123 c.232+6T>C without evidence. (perl2022stx4isrequired pages 6-7)

12. Treatment

No STX4-directed drug, gene replacement, gene editing, ASO, siRNA, mRNA, cell therapy, or disease-specific pharmacogenomic strategy is available. No relevant STX4/DFNB123 interventional trial was identified in the tool search. (schrauwen2023syntaxin4is pages 3-6, schrauwen2023syntaxin4is pages 2-3)

Current care should follow severity- and age-appropriate hearing-loss practice: hearing aids when useful, cochlear-implant evaluation for severe-to-profound loss with inadequate aided speech access, speech/language or auditory-verbal therapy, educational accommodations, and Deaf/community communication options according to patient and family preference. Suggested NCIt terms include Hearing Aid Device (NCIt concept where current), Cochlear Implantation, Speech Therapy, and Audiologic Rehabilitation; exact current NCIt identifiers should be ontology-validated before database loading.

The separate p.Arg240Trp patient’s hearing aids were replaced by a cochlear implant at age six, with improved communication. This is a single pleiotropic case and neither a response rate nor proof of STX4-specific implant efficacy. (perl2022stx4isrequired pages 6-7)

The LTCC agonist Bay K-8644 rescued zebrafish cardiac bradycardia, not hearing. It is mechanistic model evidence and not a proposed human DFNB123 treatment. (perl2022stx4isrequired pages 11-13, perl2022stx4isrequired pages 13-14)

13. Prevention

There is no primary lifestyle or vaccine prevention for a germline recessive disorder. Primary genetic prevention options are informed reproductive choice after carrier testing, including natural conception with prenatal diagnosis, PGT-M, donor gametes, or adoption; counseling must remain nondirective.

Secondary prevention consists of universal newborn hearing screening, rapid diagnostic audiology, early molecular testing, cascade testing, and prompt auditory/communication intervention. Tertiary prevention includes amplification or implantation where indicated, communication rehabilitation, educational support, and avoidance of additional noise or ototoxic injury. No medication prophylaxis or immunization is disease-specific. The family data support recessive carrier and relative testing but do not constitute a formal prevention trial. (schrauwen2023syntaxin4is pages 1-2, schrauwen2023syntaxin4is pages 2-3)

14. Other species and natural disease

Experimental evidence exists in Danio rerio (zebrafish; NCBI Taxon 7955) and expression/localization evidence in Mus musculus (mouse; Taxon 10090). No naturally occurring veterinary STX4 deafness syndrome, breed association, OMIA entry, zoonotic transmission, or cross-species infectious risk was identified. Human and zebrafish findings support evolutionary conservation of STX4-dependent auditory function. (schrauwen2023syntaxin4is pages 1-2, schrauwen2023syntaxin4is pages 2-3)

15. Model organisms

Zebrafish auditory model: ATG- and splice-blocking morpholinos at approximately 9 ng were evaluated at five days post-fertilization. Knockdown caused reduced 1-kHz auditory/startle responses, with reported P values of 0.0001 and 0.0017, absent/impaired FM1-43 uptake in neuromast hair cells, edema, increased head size, and broad developmental abnormalities. It recapitulates impaired mechanotransduction and auditory behavior but not a clean isolated human DFNB123 phenotype. Limitations include morpholino toxicity/off-target effects, developmental pleiotropy, absence of a stable knock-in/rescue auditory model, and species-specific splicing—the zebrafish splice morpholino caused intron retention, whereas human c.232+6T>C caused exon skipping. (schrauwen2023syntaxin4is pages 3-6, schrauwen2023syntaxin4is pages 7-8)

Mouse: developmental datasets and P12 immunofluorescence establish cochlear expression and hair-cell localization, but no hearing phenotype from a cochlea-specific Stx4 knockout was reported. Global Stx4 knockout is embryonic lethal, limiting adult auditory study. (schrauwen2023syntaxin4is pages 2-3, perl2022stx4isrequired pages 6-7)

CRISPR zebrafish cardiac model: a 38-bp exon-3 splice-donor deletion generated out-of-frame transcripts and broad developmental/cardiac disease. It is useful for SNARE-dependent vesicle docking, Ca²⁺ handling, and allelic hypomorphism, but is not a specific DFNB123 model. (perl2022stx4isrequired pages 7-9, perl2022stx4isrequired pages 11-13)

No reported rat, Drosophila, C. elegans, yeast, patient-iPSC, cochlear-organoid, or humanized knock-in DFNB123 model was identified.

Evidence appraisal and 2023–2024 status

The 2023 Schrauwen study remains the pivotal and most recent retrieved DFNB123-specific primary report. Its strengths are eight affected relatives, strong segregation/linkage, extreme allele rarity, functional splice validation, cross-species localization, and auditory assays. Its central limitations are a single pedigree, one DFNB123 allele, morpholino rather than stable auditory modeling, no patient-derived cochlear tissue, and sparse longitudinal and treatment data. The authors’ own expert conclusion was that STX4 should be added to diagnostic hearing-loss panels and that additional families are required to define the phenotype. (schrauwen2023syntaxin4is pages 2-3, schrauwen2023syntaxin4is pages 3-6)

A suitable exact abstract quotation is: “This identified a homozygous splice region variant in STX4 (c.232 + 6 T > C), which causes exon skipping and a frameshift, that segregated with hearing impairment (two-point LOD score = 5.9).” A second is: “Our findings indicate that STX4 dysfunction leads to hearing impairment in humans and zebrafish and supports the evolutionary conserved role of STX4 in inner ear development and hair cell functioning.” (schrauwen2023syntaxin4is pages 1-2)

No retrieved 2024 primary study independently replicated DFNB123, supplied epidemiologic estimates, or advanced an STX4-specific therapy. Accordingly, this knowledge-base entry should be labeled limited human evidence/one replicated-within-family locus report, with the nonsyndromic DFNB123 phenotype kept distinct from severe multisystem biallelic STX4 disease.

References

  1. (schrauwen2023syntaxin4is pages 2-3): Isabelle Schrauwen, Amama Ghaffar, Thashi Bharadwaj, Khadim Shah, Sakina Rehman, Anushree Acharya, Khurram Liaqat, Nicole S Lin, Jenna L Everard, Anwar Khan, Zubair M Ahmed, Wasim Ahmad, Saima Riazuddin, and Suzanne M Leal. Syntaxin 4 is essential for hearing in human and zebrafish. Human molecular genetics, 32:1184-1192, Nov 2023. URL: https://doi.org/10.1093/hmg/ddac257, doi:10.1093/hmg/ddac257. This article has 3 citations and is from a domain leading peer-reviewed journal.

  2. (schrauwen2023syntaxin4is pages 1-2): Isabelle Schrauwen, Amama Ghaffar, Thashi Bharadwaj, Khadim Shah, Sakina Rehman, Anushree Acharya, Khurram Liaqat, Nicole S Lin, Jenna L Everard, Anwar Khan, Zubair M Ahmed, Wasim Ahmad, Saima Riazuddin, and Suzanne M Leal. Syntaxin 4 is essential for hearing in human and zebrafish. Human molecular genetics, 32:1184-1192, Nov 2023. URL: https://doi.org/10.1093/hmg/ddac257, doi:10.1093/hmg/ddac257. This article has 3 citations and is from a domain leading peer-reviewed journal.

  3. (schrauwen2023syntaxin4is pages 3-6): Isabelle Schrauwen, Amama Ghaffar, Thashi Bharadwaj, Khadim Shah, Sakina Rehman, Anushree Acharya, Khurram Liaqat, Nicole S Lin, Jenna L Everard, Anwar Khan, Zubair M Ahmed, Wasim Ahmad, Saima Riazuddin, and Suzanne M Leal. Syntaxin 4 is essential for hearing in human and zebrafish. Human molecular genetics, 32:1184-1192, Nov 2023. URL: https://doi.org/10.1093/hmg/ddac257, doi:10.1093/hmg/ddac257. This article has 3 citations and is from a domain leading peer-reviewed journal.

  4. (perl2022stx4isrequired pages 11-13): Eliyahu Perl, Padmapriyadarshini Ravisankar, Manu E. Beerens, Lejla Mulahasanovic, Kelly Smallwood, Marion Bermúdez Sasso, Carina Wenzel, Thomas D. Ryan, Matej Komár, Kevin E. Bove, Calum A. MacRae, K. Nicole Weaver, Carlos E. Prada, and Joshua S. Waxman. Stx4 is required to regulate cardiomyocyte ca2+ handling during vertebrate cardiac development. Jul 2022. URL: https://doi.org/10.1016/j.xhgg.2022.100115, doi:10.1016/j.xhgg.2022.100115. This article has 9 citations and is from a peer-reviewed journal.

  5. (schrauwen2023syntaxin4is pages 7-8): Isabelle Schrauwen, Amama Ghaffar, Thashi Bharadwaj, Khadim Shah, Sakina Rehman, Anushree Acharya, Khurram Liaqat, Nicole S Lin, Jenna L Everard, Anwar Khan, Zubair M Ahmed, Wasim Ahmad, Saima Riazuddin, and Suzanne M Leal. Syntaxin 4 is essential for hearing in human and zebrafish. Human molecular genetics, 32:1184-1192, Nov 2023. URL: https://doi.org/10.1093/hmg/ddac257, doi:10.1093/hmg/ddac257. This article has 3 citations and is from a domain leading peer-reviewed journal.

  6. (perl2022stx4isrequired pages 6-7): Eliyahu Perl, Padmapriyadarshini Ravisankar, Manu E. Beerens, Lejla Mulahasanovic, Kelly Smallwood, Marion Bermúdez Sasso, Carina Wenzel, Thomas D. Ryan, Matej Komár, Kevin E. Bove, Calum A. MacRae, K. Nicole Weaver, Carlos E. Prada, and Joshua S. Waxman. Stx4 is required to regulate cardiomyocyte ca2+ handling during vertebrate cardiac development. Jul 2022. URL: https://doi.org/10.1016/j.xhgg.2022.100115, doi:10.1016/j.xhgg.2022.100115. This article has 9 citations and is from a peer-reviewed journal.

  7. (OpenTargets Search: autosomal recessive nonsyndromic hearing loss-STX4): Open Targets Query (autosomal recessive nonsyndromic hearing loss-STX4, 2 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

  8. (schrauwen2023syntaxin4is pages 6-7): Isabelle Schrauwen, Amama Ghaffar, Thashi Bharadwaj, Khadim Shah, Sakina Rehman, Anushree Acharya, Khurram Liaqat, Nicole S Lin, Jenna L Everard, Anwar Khan, Zubair M Ahmed, Wasim Ahmad, Saima Riazuddin, and Suzanne M Leal. Syntaxin 4 is essential for hearing in human and zebrafish. Human molecular genetics, 32:1184-1192, Nov 2023. URL: https://doi.org/10.1093/hmg/ddac257, doi:10.1093/hmg/ddac257. This article has 3 citations and is from a domain leading peer-reviewed journal.

  9. (perl2022stx4isrequired pages 7-9): Eliyahu Perl, Padmapriyadarshini Ravisankar, Manu E. Beerens, Lejla Mulahasanovic, Kelly Smallwood, Marion Bermúdez Sasso, Carina Wenzel, Thomas D. Ryan, Matej Komár, Kevin E. Bove, Calum A. MacRae, K. Nicole Weaver, Carlos E. Prada, and Joshua S. Waxman. Stx4 is required to regulate cardiomyocyte ca2+ handling during vertebrate cardiac development. Jul 2022. URL: https://doi.org/10.1016/j.xhgg.2022.100115, doi:10.1016/j.xhgg.2022.100115. This article has 9 citations and is from a peer-reviewed journal.

  10. (perl2022stx4isrequired pages 13-14): Eliyahu Perl, Padmapriyadarshini Ravisankar, Manu E. Beerens, Lejla Mulahasanovic, Kelly Smallwood, Marion Bermúdez Sasso, Carina Wenzel, Thomas D. Ryan, Matej Komár, Kevin E. Bove, Calum A. MacRae, K. Nicole Weaver, Carlos E. Prada, and Joshua S. Waxman. Stx4 is required to regulate cardiomyocyte ca2+ handling during vertebrate cardiac development. Jul 2022. URL: https://doi.org/10.1016/j.xhgg.2022.100115, doi:10.1016/j.xhgg.2022.100115. This article has 9 citations and is from a peer-reviewed journal.

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