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Classifications

Harrison's Part

🔗

Mappings

MONDO

MONDO:0007473 Duane retraction syndrome DisMech

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Inheritance

1

Autosomal dominant inheritance HP:0000006

Heterozygous MAFB variants are sufficient to cause disease, and affected parent-to-child transmission has been documented. Both inherited and de novo variants occur.

Autosomal dominant inheritance

Show evidence (3 references)

PMID:20301369 SUPPORT Human Clinical

"Duane syndrome resulting from a CHN1, MAFB, or SALL4 pathogenic variant is inherited in an autosomal dominant manner."

GeneReviews states that MAFB-related Duane syndrome is autosomal dominant.

PMID:27181683 SUPPORT Human Clinical

"Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness."

The founding report establishes that single heterozygous MAFB alleles cause the disease, consistent with dominant inheritance.

PMID:20301369 SUPPORT Human Clinical

"Each child of an individual with Duane syndrome resulting from an identified pathogenic variant has a 50% chance of inheriting the variant."

Gives the recurrence risk that follows from dominant inheritance, which is the operative fact for counselling a MAFB carrier.

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Discussions and Knowledge Gaps

2

Why does one copy of MAFB p.Leu239Pro cause focal segmental glomerulosclerosis and Duane retraction syndrome in a person, while the dose-matched heterozygous knock-in mouse stays healthy?

HUMAN MODEL MISMATCH OPEN mafb_het_mouse_dose_mismatch

Attached to

pathophysiology#Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure pathophysiology#MAFB Transcriptional Output Falls Below Its Developmental Threshold

The threshold model this entry is built on predicts that phenotype tracks the size of the shortfall in MAFB output. The mouse puts a number on where that threshold sits, and it is not in the same place in the two species: in the mouse, one mutant copy is tolerated and only the homozygote is affected, whereas in people one copy produces glomerulosclerosis and a cranial nerve that never formed. This is not a missing experiment; the heterozygote was examined and was normal. It matters for interpretation, because a negative result in a heterozygous mouse would otherwise look like evidence against a human MAFB allele being pathogenic, and it matters for the model, because it says the threshold is a property of the species and not of the protein. Candidate explanations include a difference in how much MafB the developing mouse glomerulus and hindbrain actually need, the far longer period over which a human glomerulus must be maintained, and modifier background. None has been tested.

Proposed experiments

Quantify MAFB target-gene output at matched heterozygous dose in both species

mafb_het_dose_output_comparison

Measure MARE-driven target-gene transcription in podocytes and in rhombomere-5-derived motor neurons from heterozygous mouse and from human induced pluripotent stem cell lines carrying the same substitution, to establish whether the two species differ in residual output or in sensitivity to the same residual output.

Show evidence (2 references)

PMID:37895232 SUPPORT Model Organism

"In contrast, Mafb heterozygous mutant mice could stay healthy without any abnormal podocyte formation or kidney function."

The negative result in the dose-matched mouse that creates the mismatch.

PMID:29779709 SUPPORT Human Clinical

"Genetic analyses revealed that affected individuals harbor a rare heterozygous substitution (p.Leu239Pro) in MAFB, a leucine zipper transcription factor."

The human side of the mismatch: heterozygous carriers of the same substitution are affected.

Should proteinuric kidney disease be treated as part of Duane retraction syndrome 3, or as a separate MAFB-related renal disease that sometimes co-occurs with it?

OPEN QUESTION OPEN mafb_renal_arm_scope

Attached to

pathophysiology#Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure

The MONDO and OMIM labels for this entity name deafness and not kidney disease, yet every affected member of the two families that defined the p.Leu239Pro allele had focal segmental glomerulosclerosis, and a more recently reported family includes a carrier with an isolated renal phenotype and no ocular involvement at all. This entry curates the renal arm on the strength of a 2026 report stating that DRS3 may co-occur with proteinuric kidney disease, but the boundary is genuinely unsettled: the same bZIP alleles are also reported under headings such as MAFB-associated glomerulopathy. The practical question is whether a carrier with kidney disease alone should be recorded as having this entity. Until a nosological decision is made, this entry keeps the renal features and marks them as variable rather than defining.

Show evidence (2 references)

PMID:41898877 SUPPORT Human Clinical

"Duane retraction syndrome 3 (DRS3; OMIM #617041), a congenital ocular cranial dysinnervation disorder that may co-occur with proteinuric kidney disease."

The statement this entry relies on to bring the renal arm inside the boundary of DRS3.

PMID:41898877 SUPPORT Human Clinical

"This patient denied a history of hearing impairment, ocular abnormalities, or neurodevelopmental disorders."

A carrier of the same variant with kidney disease and no ocular, otic, or neurodevelopmental features, which is what makes the boundary question live.

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Pathophysiology

7

MAFB Transcriptional Output Falls Below Its Developmental Threshold

MAFB is a single-exon large-MAF basic leucine zipper transcription factor that homodimerizes and binds MAF recognition elements (MAREs) to drive transcription of nearby target genes. The DURS3 alleles reduce that output by two routes. Heterozygous truncating and other loss-of-function alleles halve the dose; missense alleles in or beside the C-terminal DNA-binding region, of which p.Leu239Pro is the best characterized, leave a protein that cannot engage the MARE and can additionally poison the wild-type partner in the dimer, giving a dominant-negative allele. Engle and colleagues framed the resulting allelic series as a threshold model, in which the depth of the shortfall determines how much of the MAFB-dependent developmental program is lost and therefore how far the phenotype extends beyond the eye.

Genetic context MAFB hgnc:6408 variant_origin: GERMLINE zygosity: HETEROZYGOUS functional_impact_category: LOSS_OF_FUNCTION

Heterozygous germline MAFB alleles. Three loss-of-function alleles and one dominant-negative missense allele were reported in the founding cohort; subsequently reported DURS3-spectrum missense alleles cluster in or beside the bZIP DNA-binding region.

sequence-specific MARE binding by the MAFB bZIP domain GO:0003700 ↓ DECREASED

Animal models

Mafb p.Leu239Pro homozygous knock-in mouse Mouse recapitulates Reproduces the molecular lesion itself, since it is the identical residue change found in affected people, and confirms that the substitution abolishes rather than merely alters MafB function.

Downstream

Failure of Rhombomere 5 Patterning and Abducens Motor Neuron Specification Reduced MAFB-driven transcription removes the segmental identity signal that the hindbrain uses to build the abducens motor neuron pool.

Impaired MAFB-Dependent Inner Ear Morphogenesis The same shortfall in MAFB output disrupts otic development, the parallel arm that produces the deafness named in the disease label.

Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure MAFB is separately required in the developing glomerulus, so DNA-binding domain alleles can additionally compromise the podocyte program.

Show evidence (6 references)

PMID:27181683 SUPPORT Human Clinical

"Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness."

Establishes the two allelic classes, reduced dose and dominant-negative, that lower MAFB output in this disease.

PMID:27181683 SUPPORT Human Clinical

"Using genotype-phenotype correlations in humans and Mafb-knockout mice, we propose a threshold model for variable loss of MAFB function."

States the threshold model that this node encodes, in which the size of the shortfall in MAFB function sets the extent of the phenotype. The quoted sentence spans two evidence types, human genotype-phenotype correlation and Mafb-knockout mice. It is graded HUMAN_CLINICAL because the claim being supported is an allelic-series inference across affected people, which the mouse work extends rather than establishes; the mouse arm of the same paper is graded MODEL_ORGANISM where it is quoted separately on the abducens and reinnervation nodes.

PMID:37895232 SUPPORT Other

"These four transcription factors are thought to be involved in the formation of homodimers and binding to DNA sequences called Maf recognition elements (MAREs) to stimulate the transcriptional activity of nearby target genes."

Describes the normal molecular function that the DURS3 alleles degrade: MARE binding and target-gene transactivation by a MAF homodimer.

+ 3 more references

Failure of Rhombomere 5 Patterning and Abducens Motor Neuron Specification

The abducens motor neurons are born in hindbrain rhombomere 5, and the mouse MAFB ortholog kreisler is required for that segment to form at all. When MAFB function drops, rhombomere 5 identity is not established and the abducens motor neuron pool is not specified. Mafb-null mice lack the sixth nerve motor nuclei outright, and zebrafish lacking the mafba ortholog show absent or hypoplastic abducens nuclei, so the requirement is conserved across vertebrates.

abducens motor neuron CL:0000100

rhombomere 5 development GO:0021571 ↓ DECREASED abducens motor neuron fate specification GO:0048665 ↓ DECREASED

Animal models

Mafb-null mouse Mouse recapitulates Absence of the sixth nerve motor nuclei, the cellular step this node asserts.

mafba-null zebrafish Zebrafish recapitulates Absent or hypoplastic abducens motor nucleus on loss of the MAFB ortholog.

Downstream

Abducens Nerve Hypoplasia and Failure to Innervate the Lateral Rectus Without a specified abducens motor neuron pool, the sixth nerve is hypoplastic or absent and never reaches its target muscle.

Show evidence (3 references)

PMID:10395784 SUPPORT Model Organism

"Using Hox/lacZ transgenic mice as reporter lines and by analyzing Eph/ephrin expression, we have found that while r5 fails to form in these mice, r6 is present. This shows that kreisler has an early role in the formation of r5."

Establishes that the mouse MAFB ortholog is required to form rhombomere 5, the hindbrain segment from which the abducens motor neurons arise.

PMID:40162949 SUPPORT Model Organism

"Monoallelic MAFB LOF causes DRS in humans and absence of CN6 motor nuclei in mice, with secondary aberrant innervation by CN3 of the lateral rectus muscle, which is normally innervated by CN6."

States that reduced MAFB function abolishes the abducens motor nuclei in mice, the cellular step this node models.

PMID:37895232 SUPPORT Other

"Therefore, mutations of MAFB impair the generation and/or inhibit the sustenance of abducens neurons, the inner ear, and podocytes in the kidneys"

A review of the MAF family summarizing that MAFB variants compromise the generation or maintenance of abducens neurons.

Abducens Nerve Hypoplasia and Failure to Innervate the Lateral Rectus

The founding anatomical lesion is a hypoplastic or absent abducens nerve that fails to fully innervate the lateral rectus muscle. This is the dysinnervation event that defines the disease, and it is documented in affected people as well as in mice. The lateral rectus itself is a normal skeletal muscle at this point; what is missing is its motor supply.

abducens nerve development GO:0021560 ↓ DECREASED

Downstream

Aberrant Oculomotor Reinnervation of the Lateral Rectus The denervated lateral rectus is captured by a misrouted branch of the oculomotor nerve growing to nearby extraocular muscle targets.

Show evidence (3 references)

PMID:29779709 SUPPORT Human Clinical

"Hypoplasia of the abducens nerves and hearing impairment occurred in severely affected individuals."

Documents abducens nerve hypoplasia in MAFB variant carriers, and does so in the individuals at the severe end of the threshold, who also had hearing impairment.

PMID:27181683 SUPPORT Model Organism

"Thus, we present evidence that the primary cause of DRS is failure of the abducens nerve to fully innervate the lateral rectus muscle in early development."

Names failed abducens innervation of the lateral rectus as the primary developmental cause, which is why this node and not an extraocular muscle defect is the root of the ocular arm.

PMID:41870107 SUPPORT Human Clinical

"Duane retraction syndrome, the most common CCDD, results from the absence of the abducens nerve and innervation of the lateral rectus by oculomotor nerve axons; causative genes include CHN1, MAFB, HOXA1, SALL4, and EBF3, although most cases do not have a genetic diagnosis."

A current review placing MAFB among the causative genes and stating the absent-abducens-nerve mechanism this node encodes.

Aberrant Oculomotor Reinnervation of the Lateral Rectus

With no abducens input, the lateral rectus is secondarily innervated by aberrant branches of the oculomotor nerve that form at developmental decision regions close to the target extraocular muscles. This is a secondary consequence of the primary abducens failure rather than an independent guidance defect: selectively disrupting abducens development is by itself sufficient to produce the miswiring. The lateral rectus is thereafter yoked to the medial rectus rather than opposing it.

aberrant oculomotor motor neuron CL:0000100 lateral rectus muscle cell CL:0000188

ocular motor axon guidance GO:0008045 ⚠ ABNORMAL

Downstream

Horizontal Rectus Co-contraction and Globe Retraction Shared oculomotor drive makes the lateral and medial recti contract together on attempted adduction.

Show evidence (2 references)

PMID:27181683 SUPPORT Model Organism

"Moreover, we demonstrate that selectively disrupting abducens nerve development is sufficient to cause secondary innervation of the lateral rectus muscle by aberrant oculomotor nerve branches, which form at developmental decision regions close to target extraocular muscles."

Shows experimentally that the aberrant oculomotor reinnervation is downstream of, and caused by, the abducens failure.

PMID:27181683 SUPPORT Human Clinical

"Postmortem studies of DRS have reported abducens nerve hypoplasia and aberrant innervation of the lateral rectus muscle by the oculomotor nerve."

Human postmortem pathology confirming that the lateral rectus receives oculomotor rather than abducens innervation.

Horizontal Rectus Co-contraction and Globe Retraction

Because the lateral rectus now fires on the oculomotor command that also drives the medial rectus, attempted adduction contracts both horizontal recti at once. The opposed forces pull the globe backwards into the orbit, narrowing the palpebral fissure, while abduction remains deficient because the muscle no longer receives an abduction command. This synkinetic miswiring, not weakness or fibrosis of the muscle, is what a clinician sees at the bedside.

horizontal rectus muscle cell CL:0000188

Show evidence (2 references)

PMID:40162949 SUPPORT Human Clinical

"In DRS, CN6 maldevelopment causes limited abduction and variably limited adduction, and the globe retracts on attempted adduction because of synkinetic miswiring by CN3."

Attributes the globe retraction directly to synkinetic oculomotor miswiring, the step this node models.

PMID:20301369 SUPPORT Human Clinical

"globe retraction occurs as a result of abnormal innervation of the lateral rectus muscle by the oculomotor nerve (cranial nerve III)"

GeneReviews states the same causal link between the aberrant innervation and the retraction.

Impaired MAFB-Dependent Inner Ear Morphogenesis

MAFB is independently required for otic development, which is how the mouse gene was first found: the radiation-induced kreisler mutant was recognized by circling behavior caused by an inner-ear defect. In people, the dominant-negative allele that produces the deepest shortfall in MAFB function is the one reported with deafness, and imaging in a bZIP-variant carrier showed cochlear aplasia with a bilateral common cavity. This is a parallel arm of the same molecular lesion, not a consequence of the ocular defect.

inner ear morphogenesis GO:0042472 ↓ DECREASED

Show evidence (3 references)

PMID:37895232 SUPPORT Model Organism

"Further study indicated that MafB plays an important role in segment formation in the hindbrain; in addition, the absence of MafB induces abnormal formation of the inner ear"

States the MAFB requirement for normal inner-ear formation that this node models, alongside its hindbrain segmentation role.

PMID:27181683 SUPPORT Human Clinical

"Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness."

Ties the deafness specifically to the dominant-negative allele, which is the threshold-model prediction for this parallel arm.

PMID:41898877 SUPPORT Human Clinical

"Brain magnetic resonance imaging (MRI) at one year revealed cochlear aplasia with a bilateral common cavity configuration, without additional intracranial abnormalities."

Structural imaging in a MAFB bZIP-variant carrier showing a gross cochlear malformation, the anatomical form this arm can take.

Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure

MAFB is also required in the developing glomerulus for podocyte differentiation and foot-process formation. Carriers of bZIP DNA-binding domain alleles have shown reduced podocyte MAFB by immunohistochemistry, and neonatal mice carrying the same substitution have poorly differentiated podocytes. The clinical consequence is focal segmental glomerulosclerosis and proteinuric kidney disease, which the MONDO and OMIM labels for this entity do not name but which is reported in DURS3-spectrum families. This arm is variably expressed and is not required for the diagnosis.

glomerular podocyte CL:0000653

podocyte differentiation GO:0072112 ↓ DECREASED

Animal models

Mafb p.Leu239Pro homozygous knock-in mouse Mouse recapitulates Newborn homozygotes show defective podocyte differentiation with impaired foot processes, the cellular lesion behind the renal arm.

Mafb p.Leu239Pro heterozygous knock-in mouse Mouse fails to recapitulate Heterozygous mice, the genotype equivalent to affected people, show no podocyte abnormality and normal kidney function, whereas heterozygous human carriers of the same substitution develop focal segmental glomerulosclerosis.

Show evidence (3 references)

PMID:29779709 SUPPORT Human Clinical

"Additionally, immunohistochemistry indicated reduced MAFB expression in the podocytes of patients."

Shows the molecular lesion reaching the podocyte in affected people.

PMID:29779709 SUPPORT Model Organism

"Lastly, podocytes in neonatal mice with p.Leu239Pro displayed impaired differentiation."

Direct demonstration in a knock-in mouse that the DURS3-spectrum allele impairs podocyte differentiation.

PMID:41898877 SUPPORT Model Organism

"Experimental studies in Mafb-deficient mouse models have demonstrated that MAFB is indispensable for podocyte differentiation, foot process formation, and maintenance of the glomerular filtration barrier, underscoring its critical role in renal development and function"

Summarizes the requirement for MAFB in building and maintaining the glomerular filtration barrier.

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

13

Ear 1

Sensorineural Hearing Impairment HP:0000407

Show evidence (2 references)

PMID:27181683 SUPPORT Human Clinical

"Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness."

Establishes deafness as part of the MAFB phenotype, and specifically with the dominant-negative allele rather than with every allele.

PMID:29779709 SUPPORT Human Clinical

"Hypoplasia of the abducens nerves and hearing impairment occurred in severely affected individuals."

Confirms hearing impairment in MAFB variant carriers and ties it to the severe end of the spectrum.

Genitourinary 1

Progression to End-Stage Kidney Disease Stage 5 chronic kidney disease HP:0003774

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"Within months, the patient progressed to end-stage kidney disease (ESKD), requiring initiation of maintenance hemodialysis, followed by renal transplantation."

Records progression to end-stage kidney disease in a MAFB bZIP-variant carrier.

Nervous System 1

Neurodevelopmental Involvement Global developmental delay HP:0001263

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"The proband exhibited CKD accompanied by congenital auricular anomalies, hearing loss, and neurodevelopmental delay."

Reports neurodevelopmental delay in a MAFB bZIP-variant carrier, with the authors noting that several features had not previously been associated with MAFB.

Other 10

Duane Anomaly HP:0009921

Show evidence (2 references)

PMID:27181683 SUPPORT Human Clinical

"Duane retraction syndrome (DRS) is a congenital eye-movement disorder defined by limited outward gaze and retraction of the eye on attempted inward gaze."

Defines the ocular phenotype in the report that established MAFB as a cause of it.

PMID:29779709 SUPPORT Human Clinical

"All four affected individuals developed FSGS and Duane Retraction Syndrome in their first to second decade of life, manifested as restricted abduction together with globe retraction and narrowed palpebral fissure on attempted adduction."

Documents the full Duane sign complex in MAFB p.Leu239Pro carriers from two unrelated families.

Abducens Nerve Hypoplasia or Aplasia Abnormal sixth cranial nerve morphology HP:0011348

Show evidence (1 reference)

PMID:29779709 SUPPORT Human Clinical

"Hypoplasia of the abducens nerves and hearing impairment occurred in severely affected individuals."

Reports abducens nerve hypoplasia directly in MAFB variant carriers.

Incomitant Strabismus in Primary Gaze HP:0025068

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"Many individuals with Duane syndrome have strabismus in primary gaze but can use a compensatory head turn to align the eyes, and thus can preserve binocular vision and avoid diplopia."

GeneReviews documents primary-gaze strabismus and the compensatory head turn in Duane syndrome, the clinical context in which the MAFB form presents.

Cochlear Malformation HP:0008554

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"Brain magnetic resonance imaging (MRI) at one year revealed cochlear aplasia with a bilateral common cavity configuration, without additional intracranial abnormalities."

Directly documents the cochlear malformation in a carrier of the MAFB p.Leu266Pro bZIP-domain variant.

Congenital Auricular Anomaly Abnormality of the outer ear HP:0000356

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"The proband exhibited CKD accompanied by congenital auricular anomalies, hearing loss, and neurodevelopmental delay."

Documents congenital auricular anomalies in a MAFB bZIP-variant carrier.

Compensatory Head Posture HP:0031705

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"Many individuals with Duane syndrome have strabismus in primary gaze but can use a compensatory head turn to align the eyes, and thus can preserve binocular vision and avoid diplopia."

GeneReviews documents the compensatory head turn and what it achieves.

Amblyopia HP:0000646

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"Individuals with Duane syndrome who lack binocular vision are at risk for amblyopia."

GeneReviews states the amblyopia risk and the subgroup it falls on.

Upshoot or Downshoot on Adduction

No ontology term is bound. HPO has no term for upshoot or downshoot on adduction, and the available alternatives searched (HP:0000496 Abnormality of eye movement, HP:0025586 Hypertropia) are respectively too broad to carry the meaning and describe a different sign. The finding is left as free text rather than annotated with a term that would be wrong in the export.

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"extraocular muscle surgery to address alignment in primary gaze, compensatory head posture, and upshoot or downshoot."

GeneReviews names upshoot and downshoot as findings requiring surgical management in Duane syndrome.

Focal Segmental Glomerulosclerosis HP:0000097

Show evidence (2 references)

PMID:29779709 SUPPORT Human Clinical

"To help define these roles, we studied two unrelated families with FSGS associated with Duane Retraction Syndrome, characterized by impaired horizontal eye movement due to cranial nerve malformation."

Establishes the co-occurrence of FSGS with the Duane anomaly in the MAFB families that define this arm.

PMID:41898877 SUPPORT Human Clinical

"Pathogenic variants in MAF BZIP Transcription Factor B (MAFB) (OMIM 608968) are primarily associated with two Mendelian phenotypes: multicentric carpotarsal osteolysis syndrome (MCTO; OMIM #166300), characterized by progressive skeletal osteolysis with possible renal involvement, and Duane..."

States explicitly that DRS3, the entity curated here, may co-occur with proteinuric kidney disease, which is why the renal arm is in scope.

Nephrotic-Range Proteinuria HP:0012593

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"An affected sibling presented with nephrotic-range proteinuria, Duane retraction syndrome (DRS) and neurodevelopmental involvement, while another family member had an isolated renal phenotype."

Documents nephrotic-range proteinuria in a carrier who also had the Duane anomaly, and records that a relative had renal disease alone.

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Genetic Associations

1

MAFB (Causative)

Gene: MAFB (large-MAF bZIP transcription factor) hgnc:6408 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (4 references)

PMID:27181683 SUPPORT Human Clinical

"Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness."

The founding report establishing MAFB as causative for this entity.

PMID:41898877 SUPPORT Human Clinical

"Notably, all missense MAFB variants previously associated with FSGS and DRS cluster within or adjacent to the DNA-binding region of the bZIP domain, supporting the hypothesis that impaired transcriptional regulation underlies the combined renal and neuro-ocular phenotype"

States that the DURS3-spectrum missense alleles cluster in the bZIP DNA-binding region.

PMID:24989131 SUPPORT Human Clinical

"All 5 mutations are within a 13 amino acid stretch of the transactivation domain."

Establishes the contrasting location of the MCTO alleles, the other MAFB Mendelian disease, in the N-terminal transactivation domain.

+ 1 more reference

Variants (3)

MAFB p.Leu239Pro Pathogenic

Gene: MAFB hgnc:6408 missense

A heterozygous leucine-to-proline substitution in the highly conserved DNA-binding region, found in two unrelated families whose four affected members all had both FSGS and the Duane anomaly. It reduces transactivation of a MARE-driven reporter, and structural modelling suggests it destabilizes the adjacent zinc finger. It is the allele modelled by the knock-in mouse.

Show evidence (2 references)

PMID:29779709 SUPPORT Human Clinical

"Genetic analyses revealed that affected individuals harbor a rare heterozygous substitution (p.Leu239Pro) in MAFB, a leucine zipper transcription factor."

Identifies the variant and its heterozygous state in the affected individuals.

PMID:29779709 SUPPORT Computational

"Structural modeling suggested that the p.Leu239Pro substitution in the DNA-binding domain possibly interferes with the stability of the adjacent zinc finger."

Structural prediction of how the substitution disrupts the DNA-binding module. The authors themselves hedge this as a possibility.

MAFB p.Leu266Pro (c.797T>C)

Gene: MAFB hgnc:6408 missense

A heterozygous bZIP-domain substitution segregating in an extended family with a strikingly variable phenotype spanning isolated renal disease, nephrotic-range proteinuria with the Duane anomaly, and end-stage kidney disease with cochlear aplasia, auricular anomalies, and neurodevelopmental delay.

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"Using Exome Sequencing (ES), a heterozygous variant, c.797T>C; p.(Leu266Pro) in the MAFB gene was identified in multiple affected family members."

Identifies the variant and its segregation across affected members of the family.

MAFB p.Glu223Lys Uncertain Significance

Gene: MAFB hgnc:6408 missense

A variant of uncertain significance recovered from sequencing of a large cohort with unsolved ocular congenital cranial dysinnervation disorders. Protein binding microarray showed it reduces or abolishes sequence-specific DNA binding, which supports but does not by itself establish pathogenicity.

Show evidence (1 reference)

PMID:40162949 SUPPORT In Vitro

"In addition, protein binding microarrays demonstrated reduced or abolished DNA binding of human variants of uncertain significance in known and novel sequence-derived transcription factors PHOX2A (p.(Trp137Cys)), MAFB (p.(Glu223Lys)), and OLIG2 (p.(Arg156Leu))."

Reports the measured loss of DNA binding, and is explicit that the variant is one of uncertain significance.

💊

Medical Actions

6

Extraocular Muscle (Strabismus) Surgery

Action: strabismus surgery Ontology label: Ophthalmologic Surgical Procedure NCIT:C15331

Recession or transposition of the extraocular muscles to improve alignment in the straight-ahead position, reduce a compensatory head turn, and address upshoot or downshoot. Surgery rebalances the eyes mechanically; it cannot restore abduction, because the abducens nerve that would drive it was never built. Management is the same as for Duane syndrome from any cause.

Mechanism Target:

MODULATES Horizontal Rectus Co-contraction and Globe Retraction — Recession or transposition mechanically rebalances the two horizontal recti that the aberrant oculomotor innervation makes fire together. It does not stop the co-contraction, because the miswiring is fixed from early development; it changes the forces the co-contraction produces, which is why it can improve alignment and the upshoot or downshoot while leaving abduction unrestored.

Show evidence (2 references)

PMID:20301369 SUPPORT Human Clinical

"extraocular muscle surgery to address alignment in primary gaze, compensatory head posture, and upshoot or downshoot."

Upshoot and downshoot are the direct expression of the co-contracting lateral rectus slipping over or under the globe, which is the node this link targets, and GeneReviews names them among the surgical indications.

PMID:40212284 SUPPORT Human Clinical

"Thirty-five patients who underwent strabismus surgery gained binocular vision and an improved appearance."

Outcome evidence that the surgery achieves what this link claims. Graded PARTIAL because it reports the clinical result in a general Duane cohort without measuring the co-contraction itself.

Target Phenotypes: Incomitant strabismus HP:0025068

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"extraocular muscle surgery to address alignment in primary gaze, compensatory head posture, and upshoot or downshoot."

GeneReviews specifies the surgical indications in Duane syndrome, which includes the MAFB-related form.

Amblyopia Therapy

Action: occlusion or penalization therapy for amblyopia Ontology label: Supportive Care NCIT:C15747

Occlusion or penalization of the better-seeing eye, to force use of the affected eye. This is the intervention with the narrowest window, because visual development cannot be recovered once it is over, and it is the reason the surveillance schedule is front-loaded into early childhood.

Target Phenotypes: Amblyopia HP:0000646

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"occlusion or penalization of the better-seeing eye for treatment of amblyopia"

GeneReviews specifies occlusion or penalization for amblyopia in Duane syndrome.

Optical Correction with Spectacles and Prisms

Action: optical correction Ontology label: Supportive Care NCIT:C15747

Spectacles or contact lenses to correct refractive error, and prism glasses to reduce the head turn in people with milder involvement. A device rather than a behavioural intervention, and separate from amblyopia therapy even though the two are usually prescribed together.

Target Phenotypes: Compensatory head posture HP:0031705

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"Spectacles or contact lenses for refractive error; occlusion or penalization of the better-seeing eye for treatment of amblyopia; prism glasses (usually in older individuals with mild involvement) to improve the compensatory head position"

GeneReviews lists refractive correction and prism glasses, and names the head position as what the prisms are for.

Ophthalmologic Surveillance for Amblyopia

Action: ophthalmologic surveillance Ontology label: Supportive Care NCIT:C15747

Not a treatment of the mechanism but the schedule that makes the treatable part treatable: three-to-six-monthly examinations through the first years of life, then annual or biannual review until binocular vision is established and the amblyopia risk has passed, and none in adulthood beyond ordinary public health guidance.

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"Ophthalmologic visits every three to six months during the first years of life to prevent, detect, and treat amblyopia; annual or biannual examinations once the presence of binocular vision and reduced risk for amblyopia is confirmed, and in all individuals older than age seven to 12; no..."

The GeneReviews surveillance schedule, quoted in full because the age thresholds are the operative content.

Cochlear Implantation

Action: cochlear implantation Ontology label: Surgical Procedure NCIT:C15329

For the profound sensorineural hearing loss of the inner-ear arm. It was performed bilaterally in a MAFB bZIP-variant carrier whose imaging showed cochlear aplasia with a common cavity. Note that a common-cavity cochlea is an unfavourable implant anatomy, so this reflects what was done in one reported case rather than an established outcome for this genotype. Milder hearing loss in this disease would ordinarily be managed with amplification instead, but no MAFB carrier fitted with hearing aids has been reported, so that is not curated here as a separate treatment.

Mechanism Target:

BYPASSES Impaired MAFB-Dependent Inner Ear Morphogenesis — An implant does not correct otic development. It routes around the malformed cochlea by stimulating the auditory nerve directly, which is why it can help even where the cochlea is aplastic with a common cavity, and why it is the only intervention in this entry that addresses the otic arm at all.

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"She subsequently underwent bilateral cochlear implantation."

The one reported instance of this intervention in a MAFB variant carrier, in an individual whose imaging showed cochlear aplasia with a common cavity. Graded PARTIAL because no outcome is reported, so it evidences that the route around the malformed cochlea was taken rather than that it succeeded.

Target Phenotypes: Sensorineural hearing impairment HP:0000407

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"She subsequently underwent bilateral cochlear implantation."

Records bilateral cochlear implantation in a MAFB variant carrier with profound pre-lingual hearing loss.

Renin-Angiotensin System Blockade for Proteinuria

Action: Pharmacotherapy NCIT:C15986

Agent: ACE inhibitor NCIT:C247

Angiotensin-converting enzyme inhibition to reduce proteinuria and slow decline in kidney function in carriers with the renal arm. In one reported carrier, kidney function remained stable over several years of treatment. This is antiproteinuric supportive care rather than a therapy directed at MAFB, and the evidence is a single family's clinical course.

Mechanism Target:

MODULATES Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure — ACE inhibition does not restore MAFB or repair the podocyte, but it lowers intraglomerular pressure across the damaged filtration barrier, which is what reduces protein loss and slows the decline in function. It acts on the consequences of the podocyte node rather than on its cause.

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"She was treated with angiotensin-converting enzyme (ACE) inhibitors for several years, during which her kidney function remained stable"

The only outcome evidence linking this treatment to the renal arm in a MAFB carrier. Graded PARTIAL because it is one uncontrolled patient course, not a demonstration that the mechanism node was modulated.

Target Phenotypes: Nephrotic range proteinuria HP:0012593

Show evidence (1 reference)

PMID:41898877 SUPPORT Human Clinical

"She was treated with angiotensin-converting enzyme (ACE) inhibitors for several years, during which her kidney function remained stable"

Documents ACE-inhibitor treatment with stable kidney function in one MAFB variant carrier. An uncontrolled single-patient course, hence PARTIAL.

🔬

Diagnosis

3

High-Resolution Cranial Nerve MRI

Dedicated thin-section MRI of the cranial nerves shows the abducens nerve to be absent or hypoplastic. This is what separates a congenital dysinnervation disorder from an acquired sixth-nerve palsy, where the nerve is present, and it is the imaging correlate of the founding lesion in this entry's pathograph. It does not distinguish the MAFB form from the other genetic or unsolved forms of Duane syndrome; only sequencing does that.

Show evidence (1 reference)

PMID:40212284 SUPPORT Human Clinical

"In 12 of the 14 patients with DRS1 and 9 of the 17 patients with DRS3, the abducens nerve was found to be absent in the MRI images, and in 4 of the patients with DRS2, the abducens nerve was detected as hypoplasia."

Demonstrates absent or hypoplastic abducens nerves on MRI in living patients. Note that DRS1, DRS2 and DRS3 in this cohort are the Huber CLINICAL types, not the numbered genetic loci; the paper's "DRS3" is Huber type III and is not this entity. The finding is cited here as evidence that the imaging detects the lesion, not as a genotype-specific frequency.

Ophthalmological Examination

The diagnosis of the Duane anomaly itself is clinical: an ophthalmologist observes the limitation of horizontal movement together with globe retraction and palpebral fissure narrowing on attempted adduction.

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"The diagnosis of Duane syndrome is usually made by an ophthalmologist based on clinical findings."

GeneReviews states that the Duane diagnosis is made clinically.

MAFB Molecular Genetic Testing

Sequencing MAFB, alongside CHN1 and SALL4, establishes the specific diagnosis. GeneReviews directs testing at those with a family history and at those whose motility pattern falls into Huber clinical type I or III. Because the MAFB-related form can carry hearing loss and proteinuric kidney disease, a molecular diagnosis here changes surveillance and not only counselling.

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"Molecular genetic testing for a pathogenic variant in CHN1, MAFB, or SALL4 is most appropriate for those with a positive family history of isolated Duane syndrome"

GeneReviews specifies when MAFB testing is indicated in Duane syndrome.

📊

Prevalence

1

Worldwide

Cases In Literature Not yet documented

No prevalence or incidence figure exists for molecularly confirmed MAFB-related Duane retraction syndrome. Reported cases amount to a handful of families. The general Duane syndrome population figures cannot be borrowed, because the overwhelming majority of Duane syndrome has no genetic diagnosis at all and only a small fraction of the solved cases are MAFB.

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"More than 98% of individuals with isolated Duane syndrome and no family history lack an identified genetic etiology."

Establishes that the molecularly solved fraction of Duane syndrome, of which MAFB is one of three genes, is very small, so no population rate can be assigned to this entity.

🔀

Differential Diagnoses

5

Conditions with similar clinical presentations that must be differentiated from Duane Retraction Syndrome 3 With Or Without Deafness:

Acquired Sixth Cranial Nerve Palsy

Overlapping Features The differential that matters most in practice, because it is the one with a treatable and sometimes dangerous cause behind it. An abduction deficit acquired later in life may signal raised intracranial pressure, a demyelinating lesion, microvascular ischaemia or a skull-base mass, none of which is compatible with a congenital dysinnervation disorder.

Distinguishing Features

Onset is acquired, not congenital and non-progressive.
No globe retraction and no palpebral fissure narrowing on adduction, because there is no aberrant oculomotor co-innervation to co-contract the horizontal recti.
The abducens nerve is present on high-resolution MRI, whereas it is absent or hypoplastic in this entity.
No family history and no MAFB variant.

Show evidence (1 reference)

PMID:20301369 SUPPORT Human Clinical

"Duane syndrome is a strabismus condition clinically characterized by congenital non-progressive limited horizontal eye movement accompanied by globe retraction which results in narrowing of the palpebral fissure."

Gives the two features that separate this entity from an acquired palsy: congenital non-progressive onset, and globe retraction from co-contraction.

Congenital Fibrosis of the Extraocular Muscles

Overlapping Features The other major ocular congenital cranial dysinnervation disorder. It shares the congenital, non-progressive, miswiring-based mechanism but involves different cranial nerves and a different gene set.

Distinguishing Features

Affects the oculomotor and trochlear nerves rather than the abducens, so the restriction is predominantly vertical with ptosis rather than horizontal.
Caused by KIF21A, PHOX2A, TUBB3 or other tubulin genes, not MAFB.
No associated deafness or proteinuric kidney disease.

Show evidence (1 reference)

PMID:41870107 SUPPORT Human Clinical

"Congenital fibrosis of the extraocular muscles (CFEOM), results from variants in KIF21A, PHOX2A, TUBB3, or other tubulin genes, and affects the oculomotor and trochlear nerves."

Gives the gene set and the affected nerves, which is what separates CFEOM from the abducens lesion of this entity.

Moebius Syndrome

Overlapping Features Also involves the abducens nerve, which is what makes it a genuine differential rather than a distant one, but it adds a facial nerve palsy and has no established genetic cause.

Distinguishing Features

Facial nerve palsy accompanies the abducens palsy, producing the characteristic mask-like facies absent from this entity.
No identified Mendelian cause; may be non-Mendelian, so a negative gene panel does not exclude it.
No deafness or renal involvement of the kind seen with MAFB bZIP variants.

Show evidence (1 reference)

PMID:41870107 SUPPORT Human Clinical

"Moebius syndrome, defined by abducens and facial nerve palsies, has no identified genetic cause and may result from non-Mendelian causes."

Gives the defining combination and the absence of a genetic cause, both of which separate it from this entity.

Horizontal Gaze Palsy with Progressive Scoliosis

Overlapping Features A brainstem axon-guidance disorder rather than a cranial nerve one, but it presents with a horizontal gaze abnormality and so enters the differential.

Distinguishing Features

Caused by ROBO3 loss of function, with failure of axonal midline crossing in the brainstem rather than failure of abducens nerve formation.
Progressive scoliosis accompanies the gaze palsy.
Horizontal gaze palsy is conjugate, not the unilateral or asymmetric abduction deficit with globe retraction seen here.

Show evidence (1 reference)

PMID:41870107 SUPPORT Human Clinical

"Horizontal gaze palsy with progressive scoliosis (HGPPS), caused by ROBO3 loss of function, arises from failure of axonal midline crossing in the brainstem."

Gives the gene and the distinct anatomical level of the lesion.

🔬

Clinical Trials

1

NCT03059420 NOT_APPLICABLE RECRUITING

A long-running observational cohort study at Boston Children's Hospital collecting genetic and phenotypic data on strabismus and congenital cranial dysinnervation disorders. It is a gene-discovery study, not an intervention trial; MAFB itself was identified through work of this kind. No interventional or disease-modifying trial exists for this entity.

Show evidence (1 reference)

clinicaltrials:NCT03059420 SUPPORT Other

"The purpose of this study is to identify genes associated with impaired development and function of the cranial nerves and brainstem, which may result in misalignment of the eyes (strabismus) and related conditions"

The registry record states the gene-discovery aim covering the congenital cranial dysinnervation disorders, of which this entity is one.

🐁

Animal Models

4

Mafb p.Leu239Pro homozygous knock-in mouse

A CRISPR-Cas9 knock-in mouse carrying the human DNA-binding-domain substitution. Homozygotes phenocopy the conventional Mafb-deficient mouse across the MAFB-dependent organs, which is what established that this leucine residue is required for MafB function rather than merely predicted to be.

Species

Mouse

Genotype

Mafb p.Leu239Pro homozygous knock-in (CRISPR-Cas9)

Publication

PMID:31882119

Pathograph links

MAFB Transcriptional Output Falls Below Its Developmental Threshold recapitulates fidelity: moderate Reproduces the molecular lesion itself, since it is the identical residue change found in affected people, and confirms that the substitution abolishes rather than merely alters MafB function.

Limitations: The functional equivalence to a null allele is demonstrated in the homozygote. Affected people are heterozygous, so the mouse establishes what the allele does to the protein rather than what one copy of it does to an organism.

Show evidence (1 reference)

PMID:31882119 SUPPORT Model Organism

"As a result, we found that the phenotype of Mafbmt/mt mouse was similar to that of the conventional Mafb deficient mouse."

Shows the knock-in allele behaves as a loss of MafB function across tissues, supporting the molecular node.

Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure recapitulates fidelity: moderate Newborn homozygotes show defective podocyte differentiation with impaired foot processes, the cellular lesion behind the renal arm.

Limitations: Homozygotes die within 48 hours of birth, so the model captures the developmental defect but not the slow progression to glomerulosclerosis and end-stage kidney disease seen in affected people.

Show evidence (1 reference)

PMID:37895232 SUPPORT Model Organism

"Mafb homozygous mutant mice died within 48 h after birth, and Mafb homozygous newborn mice showed defective differentiation of podocytes resulting from the impairment of foot processes."

Reports both the podocyte defect this link claims and the perinatal lethality that bounds it.

Mafb p.Leu239Pro heterozygous knock-in mouse

The dose-matched mouse: it carries one copy of the same substitution that affected people carry. It stays healthy, which is a genuine negative result rather than a missing experiment.

Species

Mouse

Genotype

Mafb p.Leu239Pro heterozygous knock-in (CRISPR-Cas9)

Publication

PMID:31882119

Pathograph links

Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure fails to recapitulate fidelity: low Heterozygous mice, the genotype equivalent to affected people, show no podocyte abnormality and normal kidney function, whereas heterozygous human carriers of the same substitution develop focal segmental glomerulosclerosis.

Limitations: A single copy of this allele is evidently below the threshold for disease in mouse but above it in human. Possible explanations include species differences in MafB dosage sensitivity, in the length of time the glomerulus must be maintained, or in modifier background, none of which have been tested. The practical consequence is that a null result in a heterozygous mouse cannot be used to argue against pathogenicity of a human MAFB allele.

Show evidence (1 reference)

PMID:37895232 SUPPORT Model Organism

"In contrast, Mafb heterozygous mutant mice could stay healthy without any abnormal podocyte formation or kidney function."

States the negative result directly: the dose-matched mouse does not develop the human phenotype.

Mafb-null mouse

Complete loss of Mafb removes the abducens motor nuclei outright and the lateral rectus is instead innervated by the oculomotor nerve, reproducing the human dysinnervation pathology.

Species

Mouse

Genotype

Mafb homozygous null

Publication

PMID:40162949

Pathograph links

Failure of Rhombomere 5 Patterning and Abducens Motor Neuron Specification recapitulates fidelity: high Absence of the sixth nerve motor nuclei, the cellular step this node asserts.

Limitations: A complete null is a deeper lesion than the heterozygous human alleles, and Mafb-null mice die soon after birth with hindbrain hypoplasia and respiratory failure, so the model cannot report on the postnatal course.

Show evidence (1 reference)

PMID:40162949 SUPPORT Model Organism

"Monoallelic MAFB LOF causes DRS in humans and absence of CN6 motor nuclei in mice, with secondary aberrant innervation by CN3 of the lateral rectus muscle, which is normally innervated by CN6."

States both the absent abducens nuclei and the secondary oculomotor misinnervation in the mouse.

mafba-null zebrafish

The zebrafish ortholog of MAFB. Loss of mafba severely malforms or abolishes the abducens motor nucleus, showing that the requirement is conserved well outside mammals and giving a tractable screening system for candidate cranial dysinnervation genes.

Species

Zebrafish

Genotype

mafba loss of function (germline null and G0 CRISPR/Cas9 knockout)

Publication

PMID:40162949

Pathograph links

Failure of Rhombomere 5 Patterning and Abducens Motor Neuron Specification recapitulates fidelity: moderate Absent or hypoplastic abducens motor nucleus on loss of the MAFB ortholog.

Limitations: Zebrafish carry duplicated MAFB paralogs and have two abducens motor nuclei per side rather than one, and the phenotype is scored in larvae rather than as an eye-movement disorder, so the anatomy maps onto human abducens development only approximately.

Show evidence (2 references)

PMID:40162949 SUPPORT Model Organism

"We first demonstrated the feasibility of the G0 screen by targeting known oCCDD genes phox2a and mafba. Approximately 70% to 90% of gene-targeted G0 zebrafish embryos recapitulated germline homozygous null-equivalent phenotypes."

The primary zebrafish study, establishing that targeting mafba reproduces the germline null abducens phenotype in the great majority of embryos.

+ 1 more reference

{ }

Source YAML

click to show

name: Duane Retraction Syndrome 3 With Or Without Deafness
creation_date: "2026-08-27T00:00:00Z"
category: Mendelian
synonyms:
- DURS3
- DRS3
- Duane retraction syndrome 3
- MAFB Duane retraction syndrome
- Duane retraction syndrome caused by mutation in MAFB
disease_term:
  preferred_term: Duane retraction syndrome 3 with or without deafness
  term:
    id: MONDO:0014880
    label: Duane retraction syndrome 3 with or without deafness
description: >-
  Duane retraction syndrome 3 (DURS3, OMIM 617041) is the MAFB-attributed member
  of the Duane retraction syndrome series. It is a congenital cranial
  dysinnervation disorder, not a disease of the extraocular muscles: the primary
  lesion is that the abducens (sixth cranial) nerve never forms properly and
  never fully innervates the lateral rectus, and the denervated muscle is then
  captured by a misrouted branch of the oculomotor (third cranial) nerve. Because
  the lateral rectus is thereafter wired to fire with the medial rectus, attempted
  adduction co-contracts both horizontal recti and drags the globe back into the
  orbit, while abduction stays deficient. The muscle itself is intact; the wiring
  diagram is wrong.


  MAFB is a single-exon basic leucine zipper (bZIP) transcription factor whose
  mouse ortholog kreisler specifies hindbrain rhombomere 5, the segment that
  gives rise to the abducens motor neurons. The variants that cause DURS3 sit in
  or beside the C-terminal bZIP DNA-binding region and reduce sequence-specific
  transcription, either by haploinsufficiency (heterozygous loss of function) or
  by a dominant-negative missense allele. Engle and colleagues, who identified
  the gene, framed the resulting allelic series as a threshold model: how far
  MAFB output falls determines how much of the MAFB-dependent developmental
  program fails, which is why an isolated eye-movement defect, an eye-movement
  defect plus deafness, and a broader syndrome can all arise from the same locus.


  The disease name understates the spectrum. The MONDO and OMIM labels name only
  deafness, but MAFB is also required for inner-ear morphogenesis and for
  podocyte differentiation, and bZIP-domain variants have been reported with
  focal segmental glomerulosclerosis, proteinuric kidney disease progressing to
  end-stage kidney disease, cochlear malformation, and neurodevelopmental
  involvement alongside the Duane anomaly. Expressivity is strikingly variable
  within a single family: in one reported kindred the sibling with the Duane
  anomaly had normal hearing while his sister, who had cochlear aplasia and
  developmental delay, could not be assessed ophthalmologically at all.


  DURS3 must be kept apart from two nearby things. First, it is not Huber
  clinical type 3 Duane syndrome; the "3" numbers the genetic locus, and a
  MAFB carrier may show Huber type 1. Second, MAFB carries a second, distinct
  Mendelian disease: multicentric carpotarsal osteolysis, caused by missense
  variants clustering in a short stretch of the N-terminal transactivation
  domain, which produces skeletal osteolysis and nephropathy but not the ocular
  motility defect. The genotype-phenotype split is domain-specific, and it is
  the cleanest available handle on which MAFB disease a new variant belongs to.
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0007473
      label: Duane retraction syndrome
    mapping_predicate: skos:broadMatch
    mapping_source: MONDO
    notes: >-
      The parent clinical entity, curated separately as `Duane_Retraction_Syndrome`
      and covering the CHN1 (DURS2) and SALL4 forms as well as the large majority
      of cases with no genetic diagnosis.
parents:
- congenital nervous system disorder
- hereditary neurological disease
- disorder of development or morphogenesis
inheritance:
- name: Autosomal dominant inheritance
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    Heterozygous MAFB variants are sufficient to cause disease, and affected
    parent-to-child transmission has been documented. Both inherited and de novo
    variants occur.
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Duane syndrome resulting from a CHN1, MAFB, or SALL4 pathogenic variant is
      inherited in an autosomal dominant manner.
    explanation: >-
      GeneReviews states that MAFB-related Duane syndrome is autosomal dominant.
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report on three heterozygous loss-of-function MAFB mutations
      causing DRS and a dominant-negative MAFB mutation causing DRS and deafness.
    explanation: >-
      The founding report establishes that single heterozygous MAFB alleles cause
      the disease, consistent with dominant inheritance.
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Each child of an individual with Duane syndrome resulting from an
      identified pathogenic variant has a 50% chance of inheriting the variant.
    explanation: >-
      Gives the recurrence risk that follows from dominant inheritance, which is
      the operative fact for counselling a MAFB carrier.
references:
- reference: PMID:20301369
  title: "Duane Syndrome."
  tags:
  - GeneReviews
- reference: PMID:27181683
  title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
- reference: PMID:29779709
  title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
- reference: PMID:41898877
  title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
- reference: PMID:40162949
  title: "Gene Identification for Ocular Congenital Cranial Motor Neuron Disorders Using Human Sequencing, Zebrafish Screening, and Protein Binding Microarrays."
- reference: PMID:31882119
  title: "Phenotypic analysis of mice carrying human-type MAFB p.Leu239Pro mutation."
- reference: PMID:10395784
  title: "The role of kreisler in segmentation during hindbrain development."
- reference: PMID:40212284
  title: "Etiology and clinical features of Han Chinese patients with Duane retraction syndrome."
- reference: PMID:41870107
  title: "Update on Congenital Cranial Dysinnervation Disorders (CCDDs)."
- reference: PMID:22387013
  title: "Multicentric carpotarsal osteolysis is caused by mutations clustering in the amino-terminal transcriptional activation domain of MAFB."
- reference: PMID:24989131
  title: "Multicentric carpotarsal osteolysis syndrome is caused by only a few domain-specific mutations in MAFB, a negative regulator of RANKL-induced osteoclastogenesis."
classifications:
  harrisons_chapter:
  - classification_value: NEUROLOGIC
  - classification_value: DISORDER_OF_EAR
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
pathophysiology:
- name: MAFB Transcriptional Output Falls Below Its Developmental Threshold
  biological_scale: MOLECULAR
  mechanism_confidence: ESTABLISHED
  description: >-
    MAFB is a single-exon large-MAF basic leucine zipper transcription factor
    that homodimerizes and binds MAF recognition elements (MAREs) to drive
    transcription of nearby target genes. The DURS3 alleles reduce that output
    by two routes. Heterozygous truncating and other loss-of-function alleles
    halve the dose; missense alleles in or beside the C-terminal DNA-binding
    region, of which p.Leu239Pro is the best characterized, leave a protein that
    cannot engage the MARE and can additionally poison the wild-type partner in
    the dimer, giving a dominant-negative allele. Engle and colleagues framed
    the resulting allelic series as a threshold model, in which the depth of the
    shortfall determines how much of the MAFB-dependent developmental program is
    lost and therefore how far the phenotype extends beyond the eye.
  molecular_functions:
  - preferred_term: sequence-specific MARE binding by the MAFB bZIP domain
    term:
      id: GO:0003700
      label: DNA-binding transcription factor activity
    modifier: DECREASED
  genetic_context:
    gene:
      preferred_term: MAFB
      term:
        id: hgnc:6408
        label: MAFB
    variant_origin: GERMLINE
    zygosity: HETEROZYGOUS
    functional_impact_category: LOSS_OF_FUNCTION
    description: >-
      Heterozygous germline MAFB alleles. Three loss-of-function alleles and one
      dominant-negative missense allele were reported in the founding cohort;
      subsequently reported DURS3-spectrum missense alleles cluster in or beside
      the bZIP DNA-binding region.
  evidence:
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report on three heterozygous loss-of-function MAFB mutations
      causing DRS and a dominant-negative MAFB mutation causing DRS and deafness.
    explanation: >-
      Establishes the two allelic classes, reduced dose and dominant-negative,
      that lower MAFB output in this disease.
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Using genotype-phenotype correlations in humans and Mafb-knockout mice, we
      propose a threshold model for variable loss of MAFB function.
    explanation: >-
      States the threshold model that this node encodes, in which the size of the
      shortfall in MAFB function sets the extent of the phenotype. The quoted
      sentence spans two evidence types, human genotype-phenotype correlation
      and Mafb-knockout mice. It is graded HUMAN_CLINICAL because the claim
      being supported is an allelic-series inference across affected people,
      which the mouse work extends rather than establishes; the mouse arm of the
      same paper is graded MODEL_ORGANISM where it is quoted separately on the
      abducens and reinnervation nodes.
  - reference: PMID:37895232
    reference_title: "Exploring Large MAF Transcription Factors: Functions, Pathology, and Mouse Models with Point Mutations."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      These four transcription factors are thought to be involved in the
      formation of homodimers and binding to DNA sequences called Maf
      recognition elements (MAREs) to stimulate the transcriptional activity of
      nearby target genes.
    explanation: >-
      Describes the normal molecular function that the DURS3 alleles degrade:
      MARE binding and target-gene transactivation by a MAF homodimer.
  - reference: PMID:37895232
    reference_title: "Exploring Large MAF Transcription Factors: Functions, Pathology, and Mouse Models with Point Mutations."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The mutation is a highly preserved leucine-to-proline substitution in the
      DNA-binding region of MAFB, rendering it incapable of binding to the MARE
      sequence.
    explanation: >-
      Identifies the molecular defect of the p.Leu239Pro allele as loss of MARE
      binding by the DNA-binding region.
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Luciferase assays with cultured monocytes indicated that the substitution
      significantly reduced transactivation of the F4/80 promoter, the known
      MAFB recognition element.
    explanation: >-
      Direct functional measurement that the DNA-binding-domain substitution
      lowers MAFB transactivation of a MARE-driven promoter.
  - reference: PMID:40162949
    reference_title: "Gene Identification for Ocular Congenital Cranial Motor Neuron Disorders Using Human Sequencing, Zebrafish Screening, and Protein Binding Microarrays."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In addition, protein binding microarrays demonstrated reduced or abolished
      DNA binding of human variants of uncertain significance in known and novel
      sequence-derived transcription factors PHOX2A (p.(Trp137Cys)), MAFB
      (p.(Glu223Lys)), and OLIG2 (p.(Arg156Leu)).
    explanation: >-
      An independent biophysical assay showing that a further MAFB variant from
      a cranial dysinnervation cohort loses sequence-specific DNA binding.
  downstream:
  - target: Failure of Rhombomere 5 Patterning and Abducens Motor Neuron Specification
    description: >-
      Reduced MAFB-driven transcription removes the segmental identity signal
      that the hindbrain uses to build the abducens motor neuron pool.
  - target: Impaired MAFB-Dependent Inner Ear Morphogenesis
    description: >-
      The same shortfall in MAFB output disrupts otic development, the parallel
      arm that produces the deafness named in the disease label.
  - target: Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure
    description: >-
      MAFB is separately required in the developing glomerulus, so DNA-binding
      domain alleles can additionally compromise the podocyte program.
- name: Failure of Rhombomere 5 Patterning and Abducens Motor Neuron Specification
  biological_scale: CELLULAR
  mechanism_confidence: ESTABLISHED
  description: >-
    The abducens motor neurons are born in hindbrain rhombomere 5, and the mouse
    MAFB ortholog kreisler is required for that segment to form at all. When
    MAFB function drops, rhombomere 5 identity is not established and the
    abducens motor neuron pool is not specified. Mafb-null mice lack the sixth
    nerve motor nuclei outright, and zebrafish lacking the mafba ortholog show
    absent or hypoplastic abducens nuclei, so the requirement is conserved
    across vertebrates.
  cell_types:
  - preferred_term: abducens motor neuron
    term:
      id: CL:0000100
      label: motor neuron
  biological_processes:
  - preferred_term: rhombomere 5 development
    term:
      id: GO:0021571
      label: rhombomere 5 development
    modifier: DECREASED
  - preferred_term: abducens motor neuron fate specification
    term:
      id: GO:0048665
      label: neuron fate specification
    modifier: DECREASED
  evidence:
  - reference: PMID:10395784
    reference_title: The role of kreisler in segmentation during hindbrain development.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Using Hox/lacZ transgenic mice as reporter lines and by analyzing
      Eph/ephrin expression, we have found that while r5 fails to form in these
      mice, r6 is present. This shows that kreisler has an early role in the
      formation of r5.
    explanation: >-
      Establishes that the mouse MAFB ortholog is required to form rhombomere 5,
      the hindbrain segment from which the abducens motor neurons arise.
  - reference: PMID:40162949
    reference_title: "Gene Identification for Ocular Congenital Cranial Motor Neuron Disorders Using Human Sequencing, Zebrafish Screening, and Protein Binding Microarrays."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Monoallelic MAFB LOF causes DRS in humans and absence of CN6 motor nuclei
      in mice, with secondary aberrant innervation by CN3 of the lateral rectus
      muscle, which is normally innervated by CN6.
    explanation: >-
      States that reduced MAFB function abolishes the abducens motor nuclei in
      mice, the cellular step this node models.
  - reference: PMID:37895232
    reference_title: "Exploring Large MAF Transcription Factors: Functions, Pathology, and Mouse Models with Point Mutations."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Therefore, mutations of MAFB impair the generation and/or inhibit the
      sustenance of abducens neurons, the inner ear, and podocytes in the
      kidneys
    explanation: >-
      A review of the MAF family summarizing that MAFB variants compromise the
      generation or maintenance of abducens neurons.
  downstream:
  - target: Abducens Nerve Hypoplasia and Failure to Innervate the Lateral Rectus
    description: >-
      Without a specified abducens motor neuron pool, the sixth nerve is
      hypoplastic or absent and never reaches its target muscle.
- name: Abducens Nerve Hypoplasia and Failure to Innervate the Lateral Rectus
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  description: >-
    The founding anatomical lesion is a hypoplastic or absent abducens nerve
    that fails to fully innervate the lateral rectus muscle. This is the
    dysinnervation event that defines the disease, and it is documented in
    affected people as well as in mice. The lateral rectus itself is a normal
    skeletal muscle at this point; what is missing is its motor supply.
  biological_processes:
  - preferred_term: abducens nerve development
    term:
      id: GO:0021560
      label: abducens nerve development
    modifier: DECREASED
  evidence:
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hypoplasia of the abducens nerves and hearing impairment occurred in
      severely affected individuals.
    explanation: >-
      Documents abducens nerve hypoplasia in MAFB variant carriers, and does so
      in the individuals at the severe end of the threshold, who also had
      hearing impairment.
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Thus, we present evidence that the primary cause of DRS is failure of the
      abducens nerve to fully innervate the lateral rectus muscle in early
      development.
    explanation: >-
      Names failed abducens innervation of the lateral rectus as the primary
      developmental cause, which is why this node and not an extraocular muscle
      defect is the root of the ocular arm.
  - reference: PMID:41870107
    reference_title: "Update on Congenital Cranial Dysinnervation Disorders (CCDDs)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Duane retraction syndrome, the most common CCDD, results from the absence
      of the abducens nerve and innervation of the lateral rectus by oculomotor
      nerve axons; causative genes include CHN1, MAFB, HOXA1, SALL4, and EBF3,
      although most cases do not have a genetic diagnosis.
    explanation: >-
      A current review placing MAFB among the causative genes and stating the
      absent-abducens-nerve mechanism this node encodes.
  downstream:
  - target: Aberrant Oculomotor Reinnervation of the Lateral Rectus
    description: >-
      The denervated lateral rectus is captured by a misrouted branch of the
      oculomotor nerve growing to nearby extraocular muscle targets.
- name: Aberrant Oculomotor Reinnervation of the Lateral Rectus
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  description: >-
    With no abducens input, the lateral rectus is secondarily innervated by
    aberrant branches of the oculomotor nerve that form at developmental
    decision regions close to the target extraocular muscles. This is a
    secondary consequence of the primary abducens failure rather than an
    independent guidance defect: selectively disrupting abducens development is
    by itself sufficient to produce the miswiring. The lateral rectus is
    thereafter yoked to the medial rectus rather than opposing it.
  cell_types:
  - preferred_term: aberrant oculomotor motor neuron
    term:
      id: CL:0000100
      label: motor neuron
  - preferred_term: lateral rectus muscle cell
    term:
      id: CL:0000188
      label: cell of skeletal muscle
  biological_processes:
  - preferred_term: ocular motor axon guidance
    term:
      id: GO:0008045
      label: motor neuron axon guidance
    modifier: ABNORMAL
  evidence:
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Moreover, we demonstrate that selectively disrupting abducens nerve
      development is sufficient to cause secondary innervation of the lateral
      rectus muscle by aberrant oculomotor nerve branches, which form at
      developmental decision regions close to target extraocular muscles.
    explanation: >-
      Shows experimentally that the aberrant oculomotor reinnervation is
      downstream of, and caused by, the abducens failure.
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Postmortem studies of DRS have reported abducens nerve hypoplasia and
      aberrant innervation of the lateral rectus muscle by the oculomotor nerve.
    explanation: >-
      Human postmortem pathology confirming that the lateral rectus receives
      oculomotor rather than abducens innervation.
  downstream:
  - target: Horizontal Rectus Co-contraction and Globe Retraction
    description: >-
      Shared oculomotor drive makes the lateral and medial recti contract
      together on attempted adduction.
- name: Horizontal Rectus Co-contraction and Globe Retraction
  biological_scale: ORGANISM
  mechanism_confidence: ESTABLISHED
  description: >-
    Because the lateral rectus now fires on the oculomotor command that also
    drives the medial rectus, attempted adduction contracts both horizontal
    recti at once. The opposed forces pull the globe backwards into the orbit,
    narrowing the palpebral fissure, while abduction remains deficient because
    the muscle no longer receives an abduction command. This synkinetic
    miswiring, not weakness or fibrosis of the muscle, is what a clinician sees
    at the bedside.
  cell_types:
  - preferred_term: horizontal rectus muscle cell
    term:
      id: CL:0000188
      label: cell of skeletal muscle
  evidence:
  - reference: PMID:40162949
    reference_title: "Gene Identification for Ocular Congenital Cranial Motor Neuron Disorders Using Human Sequencing, Zebrafish Screening, and Protein Binding Microarrays."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In DRS, CN6 maldevelopment causes limited abduction and variably limited
      adduction, and the globe retracts on attempted adduction because of
      synkinetic miswiring by CN3.
    explanation: >-
      Attributes the globe retraction directly to synkinetic oculomotor
      miswiring, the step this node models.
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      globe retraction occurs as a result of abnormal innervation of the lateral
      rectus muscle by the oculomotor nerve (cranial nerve III)
    explanation: >-
      GeneReviews states the same causal link between the aberrant innervation
      and the retraction.
- name: Impaired MAFB-Dependent Inner Ear Morphogenesis
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  description: >-
    MAFB is independently required for otic development, which is how the mouse
    gene was first found: the radiation-induced kreisler mutant was recognized
    by circling behavior caused by an inner-ear defect. In people, the
    dominant-negative allele that produces the deepest shortfall in MAFB
    function is the one reported with deafness, and imaging in a bZIP-variant
    carrier showed cochlear aplasia with a bilateral common cavity. This is a
    parallel arm of the same molecular lesion, not a consequence of the ocular
    defect.
  biological_processes:
  - preferred_term: inner ear morphogenesis
    term:
      id: GO:0042472
      label: inner ear morphogenesis
    modifier: DECREASED
  evidence:
  - reference: PMID:37895232
    reference_title: "Exploring Large MAF Transcription Factors: Functions, Pathology, and Mouse Models with Point Mutations."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Further study indicated that MafB plays an important role in segment
      formation in the hindbrain; in addition, the absence of MafB induces
      abnormal formation of the inner ear
    explanation: >-
      States the MAFB requirement for normal inner-ear formation that this node
      models, alongside its hindbrain segmentation role.
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report on three heterozygous loss-of-function MAFB mutations
      causing DRS and a dominant-negative MAFB mutation causing DRS and deafness.
    explanation: >-
      Ties the deafness specifically to the dominant-negative allele, which is
      the threshold-model prediction for this parallel arm.
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Brain magnetic resonance imaging (MRI) at one year revealed cochlear
      aplasia with a bilateral common cavity configuration, without additional
      intracranial abnormalities.
    explanation: >-
      Structural imaging in a MAFB bZIP-variant carrier showing a gross cochlear
      malformation, the anatomical form this arm can take.
- name: Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure
  biological_scale: CELLULAR
  mechanism_confidence: ESTABLISHED
  description: >-
    MAFB is also required in the developing glomerulus for podocyte
    differentiation and foot-process formation. Carriers of bZIP DNA-binding
    domain alleles have shown reduced podocyte MAFB by immunohistochemistry,
    and neonatal mice carrying the same substitution have poorly differentiated
    podocytes. The clinical consequence is focal segmental glomerulosclerosis
    and proteinuric kidney disease, which the MONDO and OMIM labels for this
    entity do not name but which is reported in DURS3-spectrum families. This
    arm is variably expressed and is not required for the diagnosis.
  cell_types:
  - preferred_term: glomerular podocyte
    term:
      id: CL:0000653
      label: podocyte
  biological_processes:
  - preferred_term: podocyte differentiation
    term:
      id: GO:0072112
      label: podocyte differentiation
    modifier: DECREASED
  evidence:
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Additionally, immunohistochemistry indicated reduced MAFB expression in
      the podocytes of patients.
    explanation: >-
      Shows the molecular lesion reaching the podocyte in affected people.
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Lastly, podocytes in neonatal mice with p.Leu239Pro displayed impaired
      differentiation.
    explanation: >-
      Direct demonstration in a knock-in mouse that the DURS3-spectrum allele
      impairs podocyte differentiation.
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Experimental studies in Mafb-deficient mouse models have demonstrated that
      MAFB is indispensable for podocyte differentiation, foot process
      formation, and maintenance of the glomerular filtration barrier,
      underscoring its critical role in renal development and function
    explanation: >-
      Summarizes the requirement for MAFB in building and maintaining the
      glomerular filtration barrier.
phenotypes:
- category: Eye
  name: Duane Anomaly
  description: >-
    The defining feature: congenital, non-progressive limitation of horizontal
    eye movement with retraction of the globe and narrowing of the palpebral
    fissure on attempted adduction. Involvement may be unilateral or bilateral.
  phenotype_term:
    preferred_term: Duane anomaly
    term:
      id: HP:0009921
      label: Duane anomaly
  diagnostic: true
  evidence:
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Duane retraction syndrome (DRS) is a congenital eye-movement disorder
      defined by limited outward gaze and retraction of the eye on attempted
      inward gaze.
    explanation: >-
      Defines the ocular phenotype in the report that established MAFB as a
      cause of it.
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All four affected individuals developed FSGS and Duane Retraction
      Syndrome in their first to second decade of life, manifested as restricted
      abduction together with globe retraction and narrowed palpebral fissure on
      attempted adduction.
    explanation: >-
      Documents the full Duane sign complex in MAFB p.Leu239Pro carriers from
      two unrelated families.
- category: Eye
  name: Abducens Nerve Hypoplasia or Aplasia
  description: >-
    Structural hypoplasia or absence of the sixth cranial nerve, the anatomical
    lesion underlying the motility pattern. It is demonstrable on dedicated
    high-resolution MRI of the cranial nerves and was documented in the more
    severely affected MAFB variant carriers.
  phenotype_term:
    preferred_term: Abducens nerve hypoplasia
    term:
      id: HP:0011348
      label: Abnormal sixth cranial nerve morphology
  evidence:
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hypoplasia of the abducens nerves and hearing impairment occurred in
      severely affected individuals.
    explanation: >-
      Reports abducens nerve hypoplasia directly in MAFB variant carriers.
- category: Eye
  name: Incomitant Strabismus in Primary Gaze
  description: >-
    Misalignment of the eyes in the straight-ahead position, most often
    esotropia. It is incomitant, meaning the angle changes with direction of
    gaze, which distinguishes it from common comitant childhood strabismus.
    Individuals who retain fusion typically adopt a compensatory head turn.
  phenotype_term:
    preferred_term: Incomitant strabismus
    term:
      id: HP:0025068
      label: Incomitant strabismus
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Many individuals with Duane syndrome have strabismus in primary gaze but
      can use a compensatory head turn to align the eyes, and thus can preserve
      binocular vision and avoid diplopia.
    explanation: >-
      GeneReviews documents primary-gaze strabismus and the compensatory head
      turn in Duane syndrome, the clinical context in which the MAFB form
      presents.
- category: Ear
  name: Sensorineural Hearing Impairment
  description: >-
    Hearing loss is the feature named by the "with or without deafness" clause.
    It tracks the depth of the MAFB shortfall rather than the ocular severity:
    it was reported with the dominant-negative allele and in the more severely
    affected members of bZIP-variant families, and can be profound and
    pre-lingual. It is not present in every carrier.
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  evidence:
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report on three heterozygous loss-of-function MAFB mutations
      causing DRS and a dominant-negative MAFB mutation causing DRS and deafness.
    explanation: >-
      Establishes deafness as part of the MAFB phenotype, and specifically with
      the dominant-negative allele rather than with every allele.
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hypoplasia of the abducens nerves and hearing impairment occurred in
      severely affected individuals.
    explanation: >-
      Confirms hearing impairment in MAFB variant carriers and ties it to the
      severe end of the spectrum.
- category: Ear
  name: Cochlear Malformation
  description: >-
    Gross structural maldevelopment of the cochlea, the anatomical correlate of
    the hearing loss. Cochlear aplasia with a bilateral common cavity was
    demonstrated on MRI in one MAFB bZIP-variant carrier, who went on to receive
    bilateral cochlear implants.
  phenotype_term:
    preferred_term: Cochlear aplasia with common cavity
    term:
      id: HP:0008554
      label: Cochlear malformation
  evidence:
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Brain magnetic resonance imaging (MRI) at one year revealed cochlear
      aplasia with a bilateral common cavity configuration, without additional
      intracranial abnormalities.
    explanation: >-
      Directly documents the cochlear malformation in a carrier of the MAFB
      p.Leu266Pro bZIP-domain variant.
- category: Head and Neck
  name: Congenital Auricular Anomaly
  description: >-
    Malformation of the external ear, reported together with the cochlear and
    renal findings in a carrier of a MAFB bZIP-domain variant, and prominent
    enough that the report naming it put "auricular" in its title. Small ears
    were also noted on that individual's dysmorphology examination. It sits with
    the otic arm of the disease rather than with the ocular one.
  phenotype_term:
    preferred_term: Congenital auricular anomaly
    term:
      id: HP:0000356
      label: Abnormality of the outer ear
  evidence:
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The proband exhibited CKD accompanied by congenital auricular anomalies,
      hearing loss, and neurodevelopmental delay.
    explanation: >-
      Documents congenital auricular anomalies in a MAFB bZIP-variant carrier.
- category: Eye
  name: Compensatory Head Posture
  description: >-
    A turn of the head that brings the eyes into the field where they are
    aligned. It is an adaptation rather than a lesion, and it is why some
    affected people preserve binocular vision and never develop diplopia. It is
    also a surgical indication in its own right, and abandoning it in later life
    is what makes a previously compensated strabismus become manifest.
  phenotype_term:
    preferred_term: Compensatory head turn
    term:
      id: HP:0031705
      label: Compensatory head posture
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Many individuals with Duane syndrome have strabismus in primary gaze but
      can use a compensatory head turn to align the eyes, and thus can preserve
      binocular vision and avoid diplopia.
    explanation: >-
      GeneReviews documents the compensatory head turn and what it achieves.
- category: Eye
  name: Amblyopia
  description: >-
    Failure of visual development in the affected eye. It is the one
    consequence of this disease that is preventable, which is why the
    surveillance schedule is built around detecting it, and the risk falls
    specifically on those who cannot achieve binocular alignment by turning
    their head.
  phenotype_term:
    preferred_term: Amblyopia
    term:
      id: HP:0000646
      label: Amblyopia
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Individuals with Duane syndrome who lack binocular vision are at risk for
      amblyopia.
    explanation: >-
      GeneReviews states the amblyopia risk and the subgroup it falls on.
- category: Eye
  name: Upshoot or Downshoot on Adduction
  description: >-
    A sudden vertical deviation of the eye as it is adducted, caused by the
    co-contracting lateral rectus slipping over or under the globe. It is a
    consequence of the same aberrant co-innervation that produces the
    retraction, and it is one of the specific things extraocular muscle surgery
    is done to address.
  notes: >-
    No ontology term is bound. HPO has no term for upshoot or downshoot on
    adduction, and the available alternatives searched (HP:0000496 Abnormality
    of eye movement, HP:0025586 Hypertropia) are respectively too broad to carry
    the meaning and describe a different sign. The finding is left as free text
    rather than annotated with a term that would be wrong in the export.
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      extraocular muscle surgery to address alignment in primary gaze,
      compensatory head posture, and upshoot or downshoot.
    explanation: >-
      GeneReviews names upshoot and downshoot as findings requiring surgical
      management in Duane syndrome.
- category: Genitourinary
  name: Focal Segmental Glomerulosclerosis
  description: >-
    Segmental scarring of the glomerular tuft on biopsy, the histological
    expression of the podocyte arm. All four affected individuals in the two
    families that defined the MAFB p.Leu239Pro phenotype had FSGS as well as
    the Duane anomaly. This feature is not named in the MONDO or OMIM label for
    this entity and is not present in every carrier.
  phenotype_term:
    preferred_term: Focal segmental glomerulosclerosis
    term:
      id: HP:0000097
      label: Focal segmental glomerulosclerosis
  evidence:
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      To help define these roles, we studied two unrelated families with FSGS
      associated with Duane Retraction Syndrome, characterized by impaired
      horizontal eye movement due to cranial nerve malformation.
    explanation: >-
      Establishes the co-occurrence of FSGS with the Duane anomaly in the
      MAFB families that define this arm.
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pathogenic variants in MAF BZIP Transcription Factor B (MAFB) (OMIM
      608968) are primarily associated with two Mendelian phenotypes:
      multicentric carpotarsal osteolysis syndrome (MCTO; OMIM #166300),
      characterized by progressive skeletal osteolysis with possible renal
      involvement, and Duane retraction syndrome 3 (DRS3; OMIM #617041), a
      congenital ocular cranial dysinnervation disorder that may co-occur with
      proteinuric kidney disease.
    explanation: >-
      States explicitly that DRS3, the entity curated here, may co-occur with
      proteinuric kidney disease, which is why the renal arm is in scope.
- category: Genitourinary
  name: Nephrotic-Range Proteinuria
  description: >-
    Heavy protein loss in the urine, the functional readout of the failing
    filtration barrier. It can be the presenting feature in a carrier whose
    ocular involvement is mild or unrecognized, and it can progress to
    end-stage kidney disease.
  phenotype_term:
    preferred_term: Nephrotic range proteinuria
    term:
      id: HP:0012593
      label: Nephrotic range proteinuria
  evidence:
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      An affected sibling presented with nephrotic-range proteinuria, Duane
      retraction syndrome (DRS) and neurodevelopmental involvement, while
      another family member had an isolated renal phenotype.
    explanation: >-
      Documents nephrotic-range proteinuria in a carrier who also had the Duane
      anomaly, and records that a relative had renal disease alone.
- category: Genitourinary
  name: Progression to End-Stage Kidney Disease
  description: >-
    The renal arm is not always indolent. In one reported family the proband
    progressed within months of the recognition of abnormal renal function to
    dialysis and then transplantation, and two of her relatives with the same
    variant also reached end-stage kidney disease.
  phenotype_term:
    preferred_term: End-stage kidney disease
    term:
      id: HP:0003774
      label: Stage 5 chronic kidney disease
  evidence:
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Within months, the patient progressed to end-stage kidney disease (ESKD),
      requiring initiation of maintenance hemodialysis, followed by renal
      transplantation.
    explanation: >-
      Records progression to end-stage kidney disease in a MAFB bZIP-variant
      carrier.
- category: Nervous System
  name: Neurodevelopmental Involvement
  description: >-
    Developmental delay, cognitive impairment, and behavioural features have
    been described in carriers of a MAFB bZIP-domain variant. This is a recently
    reported extension of the phenotype rather than an established core feature,
    and it is confounded in at least one reported individual by profound
    pre-lingual deafness.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The proband exhibited CKD accompanied by congenital auricular anomalies,
      hearing loss, and neurodevelopmental delay.
    explanation: >-
      Reports neurodevelopmental delay in a MAFB bZIP-variant carrier, with the
      authors noting that several features had not previously been associated
      with MAFB.
genetic:
- name: MAFB
  association: Causative
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: MAFB (large-MAF bZIP transcription factor)
    term:
      id: hgnc:6408
      label: MAFB
  notes: >-
    MAFB is the sole gene attributed to this entity. It is intronless, so the
    coding sequence is a single exon, and the protein has two functionally
    separable parts: an N-terminal transactivation domain and a C-terminal
    basic leucine zipper that carries both the DNA-binding basic region and the
    dimerization zipper. Which domain a variant lands in predicts which MAFB
    disease results. Variants in or beside the bZIP DNA-binding region give the
    DURS3 ocular, otic, and renal phenotype; variants clustered in a short
    stretch of the N-terminal transactivation domain give multicentric
    carpotarsal osteolysis instead, without the ocular motility defect.
  evidence:
  - reference: PMID:27181683
    reference_title: "Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report on three heterozygous loss-of-function MAFB mutations
      causing DRS and a dominant-negative MAFB mutation causing DRS and deafness.
    explanation: >-
      The founding report establishing MAFB as causative for this entity.
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Notably, all missense MAFB variants previously associated with FSGS and
      DRS cluster within or adjacent to the DNA-binding region of the bZIP
      domain, supporting the hypothesis that impaired transcriptional regulation
      underlies the combined renal and neuro-ocular phenotype
    explanation: >-
      States that the DURS3-spectrum missense alleles cluster in the bZIP
      DNA-binding region.
  - reference: PMID:24989131
    reference_title: "Multicentric carpotarsal osteolysis syndrome is caused by only a few domain-specific mutations in MAFB, a negative regulator of RANKL-induced osteoclastogenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All 5 mutations are within a 13 amino acid stretch of the transactivation
      domain.
    explanation: >-
      Establishes the contrasting location of the MCTO alleles, the other MAFB
      Mendelian disease, in the N-terminal transactivation domain.
  - reference: PMID:22387013
    reference_title: "Multicentric carpotarsal osteolysis is caused by mutations clustering in the amino-terminal transcriptional activation domain of MAFB."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Using exome capture and next-generation sequencing in five unrelated
      simplex cases of MCTO, we identified previously unreported missense
      mutations clustering within a 51 base pair region of the single exon of
      MAFB, validated by Sanger sequencing.
    explanation: >-
      The original report of the MCTO mutation cluster, independently
      establishing that the other MAFB disease occupies a different and very
      narrow part of the same single-exon gene.
  variants:
  - name: MAFB p.Leu239Pro
    description: >-
      A heterozygous leucine-to-proline substitution in the highly conserved
      DNA-binding region, found in two unrelated families whose four affected
      members all had both FSGS and the Duane anomaly. It reduces transactivation
      of a MARE-driven reporter, and structural modelling suggests it destabilizes
      the adjacent zinc finger. It is the allele modelled by the knock-in mouse.
    gene:
      preferred_term: MAFB
      term:
        id: hgnc:6408
        label: MAFB
    clinical_significance: PATHOGENIC
    type: missense
    evidence:
    - reference: PMID:29779709
      reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Genetic analyses revealed that affected individuals harbor a rare
        heterozygous substitution (p.Leu239Pro) in MAFB, a leucine zipper
        transcription factor.
      explanation: >-
        Identifies the variant and its heterozygous state in the affected
        individuals.
    - reference: PMID:29779709
      reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
      supports: SUPPORT
      evidence_source: COMPUTATIONAL
      snippet: >-
        Structural modeling suggested that the p.Leu239Pro substitution in the
        DNA-binding domain possibly interferes with the stability of the
        adjacent zinc finger.
      explanation: >-
        Structural prediction of how the substitution disrupts the DNA-binding
        module. The authors themselves hedge this as a possibility.
  - name: MAFB p.Leu266Pro (c.797T>C)
    description: >-
      A heterozygous bZIP-domain substitution segregating in an extended family
      with a strikingly variable phenotype spanning isolated renal disease,
      nephrotic-range proteinuria with the Duane anomaly, and end-stage kidney
      disease with cochlear aplasia, auricular anomalies, and neurodevelopmental
      delay.
    gene:
      preferred_term: MAFB
      term:
        id: hgnc:6408
        label: MAFB
    type: missense
    evidence:
    - reference: PMID:41898877
      reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Using Exome Sequencing (ES), a heterozygous variant, c.797T>C;
        p.(Leu266Pro) in the MAFB gene was identified in multiple affected
        family members.
      explanation: >-
        Identifies the variant and its segregation across affected members of
        the family.
  - name: MAFB p.Glu223Lys
    description: >-
      A variant of uncertain significance recovered from sequencing of a large
      cohort with unsolved ocular congenital cranial dysinnervation disorders.
      Protein binding microarray showed it reduces or abolishes sequence-specific
      DNA binding, which supports but does not by itself establish pathogenicity.
    gene:
      preferred_term: MAFB
      term:
        id: hgnc:6408
        label: MAFB
    clinical_significance: UNCERTAIN_SIGNIFICANCE
    type: missense
    evidence:
    - reference: PMID:40162949
      reference_title: "Gene Identification for Ocular Congenital Cranial Motor Neuron Disorders Using Human Sequencing, Zebrafish Screening, and Protein Binding Microarrays."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        In addition, protein binding microarrays demonstrated reduced or
        abolished DNA binding of human variants of uncertain significance in
        known and novel sequence-derived transcription factors PHOX2A
        (p.(Trp137Cys)), MAFB (p.(Glu223Lys)), and OLIG2 (p.(Arg156Leu)).
      explanation: >-
        Reports the measured loss of DNA binding, and is explicit that the
        variant is one of uncertain significance.
animal_models:
- name: Mafb p.Leu239Pro homozygous knock-in mouse
  species: Mouse
  genotype: Mafb p.Leu239Pro homozygous knock-in (CRISPR-Cas9)
  publication: PMID:31882119
  description: >-
    A CRISPR-Cas9 knock-in mouse carrying the human DNA-binding-domain
    substitution. Homozygotes phenocopy the conventional Mafb-deficient mouse
    across the MAFB-dependent organs, which is what established that this
    leucine residue is required for MafB function rather than merely predicted
    to be.
  modeled_mechanisms:
  - target: MAFB Transcriptional Output Falls Below Its Developmental Threshold
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Reproduces the molecular lesion itself, since it is the identical residue
      change found in affected people, and confirms that the substitution
      abolishes rather than merely alters MafB function.
    limitations: >-
      The functional equivalence to a null allele is demonstrated in the
      homozygote. Affected people are heterozygous, so the mouse establishes
      what the allele does to the protein rather than what one copy of it does
      to an organism.
    evidence:
    - reference: PMID:31882119
      reference_title: Phenotypic analysis of mice carrying human-type MAFB p.Leu239Pro mutation.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        As a result, we found that the phenotype of Mafbmt/mt mouse was similar
        to that of the conventional Mafb deficient mouse.
      explanation: >-
        Shows the knock-in allele behaves as a loss of MafB function across
        tissues, supporting the molecular node.
  - target: Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Newborn homozygotes show defective podocyte differentiation with impaired
      foot processes, the cellular lesion behind the renal arm.
    limitations: >-
      Homozygotes die within 48 hours of birth, so the model captures the
      developmental defect but not the slow progression to glomerulosclerosis
      and end-stage kidney disease seen in affected people.
    evidence:
    - reference: PMID:37895232
      reference_title: "Exploring Large MAF Transcription Factors: Functions, Pathology, and Mouse Models with Point Mutations."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Mafb homozygous mutant mice died within 48 h after birth, and Mafb
        homozygous newborn mice showed defective differentiation of podocytes
        resulting from the impairment of foot processes.
      explanation: >-
        Reports both the podocyte defect this link claims and the perinatal
        lethality that bounds it.
- name: Mafb p.Leu239Pro heterozygous knock-in mouse
  species: Mouse
  genotype: Mafb p.Leu239Pro heterozygous knock-in (CRISPR-Cas9)
  publication: PMID:31882119
  description: >-
    The dose-matched mouse: it carries one copy of the same substitution that
    affected people carry. It stays healthy, which is a genuine negative result
    rather than a missing experiment.
  modeled_mechanisms:
  - target: Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure
    relationship: FAILS_TO_RECAPITULATE
    fidelity: LOW
    description: >-
      Heterozygous mice, the genotype equivalent to affected people, show no
      podocyte abnormality and normal kidney function, whereas heterozygous
      human carriers of the same substitution develop focal segmental
      glomerulosclerosis.
    limitations: >-
      A single copy of this allele is evidently below the threshold for disease
      in mouse but above it in human. Possible explanations include species
      differences in MafB dosage sensitivity, in the length of time the
      glomerulus must be maintained, or in modifier background, none of which
      have been tested. The practical consequence is that a null result in a
      heterozygous mouse cannot be used to argue against pathogenicity of a
      human MAFB allele.
    evidence:
    - reference: PMID:37895232
      reference_title: "Exploring Large MAF Transcription Factors: Functions, Pathology, and Mouse Models with Point Mutations."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        In contrast, Mafb heterozygous mutant mice could stay healthy without
        any abnormal podocyte formation or kidney function.
      explanation: >-
        States the negative result directly: the dose-matched mouse does not
        develop the human phenotype.
- name: Mafb-null mouse
  species: Mouse
  genotype: Mafb homozygous null
  publication: PMID:40162949
  description: >-
    Complete loss of Mafb removes the abducens motor nuclei outright and the
    lateral rectus is instead innervated by the oculomotor nerve, reproducing
    the human dysinnervation pathology.
  modeled_mechanisms:
  - target: Failure of Rhombomere 5 Patterning and Abducens Motor Neuron Specification
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Absence of the sixth nerve motor nuclei, the cellular step this node
      asserts.
    limitations: >-
      A complete null is a deeper lesion than the heterozygous human alleles,
      and Mafb-null mice die soon after birth with hindbrain hypoplasia and
      respiratory failure, so the model cannot report on the postnatal course.
    evidence:
    - reference: PMID:40162949
      reference_title: "Gene Identification for Ocular Congenital Cranial Motor Neuron Disorders Using Human Sequencing, Zebrafish Screening, and Protein Binding Microarrays."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Monoallelic MAFB LOF causes DRS in humans and absence of CN6 motor
        nuclei in mice, with secondary aberrant innervation by CN3 of the
        lateral rectus muscle, which is normally innervated by CN6.
      explanation: >-
        States both the absent abducens nuclei and the secondary oculomotor
        misinnervation in the mouse.
- name: mafba-null zebrafish
  species: Zebrafish
  genotype: mafba loss of function (germline null and G0 CRISPR/Cas9 knockout)
  publication: PMID:40162949
  description: >-
    The zebrafish ortholog of MAFB. Loss of mafba severely malforms or abolishes
    the abducens motor nucleus, showing that the requirement is conserved well
    outside mammals and giving a tractable screening system for candidate
    cranial dysinnervation genes.
  modeled_mechanisms:
  - target: Failure of Rhombomere 5 Patterning and Abducens Motor Neuron Specification
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Absent or hypoplastic abducens motor nucleus on loss of the MAFB ortholog.
    limitations: >-
      Zebrafish carry duplicated MAFB paralogs and have two abducens motor
      nuclei per side rather than one, and the phenotype is scored in larvae
      rather than as an eye-movement disorder, so the anatomy maps onto human
      abducens development only approximately.
    evidence:
    - reference: PMID:40162949
      reference_title: "Gene Identification for Ocular Congenital Cranial Motor Neuron Disorders Using Human Sequencing, Zebrafish Screening, and Protein Binding Microarrays."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        We first demonstrated the feasibility of the G0 screen by targeting known
        oCCDD genes phox2a and mafba. Approximately 70% to 90% of gene-targeted
        G0 zebrafish embryos recapitulated germline homozygous null-equivalent
        phenotypes.
      explanation: >-
        The primary zebrafish study, establishing that targeting mafba
        reproduces the germline null abducens phenotype in the great majority of
        embryos.
    - reference: PMID:41898877
      reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        showed that disruption of the zebrafish MAFB ortholog, mafba, results in
        severe malformation or absence of the abducens cranial nerve (CN6) motor
        nucleus, supporting its evolutionarily conserved role in cranial motor
        neuron specification
      explanation: >-
        A secondary description naming the specific abducens-nucleus outcome,
        which the primary report describes in its figures rather than in a
        single quotable sentence.
treatments:
- name: Extraocular Muscle (Strabismus) Surgery
  description: >-
    Recession or transposition of the extraocular muscles to improve alignment
    in the straight-ahead position, reduce a compensatory head turn, and address
    upshoot or downshoot. Surgery rebalances the eyes mechanically; it cannot
    restore abduction, because the abducens nerve that would drive it was never
    built. Management is the same as for Duane syndrome from any cause.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: strabismus surgery
    term:
      id: NCIT:C15331
      label: Ophthalmologic Surgical Procedure
  target_phenotypes:
  - preferred_term: Incomitant strabismus
    term:
      id: HP:0025068
      label: Incomitant strabismus
  target_mechanisms:
  - target: Horizontal Rectus Co-contraction and Globe Retraction
    treatment_effect: MODULATES
    description: >-
      Recession or transposition mechanically rebalances the two horizontal
      recti that the aberrant oculomotor innervation makes fire together. It
      does not stop the co-contraction, because the miswiring is fixed from
      early development; it changes the forces the co-contraction produces,
      which is why it can improve alignment and the upshoot or downshoot while
      leaving abduction unrestored.
    evidence:
    - reference: PMID:20301369
      reference_title: "Duane Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        extraocular muscle surgery to address alignment in primary gaze,
        compensatory head posture, and upshoot or downshoot.
      explanation: >-
        Upshoot and downshoot are the direct expression of the co-contracting
        lateral rectus slipping over or under the globe, which is the node this
        link targets, and GeneReviews names them among the surgical
        indications.
    - reference: PMID:40212284
      reference_title: "Etiology and clinical features of Han Chinese patients with Duane retraction syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Thirty-five patients who underwent strabismus surgery gained binocular
        vision and an improved appearance.
      explanation: >-
        Outcome evidence that the surgery achieves what this link claims.
        Graded PARTIAL because it reports the clinical result in a general Duane
        cohort without measuring the co-contraction itself.
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      extraocular muscle surgery to address alignment in primary gaze,
      compensatory head posture, and upshoot or downshoot.
    explanation: >-
      GeneReviews specifies the surgical indications in Duane syndrome, which
      includes the MAFB-related form.
- name: Amblyopia Therapy
  description: >-
    Occlusion or penalization of the better-seeing eye, to force use of the
    affected eye. This is the intervention with the narrowest window, because
    visual development cannot be recovered once it is over, and it is the reason
    the surveillance schedule is front-loaded into early childhood.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: occlusion or penalization therapy for amblyopia
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Amblyopia
    term:
      id: HP:0000646
      label: Amblyopia
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      occlusion or penalization of the better-seeing eye for treatment of
      amblyopia
    explanation: >-
      GeneReviews specifies occlusion or penalization for amblyopia in Duane
      syndrome.
- name: Optical Correction with Spectacles and Prisms
  description: >-
    Spectacles or contact lenses to correct refractive error, and prism glasses
    to reduce the head turn in people with milder involvement. A device rather
    than a behavioural intervention, and separate from amblyopia therapy even
    though the two are usually prescribed together.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: optical correction
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Compensatory head posture
    term:
      id: HP:0031705
      label: Compensatory head posture
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Spectacles or contact lenses for refractive error; occlusion or
      penalization of the better-seeing eye for treatment of amblyopia; prism
      glasses (usually in older individuals with mild involvement) to improve
      the compensatory head position
    explanation: >-
      GeneReviews lists refractive correction and prism glasses, and names the
      head position as what the prisms are for.
- name: Ophthalmologic Surveillance for Amblyopia
  description: >-
    Not a treatment of the mechanism but the schedule that makes the treatable
    part treatable: three-to-six-monthly examinations through the first years of
    life, then annual or biannual review until binocular vision is established
    and the amblyopia risk has passed, and none in adulthood beyond ordinary
    public health guidance.
  treatment_term:
    preferred_term: ophthalmologic surveillance
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ophthalmologic visits every three to six months during the first years of
      life to prevent, detect, and treat amblyopia; annual or biannual
      examinations once the presence of binocular vision and reduced risk for
      amblyopia is confirmed, and in all individuals older than age seven to 12;
      no surveillance in adulthood beyond public health guidelines.
    explanation: >-
      The GeneReviews surveillance schedule, quoted in full because the age
      thresholds are the operative content.
  notes: >-
    Deliberately carries no `target_mechanisms`. Surveillance is a monitoring
    action, not a therapeutic one acting on a pathophysiology node.
- name: Cochlear Implantation
  description: >-
    For the profound sensorineural hearing loss of the inner-ear arm. It was
    performed bilaterally in a MAFB bZIP-variant carrier whose imaging showed
    cochlear aplasia with a common cavity. Note that a common-cavity cochlea is
    an unfavourable implant anatomy, so this reflects what was done in one
    reported case rather than an established outcome for this genotype. Milder
    hearing loss in this disease would ordinarily be managed with amplification
    instead, but no MAFB carrier fitted with hearing aids has been reported, so
    that is not curated here as a separate treatment.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: cochlear implantation
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_phenotypes:
  - preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  target_mechanisms:
  - target: Impaired MAFB-Dependent Inner Ear Morphogenesis
    treatment_effect: BYPASSES
    description: >-
      An implant does not correct otic development. It routes around the
      malformed cochlea by stimulating the auditory nerve directly, which is why
      it can help even where the cochlea is aplastic with a common cavity, and
      why it is the only intervention in this entry that addresses the otic arm
      at all.
    evidence:
    - reference: PMID:41898877
      reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        She subsequently underwent bilateral cochlear implantation.
      explanation: >-
        The one reported instance of this intervention in a MAFB variant
        carrier, in an individual whose imaging showed cochlear aplasia with a
        common cavity. Graded PARTIAL because no outcome is reported, so it
        evidences that the route around the malformed cochlea was taken rather
        than that it succeeded.
  evidence:
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      She subsequently underwent bilateral cochlear implantation.
    explanation: >-
      Records bilateral cochlear implantation in a MAFB variant carrier with
      profound pre-lingual hearing loss.
- name: Renin-Angiotensin System Blockade for Proteinuria
  description: >-
    Angiotensin-converting enzyme inhibition to reduce proteinuria and slow
    decline in kidney function in carriers with the renal arm. In one reported
    carrier, kidney function remained stable over several years of treatment.
    This is antiproteinuric supportive care rather than a therapy directed at
    MAFB, and the evidence is a single family's clinical course.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: ACE inhibitor
      term:
        id: NCIT:C247
        label: ACE Inhibitor
  target_phenotypes:
  - preferred_term: Nephrotic range proteinuria
    term:
      id: HP:0012593
      label: Nephrotic range proteinuria
  target_mechanisms:
  - target: Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure
    treatment_effect: MODULATES
    description: >-
      ACE inhibition does not restore MAFB or repair the podocyte, but it lowers
      intraglomerular pressure across the damaged filtration barrier, which is
      what reduces protein loss and slows the decline in function. It acts on
      the consequences of the podocyte node rather than on its cause.
    evidence:
    - reference: PMID:41898877
      reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        She was treated with angiotensin-converting enzyme (ACE) inhibitors for
        several years, during which her kidney function remained stable
      explanation: >-
        The only outcome evidence linking this treatment to the renal arm in a
        MAFB carrier. Graded PARTIAL because it is one uncontrolled patient
        course, not a demonstration that the mechanism node was modulated.
  evidence:
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      She was treated with angiotensin-converting enzyme (ACE) inhibitors for
      several years, during which her kidney function remained stable
    explanation: >-
      Documents ACE-inhibitor treatment with stable kidney function in one MAFB
      variant carrier. An uncontrolled single-patient course, hence PARTIAL.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: NOT_YET_DOCUMENTED
  notes: >-
    No prevalence or incidence figure exists for molecularly confirmed
    MAFB-related Duane retraction syndrome. Reported cases amount to a handful
    of families. The general Duane syndrome population figures cannot be
    borrowed, because the overwhelming majority of Duane syndrome has no genetic
    diagnosis at all and only a small fraction of the solved cases are MAFB.
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      More than 98% of individuals with isolated Duane syndrome and no family
      history lack an identified genetic etiology.
    explanation: >-
      Establishes that the molecularly solved fraction of Duane syndrome, of
      which MAFB is one of three genes, is very small, so no population rate can
      be assigned to this entity.
clinical_trials:
- name: NCT03059420
  phase: NOT_APPLICABLE
  status: RECRUITING
  description: >-
    A long-running observational cohort study at Boston Children's Hospital
    collecting genetic and phenotypic data on strabismus and congenital cranial
    dysinnervation disorders. It is a gene-discovery study, not an intervention
    trial; MAFB itself was identified through work of this kind. No
    interventional or disease-modifying trial exists for this entity.
  evidence:
  - reference: clinicaltrials:NCT03059420
    reference_title: "Genetic Studies of Strabismus, Congenital Cranial Dysinnervation Disorders (CCDDs), and Their Associated Anomalies"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The purpose of this study is to identify genes associated with impaired
      development and function of the cranial nerves and brainstem, which may
      result in misalignment of the eyes (strabismus) and related conditions
    explanation: >-
      The registry record states the gene-discovery aim covering the congenital
      cranial dysinnervation disorders, of which this entity is one.
diagnosis:
- name: High-Resolution Cranial Nerve MRI
  description: >-
    Dedicated thin-section MRI of the cranial nerves shows the abducens nerve to
    be absent or hypoplastic. This is what separates a congenital dysinnervation
    disorder from an acquired sixth-nerve palsy, where the nerve is present, and
    it is the imaging correlate of the founding lesion in this entry's
    pathograph. It does not distinguish the MAFB form from the other genetic or
    unsolved forms of Duane syndrome; only sequencing does that.
  evidence:
  - reference: PMID:40212284
    reference_title: "Etiology and clinical features of Han Chinese patients with Duane retraction syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In 12 of the 14 patients with DRS1 and 9 of the 17 patients with DRS3, the
      abducens nerve was found to be absent in the MRI images, and in 4 of the
      patients with DRS2, the abducens nerve was detected as hypoplasia.
    explanation: >-
      Demonstrates absent or hypoplastic abducens nerves on MRI in living
      patients. Note that DRS1, DRS2 and DRS3 in this cohort are the Huber
      CLINICAL types, not the numbered genetic loci; the paper's "DRS3" is Huber
      type III and is not this entity. The finding is cited here as evidence
      that the imaging detects the lesion, not as a genotype-specific frequency.
- name: Ophthalmological Examination
  description: >-
    The diagnosis of the Duane anomaly itself is clinical: an ophthalmologist
    observes the limitation of horizontal movement together with globe
    retraction and palpebral fissure narrowing on attempted adduction.
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The diagnosis of Duane syndrome is usually made by an ophthalmologist
      based on clinical findings.
    explanation: >-
      GeneReviews states that the Duane diagnosis is made clinically.
- name: MAFB Molecular Genetic Testing
  description: >-
    Sequencing MAFB, alongside CHN1 and SALL4, establishes the specific
    diagnosis. GeneReviews directs testing at those with a family history and at
    those whose motility pattern falls into Huber clinical type I or III.
    Because the MAFB-related form can carry hearing loss and proteinuric kidney
    disease, a molecular diagnosis here changes surveillance and not only
    counselling.
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Molecular genetic testing for a pathogenic variant in CHN1, MAFB, or
      SALL4 is most appropriate for those with a positive family history of
      isolated Duane syndrome
    explanation: >-
      GeneReviews specifies when MAFB testing is indicated in Duane syndrome.
differential_diagnoses:
- name: Acquired Sixth Cranial Nerve Palsy
  description: >-
    The differential that matters most in practice, because it is the one with a
    treatable and sometimes dangerous cause behind it. An abduction deficit
    acquired later in life may signal raised intracranial pressure, a
    demyelinating lesion, microvascular ischaemia or a skull-base mass, none of
    which is compatible with a congenital dysinnervation disorder.
  distinguishing_features:
  - Onset is acquired, not congenital and non-progressive.
  - No globe retraction and no palpebral fissure narrowing on adduction, because
    there is no aberrant oculomotor co-innervation to co-contract the horizontal
    recti.
  - The abducens nerve is present on high-resolution MRI, whereas it is absent
    or hypoplastic in this entity.
  - No family history and no MAFB variant.
  evidence:
  - reference: PMID:20301369
    reference_title: "Duane Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Duane syndrome is a strabismus condition clinically characterized by
      congenital non-progressive limited horizontal eye movement accompanied by
      globe retraction which results in narrowing of the palpebral fissure.
    explanation: >-
      Gives the two features that separate this entity from an acquired palsy:
      congenital non-progressive onset, and globe retraction from co-contraction.
- name: Congenital Fibrosis of the Extraocular Muscles
  description: >-
    The other major ocular congenital cranial dysinnervation disorder. It shares
    the congenital, non-progressive, miswiring-based mechanism but involves
    different cranial nerves and a different gene set.
  distinguishing_features:
  - Affects the oculomotor and trochlear nerves rather than the abducens, so the
    restriction is predominantly vertical with ptosis rather than horizontal.
  - Caused by KIF21A, PHOX2A, TUBB3 or other tubulin genes, not MAFB.
  - No associated deafness or proteinuric kidney disease.
  evidence:
  - reference: PMID:41870107
    reference_title: "Update on Congenital Cranial Dysinnervation Disorders (CCDDs)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Congenital fibrosis of the extraocular muscles (CFEOM), results from
      variants in KIF21A, PHOX2A, TUBB3, or other tubulin genes, and affects the
      oculomotor and trochlear nerves.
    explanation: >-
      Gives the gene set and the affected nerves, which is what separates CFEOM
      from the abducens lesion of this entity.
- name: Moebius Syndrome
  description: >-
    Also involves the abducens nerve, which is what makes it a genuine
    differential rather than a distant one, but it adds a facial nerve palsy and
    has no established genetic cause.
  distinguishing_features:
  - Facial nerve palsy accompanies the abducens palsy, producing the
    characteristic mask-like facies absent from this entity.
  - No identified Mendelian cause; may be non-Mendelian, so a negative gene
    panel does not exclude it.
  - No deafness or renal involvement of the kind seen with MAFB bZIP variants.
  evidence:
  - reference: PMID:41870107
    reference_title: "Update on Congenital Cranial Dysinnervation Disorders (CCDDs)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Moebius syndrome, defined by abducens and facial nerve palsies, has no
      identified genetic cause and may result from non-Mendelian causes.
    explanation: >-
      Gives the defining combination and the absence of a genetic cause, both of
      which separate it from this entity.
- name: Horizontal Gaze Palsy with Progressive Scoliosis
  description: >-
    A brainstem axon-guidance disorder rather than a cranial nerve one, but it
    presents with a horizontal gaze abnormality and so enters the differential.
  distinguishing_features:
  - Caused by ROBO3 loss of function, with failure of axonal midline crossing in
    the brainstem rather than failure of abducens nerve formation.
  - Progressive scoliosis accompanies the gaze palsy.
  - Horizontal gaze palsy is conjugate, not the unilateral or asymmetric
    abduction deficit with globe retraction seen here.
  evidence:
  - reference: PMID:41870107
    reference_title: "Update on Congenital Cranial Dysinnervation Disorders (CCDDs)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Horizontal gaze palsy with progressive scoliosis (HGPPS), caused by ROBO3
      loss of function, arises from failure of axonal midline crossing in the
      brainstem.
    explanation: >-
      Gives the gene and the distinct anatomical level of the lesion.
- name: CHN1- and SALL4-Related Duane Syndrome
  description: >-
    The genetic siblings, and the hardest differential of all, because the ocular
    phenotype can be indistinguishable. Only sequencing separates them, and the
    distinction matters because the extraocular surveillance differs.
  distinguishing_features:
  - CHN1 (DURS2) acts by gain of function in alpha2-chimaerin rather than loss of
    a transcription factor, and carries no deafness or renal involvement.
  - SALL4 produces the Duane-radial ray (Okihiro) spectrum, with radial ray limb
    anomalies absent from the MAFB form.
  - Neither carries the sensorineural hearing loss or proteinuric kidney disease
    that make a MAFB diagnosis change surveillance.
  evidence:
  - reference: PMID:41870107
    reference_title: "Update on Congenital Cranial Dysinnervation Disorders (CCDDs)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Duane retraction syndrome, the most common CCDD, results from the absence
      of the abducens nerve and innervation of the lateral rectus by oculomotor
      nerve axons; causative genes include CHN1, MAFB, HOXA1, SALL4, and EBF3,
      although most cases do not have a genetic diagnosis.
    explanation: >-
      Lists the genetic siblings sharing the identical mechanism, and records
      that most Duane syndrome has no genetic diagnosis at all, which is why the
      differential usually cannot be closed.
discussions:
- discussion_id: mafb_het_mouse_dose_mismatch
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Why does one copy of MAFB p.Leu239Pro cause focal segmental
    glomerulosclerosis and Duane retraction syndrome in a person, while the
    dose-matched heterozygous knock-in mouse stays healthy?
  attaches_to:
  - pathophysiology#Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure
  - pathophysiology#MAFB Transcriptional Output Falls Below Its Developmental Threshold
  rationale: >-
    The threshold model this entry is built on predicts that phenotype tracks
    the size of the shortfall in MAFB output. The mouse puts a number on where
    that threshold sits, and it is not in the same place in the two species: in
    the mouse, one mutant copy is tolerated and only the homozygote is affected,
    whereas in people one copy produces glomerulosclerosis and a cranial nerve
    that never formed. This is not a missing experiment; the heterozygote was
    examined and was normal. It matters for interpretation, because a negative
    result in a heterozygous mouse would otherwise look like evidence against a
    human MAFB allele being pathogenic, and it matters for the model, because it
    says the threshold is a property of the species and not of the protein.
    Candidate explanations include a difference in how much MafB the developing
    mouse glomerulus and hindbrain actually need, the far longer period over
    which a human glomerulus must be maintained, and modifier background. None
    has been tested.
  proposed_experiments:
  - experiment_id: mafb_het_dose_output_comparison
    name: Quantify MAFB target-gene output at matched heterozygous dose in both species
    description: >-
      Measure MARE-driven target-gene transcription in podocytes and in
      rhombomere-5-derived motor neurons from heterozygous mouse and from human
      induced pluripotent stem cell lines carrying the same substitution, to
      establish whether the two species differ in residual output or in
      sensitivity to the same residual output.
  evidence:
  - reference: PMID:37895232
    reference_title: "Exploring Large MAF Transcription Factors: Functions, Pathology, and Mouse Models with Point Mutations."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      In contrast, Mafb heterozygous mutant mice could stay healthy without any
      abnormal podocyte formation or kidney function.
    explanation: >-
      The negative result in the dose-matched mouse that creates the mismatch.
  - reference: PMID:29779709
    reference_title: "A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Genetic analyses revealed that affected individuals harbor a rare
      heterozygous substitution (p.Leu239Pro) in MAFB, a leucine zipper
      transcription factor.
    explanation: >-
      The human side of the mismatch: heterozygous carriers of the same
      substitution are affected.
- discussion_id: mafb_renal_arm_scope
  kind: OPEN_QUESTION
  status: OPEN
  prompt: >-
    Should proteinuric kidney disease be treated as part of Duane retraction
    syndrome 3, or as a separate MAFB-related renal disease that sometimes
    co-occurs with it?
  attaches_to:
  - pathophysiology#Impaired Podocyte Differentiation and Glomerular Filtration Barrier Failure
  rationale: >-
    The MONDO and OMIM labels for this entity name deafness and not kidney
    disease, yet every affected member of the two families that defined the
    p.Leu239Pro allele had focal segmental glomerulosclerosis, and a more
    recently reported family includes a carrier with an isolated renal
    phenotype and no ocular involvement at all. This entry curates the renal
    arm on the strength of a 2026 report stating that DRS3 may co-occur with
    proteinuric kidney disease, but the boundary is genuinely unsettled: the
    same bZIP alleles are also reported under headings such as
    MAFB-associated glomerulopathy. The practical question is whether a carrier
    with kidney disease alone should be recorded as having this entity. Until a
    nosological decision is made, this entry keeps the renal features and marks
    them as variable rather than defining.
  evidence:
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Duane retraction syndrome 3 (DRS3; OMIM #617041), a congenital ocular
      cranial dysinnervation disorder that may co-occur with proteinuric kidney
      disease.
    explanation: >-
      The statement this entry relies on to bring the renal arm inside the
      boundary of DRS3.
  - reference: PMID:41898877
    reference_title: "Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This patient denied a history of hearing impairment, ocular abnormalities,
      or neurodevelopmental disorders.
    explanation: >-
      A carrier of the same variant with kidney disease and no ocular, otic, or
      neurodevelopmental features, which is what makes the boundary question
      live.
notes: >-
  Entry-type decision: DISEASE. MONDO:0014880 is a leaf with no descendants and
  a single causal gene, so it is a curatable disease rather than a grouping. It
  is kept separate from the existing `Duane_Retraction_Syndrome` entry
  (MONDO:0007473) rather than folded in as a subtype, because the MAFB form
  carries mechanism and management that the clinical umbrella does not: a
  transcription-factor dosage lesion with parallel otic and renal arms, and a
  reason to screen hearing and urine that a CHN1 or genetically unsolved case
  does not have. The parent entry is cross-referenced under
  `mappings.mondo_mappings` with `skos:broadMatch`.


  Named-entity check: `just preflight-dr` on the falcon report returned PASS
  (MAFB mentioned 56 times against CHN1 twice; MONDO OMIM xref 617041). The two
  identity traps for this entity are recorded in the description: DURS3 is not
  Huber clinical type 3, and MAFB's other Mendelian disease, multicentric
  carpotarsal osteolysis, is a different domain of the same single-exon gene.


  Frequency values are deliberately absent from every phenotype. The literature
  on molecularly confirmed MAFB-related disease is a handful of families, and
  no denominator exists from which to derive a band. The one quantitative claim
  made anywhere in this entry is about the fraction of Duane syndrome overall
  that lacks a genetic diagnosis, which is cited.


  Orphanet has no entry keyed to this concept, so no ORPHA reference is cited.
  `just refresh-orphadata` is currently failing on a checksum mismatch in this
  repository, so the cached Orphanet corpus was not re-derived for this entry.
datasets: []

📚

References & Deep Research

References

11

PMID:20301369

Duane Syndrome.

No top-level findings curated for this source.

PMID:27181683

Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects.

No top-level findings curated for this source.

PMID:29779709

A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome.

No top-level findings curated for this source.

PMID:41898877

Broadening the Phenotypic Spectrum of MAFB-Related Disease: Renal, Auricular, Ocular, and Nervous System Involvement.

No top-level findings curated for this source.

PMID:40162949

Gene Identification for Ocular Congenital Cranial Motor Neuron Disorders Using Human Sequencing, Zebrafish Screening, and Protein Binding Microarrays.

No top-level findings curated for this source.

PMID:31882119

Phenotypic analysis of mice carrying human-type MAFB p.Leu239Pro mutation.

No top-level findings curated for this source.

PMID:10395784

The role of kreisler in segmentation during hindbrain development.

No top-level findings curated for this source.

PMID:40212284

Etiology and clinical features of Han Chinese patients with Duane retraction syndrome.

No top-level findings curated for this source.

PMID:41870107

Update on Congenital Cranial Dysinnervation Disorders (CCDDs).

No top-level findings curated for this source.

PMID:22387013

Multicentric carpotarsal osteolysis is caused by mutations clustering in the amino-terminal transcriptional activation domain of MAFB.

No top-level findings curated for this source.

PMID:24989131

Multicentric carpotarsal osteolysis syndrome is caused by only a few domain-specific mutations in MAFB, a negative regulator of RANKL-induced osteoclastogenesis.

No top-level findings curated for this source.

Deep Research

1

Falcon ▸

Disease Characteristics Research Template

Edison Scientific Literature 13 citations 2026-08-27T15:43:12.608920

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: Duane Retraction Syndrome 3 With Or Without Deafness
MONDO ID: (if available)
Category: Mendelian

Research Objectives

Please provide a comprehensive research report on Duane Retraction Syndrome 3 With Or Without Deafness 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

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.)

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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)

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

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

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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

Duane Retraction Syndrome 3 With or Without Deafness

Executive summary and evidence boundaries

Duane retraction syndrome 3 with or without deafness (DRS3) is an ultra-rare, congenital, Mendelian congenital cranial dysinnervation disorder (CCDD) caused by monoallelic MAFB dysfunction. Its core manifestation is Duane retraction syndrome—an incomitant strabismus caused by abnormal development of the abducens motor system and aberrant innervation of extraocular muscle—with variably present deafness or inner-ear malformation. The pivotal human-and-mouse report is Park et al., published May 12, 2016 online and June 2, 2016 in American Journal of Human Genetics (PMID 27181683; DOI/URL: https://doi.org/10.1016/j.ajhg.2016.03.023). Its title directly summarizes the principal conclusion: “Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects.” (NCT03059420 chunk 1)

The disease-specific literature remains very small. Consequently, exact phenotype frequencies, penetrance, incidence, life expectancy, and treatment-response rates for genetically confirmed MAFB-DRS3 are not established. Where this report uses broader Duane syndrome evidence, it is explicitly labeled general DRS evidence and should not be interpreted as a DRS3-specific frequency estimate.

The following table provides a compact knowledge-base summary.

Domain	Best-supported finding	Evidence scope/limitation
Disease identifier	Duane retraction syndrome 3 with or without deafness is represented in Open Targets as MONDO_0014880. (OpenTargets Search: Duane retraction syndrome 3-MAFB)	MONDO ID supported; avoid adding unsupported OMIM/Orphanet IDs here.
Causal gene	The disease is associated with MAFB (ENSG00000204103), a large MAF bZIP transcription factor. (OpenTargets Search: Duane retraction syndrome 3-MAFB, fujino2023exploringlargemaf pages 7-9)	Association is well supported genetically, but accessible sources here do not provide a full curated variant list.
Inheritance	Curated disease-target evidence labels the inheritance pattern as monoallelic autosomal. (OpenTargets Search: Duane retraction syndrome 3-MAFB)	Penetrance and expressivity are not fully quantified in the accessible evidence set.
Disease class	This is a congenital cranial dysinnervation disorder (CCDD) affecting ocular motility development. (NCT03059420 chunk 1, sanchez2023geneticsofstrabismus pages 1-2)	CCDD classification is strong; some broader DRS literature is not specific to MAFB-related DRS3.
Core ocular phenotype	General DRS is defined by abduction limitation, variable adduction deficit, globe retraction, and palpebral fissure narrowing on adduction; DRS is an incomitant strabismus. (derespinis1993duanesretractionsyndrome. pages 15-17, derespinis1993duanesretractionsyndrome. pages 10-11, murillocorrea2009clinicalfeaturesassociated pages 1-2)	These signs are well established for DRS overall; exact frequencies in MAFB-related DRS3 are not available here.
Auditory phenotype	DRS3 may occur with or without deafness; the key 2016 study title specifically cites inner-ear defects in humans and mice. (NCT03059420 chunk 1, OpenTargets Search: Duane retraction syndrome 3-MAFB)	Accessible evidence confirms the auditory/inner-ear association, but detailed audiologic frequencies and subtype breakdown are limited.
Developmental mechanism	Best-supported mechanism is loss of MAFB function disrupting development/survival of abducens neurons, causing aberrant extraocular muscle innervation and associated inner-ear defects. (NCT03059420 chunk 1, fujino2023exploringlargemafa pages 7-9, fujino2023exploringlargemaf pages 7-9, sanchez2023geneticsofstrabismus pages 1-2)	Mechanistic chain is supported by human genetics plus mouse data; exact embryonic cell/rhombomere details were not directly accessible.
Reported variant example	A reported heterozygous p.Leu239Pro MAFB variant lies in the DNA-binding region and was described as abolishing MARE binding; the same patient also had FSGS. (fujino2023exploringlargemafa pages 7-9, fujino2023exploringlargemaf pages 7-9)	Important genotype-phenotype example, but may represent overlap with renal phenotype rather than isolated ocular disease.
Animal model support	Mouse data support causality: studies cited report that loss of Mafb function causes Duane syndrome-like ocular innervation defects and inner-ear abnormalities; mutant mice with p.Leu239Pro show impaired podocyte differentiation. (NCT03059420 chunk 1, fujino2023exploringlargemaf pages 7-9)	Strong biologic support, but not a complete natural-history model for all human phenotypic variability.
Diagnosis	Diagnosis is primarily clinical ophthalmic assessment of incomitant strabismus/ocular motility pattern; MRI can support cranial nerve and extraocular muscle evaluation; genetic testing for MAFB is appropriate in syndromic/familial CCDD evaluation. (murillocorrea2009clinicalfeaturesassociated pages 1-2, NCT03059420 chunk 1)	No disease-specific biomarker or standardized MAFB-only diagnostic algorithm was identified.
Management	Current care is supportive/symptom-directed, using standard DRS approaches such as refractive/amblyopia management, monitoring, and selected strabismus surgery for abnormal head posture or primary-position deviation. (derespinis1993duanesretractionsyndrome. pages 27-28, derespinis1993duanesretractionsyndrome. pages 26-27, derespinis1993duanesretractionsyndrome. pages 15-17)	Evidence is extrapolated from general DRS management; MAFB-specific treatment studies were not found.
Disease-modifying therapy	No disease-modifying or gene-targeted therapy was identified for MAFB-related DRS3. (NCT03059420 chunk 1, fujino2023exploringlargemaf pages 7-9)	Current research emphasis is genetic discovery and mechanism, not interventional trials.
Ongoing research	A large observational genetics study of strabismus/CCDDs is recruiting (NCT03059420). (NCT03059420 chunk 1)	This is not a therapeutic trial; it supports gene discovery and phenotypic expansion.

Table: This table summarizes the most defensible disease-level facts for Duane retraction syndrome 3 with or without deafness using only accessible cited evidence. It is designed as a compact knowledge-base artifact that distinguishes strong findings from current evidence gaps.

1. Disease information

Definition

DRS3 is a congenital neurodevelopmental disorder of cranial motor innervation. Failure of normal abducens-neuron/nerve development and anomalous innervation of the lateral rectus produce limited horizontal eye movement, globe retraction, and narrowing of the palpebral fissure during attempted adduction. Hearing impairment is variably present, reflecting involvement of inner-ear development. Curated evidence associates only MAFB with the named MONDO entity. (OpenTargets Search: Duane retraction syndrome 3-MAFB, NCT03059420 chunk 1)

Identifiers and synonyms

MONDO: MONDO:0014880.
Causal target: MAFB; Ensembl ENSG00000204103; approved name MAF bZIP transcription factor B.
MeSH: the parent clinical disorder “Duane Retraction Syndrome” is D004370; the broader class “Congenital Cranial Dysinnervation Disorders” is D000093922. (NCT03059420 chunk 1, NCT03059420 chunk 2)
Common names: Duane retraction syndrome 3; DRS3; MAFB-related Duane syndrome; Duane syndrome with or without deafness; MAFB-related congenital cranial dysinnervation disorder.
A disease-specific ICD-10/ICD-11 code was not established in the retrieved evidence. In practice, coding generally occurs under Duane syndrome/strabismus, congenital ocular motility disorder, or cranial-nerve disorder rather than a molecularly specific MAFB code.
A disease-specific OMIM or Orphanet number could not be verified from the retrieved full-text evidence and is therefore not asserted here.

This report synthesizes aggregated disease-level resources, published pedigrees/cases, and model-organism studies, not individual EHR records. Open Targets integrates EVA, Gene2Phenotype, UniProt, ClinVar-like variant records, and literature evidence; it reports five to six evidence items depending on the displayed aggregation. (OpenTargets Search: Duane retraction syndrome 3-MAFB)

2. Etiology and risk/protective factors

Causal factor

The primary cause is a rare, germline, heterozygous/monoallelic pathogenic alteration affecting MAFB function. Open Targets assigns the MAFB–DRS3 association a score of 0.637 and identifies monoallelic autosomal inheritance; supporting literature includes PMID 27181683 and PMID 29779709. (OpenTargets Search: Duane retraction syndrome 3-MAFB)

MAFB is a large-MAF basic leucine-zipper transcription factor. Disease-associated alterations may truncate the protein or disrupt its DNA-binding function. A 2023 authoritative review states that the 2016 work identified MAFB as causal for Duane syndrome and concludes that MAFB mutations impair the generation or maintenance of abducens neurons and inner-ear structures. (fujino2023exploringlargemafa pages 7-9, fujino2023exploringlargemaf pages 7-9)

Risk factors

Genetic: carrying a pathogenic monoallelic MAFB variant is the established major risk factor. A positive family history raises prior probability, although de novo disease is biologically plausible and segregation-specific rates remain unquantified.
Environmental/lifestyle/infectious: no toxin, infection, diet, smoking, alcohol, occupation, or other exposure has been demonstrated to cause MAFB-DRS3.
Age/sex: congenital onset means age is not an acquired risk factor. No reliable DRS3-specific sex ratio exists.
General DRS only: approximately 90% of nonsyndromic DRS is sporadic and roughly 10% familial; these figures should not be assigned directly to MAFB-DRS3. (derespinis1993duanesretractionsyndrome. pages 26-27, murillocorrea2009clinicalfeaturesassociated pages 1-2)

Protective factors and gene–environment interaction

No genetic protective allele, environmental protective exposure, modifier gene, or replicated MAFB-specific gene–environment interaction is known. Environmental associations reported for common/comitant strabismus are not applicable evidence for this monogenic CCDD. There is likewise no evidence that diet, exercise, or avoidance of a particular exposure prevents DRS3 after conception.

3. Phenotypes

Core and associated manifestations

Abduction limitation/ophthalmoplegia — congenital clinical sign; usually stable but variable in severity. Suggested HPO: Abnormality of ocular abduction, External ophthalmoplegia.
Variable limitation of adduction — congenital sign; HPO: Abnormality of ocular adduction.
Globe retraction on adduction and palpebral-fissure narrowing on adduction — defining physical signs caused by horizontal rectus co-contraction; HPO suggestions: Globe retraction, Abnormal palpebral fissure.
Incomitant strabismus, including primary-position esotropia, orthotropia, or less commonly exotropia; HPO: Strabismus, Esotropia, Exotropia.
Upshoot/downshoot on adduction — variable sign due to anomalous innervation and/or mechanical leash effects; HPO: Abnormal extraocular movement.
Compensatory head turn — functional adaptation supporting binocular alignment; HPO: Abnormal head position.
Sensorineural hearing loss/deafness and inner-ear abnormality — optional rather than obligatory, as expressed by “with or without deafness”; HPO: Sensorineural hearing impairment, Deafness, Abnormal inner-ear morphology.

General DRS descriptions document severe abduction limitation, variable adduction limitation, retraction, fissure narrowing, and oblique upshoot/downshoot. Infants may initially show only abduction deficiency, with retraction becoming more evident later as the lateral rectus becomes less elastic or fibrotic. (derespinis1993duanesretractionsyndrome. pages 15-17, derespinis1993duanesretractionsyndrome. pages 10-11, murillocorrea2009clinicalfeaturesassociated pages 1-2)

Frequency and severity

No defensible percentage is available for any phenotype among molecularly confirmed MAFB-DRS3 cases. General DRS data report Huber type I in about 75%, type II around 7%, hypermetropia in approximately 71%, anisometropia greater than 1 diopter in 23%, and amblyopia in about 14%; these historical pooled values characterize DRS broadly, not DRS3. (derespinis1993duanesretractionsyndrome. pages 10-11)

Quality of life

DRS3-specific EQ-5D, SF-36, PROMIS, or disease-specific quality-of-life data are unavailable. Extrapolating cautiously from strabismus generally, misalignment can impair binocular vision, cause amblyopia, prompt compensatory head posture, and produce social or occupational discrimination and reduced quality of life. A 2023 review states that strabismus “leads to the disruption of binocular vision, amblyopia, social and occupational discrimination, and decreased quality of life.” (sanchez2023geneticsofstrabismus pages 1-2, sanchez2023geneticsofstrabismus pages 4-5)

No behavioral, psychiatric, or characteristic laboratory phenotype is established for DRS3 itself.

4. Genetic and molecular information

Gene and protein

Gene: MAFB.
Ensembl: ENSG00000204103.
Protein class: large-MAF basic leucine-zipper transcription factor.
Molecular function: sequence-specific DNA binding and transcriptional regulation at MAF-recognition elements (MAREs).
Suggested GO molecular-function terms: DNA-binding transcription factor activity; sequence-specific double-stranded DNA binding; protein heterodimerization activity.
Suggested GO cellular component: nucleus.

Pathogenic variants

Curated evidence encompasses missense and frameshift variants and absent gene products, but the retrieved material did not expose a complete, transcript-normalized variant roster or all current ACMG/AMP classifications. (OpenTargets Search: Duane retraction syndrome 3-MAFB)

A documented heterozygous example is MAFB p.Leu239Pro. This substitution lies in a highly conserved DNA-binding region and renders MAFB unable to bind the MARE sequence. The reported Japanese patient had Duane syndrome plus focal segmental glomerulosclerosis (FSGS), so the variant illustrates broader MAFB pleiotropy rather than a purely ocular phenotype. Mutant neonatal-mouse podocytes showed impaired differentiation. (fujino2023exploringlargemafa pages 7-9, fujino2023exploringlargemaf pages 7-9)

The review also mentions c.176C>T (p.Pro59Leu), but this is primarily associated with multicentric carpotarsal osteolysis, abnormal MAFB phosphorylation/degradation, and renal disease—not the canonical DRS3 phenotype—and should not be entered as a DRS3 variant without case-level evidence. (fujino2023exploringlargemaf pages 7-9)

The variants are presumed germline in this Mendelian condition. There is no evidence for a somatic DRS3 mechanism. Exact gnomAD/TOPMed allele frequencies were not available in the retrieved sources; pathogenic alleles are expected to be very rare, but no numerical frequency should be assigned without variant-specific database review.

Functional consequence

The best-supported disease model is loss of function or functional insufficiency, through truncation/absent product or impaired DNA binding. This differs from stabilization/gain-of-function mechanisms described for phosphorylation-site MAFB variants causing MCTO. (NCT03059420 chunk 1, fujino2023exploringlargemaf pages 7-9)

No validated modifier gene, disease-specific methylation signature, histone abnormality, repeat expansion, aneuploidy, recurrent translocation, or inversion is established. Large deletions involving MAFB remain technically detectable and should be considered when sequence testing is negative, but no recurrent DRS3 copy-number lesion was documented here.

5. Environmental information

No environmental, lifestyle, occupational, toxic, radiologic, dietary, or infectious cause is known. DRS3 is not infectious, transmissible, or zoonotic. Historical suggestions that general DRS may reflect a developmental insult during gestational weeks 4–8 do not establish a specific environmental cause and should not displace the demonstrated MAFB etiology. (derespinis1993duanesretractionsyndrome. pages 26-27)

6. Mechanism and pathophysiology

Causal chain

Upstream: germline monoallelic MAFB loss or impaired DNA binding → altered transcription during embryonic hindbrain and inner-ear development.

Intermediate: deficient generation, differentiation, or maintenance of abducens motor neurons/nerve and abnormal axonal targeting → absent or reduced normal sixth-nerve input to the lateral rectus, with aberrant extraocular-muscle innervation. In CCDDs generally, causal genes disturb either cranial motor-neuron differentiation or axon guidance. (NCT03059420 chunk 1, fujino2023exploringlargemaf pages 7-9, sanchez2023geneticsofstrabismus pages 1-2, sanchez2023geneticsofstrabismus pages 4-5)

Downstream ocular effect: inappropriate lateral-rectus activation during adduction and co-contraction with medial rectus → restricted abduction/adduction, globe retraction, fissure narrowing, upshoot/downshoot, strabismus, and compensatory head posture. Electromyographic evidence in general DRS demonstrates paradoxical lateral-rectus innervation during adduction. (derespinis1993duanesretractionsyndrome. pages 26-27, derespinis1993duanesretractionsyndrome. pages 15-17)

Downstream auditory effect: disturbed inner-ear development → variably present hearing loss/deafness. Park et al. demonstrated convergent human and mouse ocular and inner-ear abnormalities. (NCT03059420 chunk 1)

Relevant processes, cells, and structures

Suggested GO biological-process annotations include hindbrain development, cranial nerve development, motor neuron differentiation, axon guidance, neuron projection development, inner-ear development, DNA-templated transcription regulation, and extraocular skeletal muscle innervation. Suggested Cell Ontology concepts include motor neuron, more specifically abducens motor neuron, cranial motor neuron, inner-ear sensory epithelial cell/hair cell, and extraocular skeletal muscle cell. Some highly specific labels may require local ontology mapping if no exact CL class exists.

MAFB also regulates macrophage, podocyte, pancreas, parathyroid, thymus, epidermal, urethral, and lymphatic biology. These functions explain pleiotropic MAFB disorders but do not imply that immune, metabolic, or renal dysfunction is universal in DRS3. Mafb-null mice die after birth with hindbrain hypoplasia, respiratory and renal failure; thus complete loss has effects much broader than typical human monoallelic DRS3. (fujino2023exploringlargemaf pages 7-9)

No DRS3-specific inflammation, autoimmunity, oxidative stress, ischemia, fibrosis, metabolomic signature, lipidomic profile, proteomic biomarker, single-cell atlas, spatial-transcriptomic dataset, patient multi-omics analysis, organoid, or CRISPR-screen result was identified. The 2023 MAF review emphasizes that careful comparison of patients and mouse models is needed to uncover mechanisms and develop etiology-based therapies. (fujino2023exploringlargemafa pages 7-9, fujino2023exploringlargemaf pages 7-9)

7. Anatomical structures affected

Primary

Nervous system: embryonic hindbrain/brainstem abducens motor system; sixth cranial nerve.
Eye/orbit: lateral and medial rectus extraocular muscles and their innervation; ocular motor apparatus.
Auditory system: inner ear and potentially vestibulocochlear pathways in hearing-impaired cases.

Suggested UBERON annotations: hindbrain, brainstem, abducens nerve, eye, orbit, extraocular muscle, lateral rectus muscle, medial rectus muscle, inner ear, cochlea, and vestibulocochlear nerve. Suggested GO cellular-component annotations include nucleus, axon, growth cone, neuromuscular junction, and transcription-factor complex.

Secondary/variable

Renal podocytes and glomeruli may be involved in broader MAFB phenotypes, illustrated by p.Leu239Pro-associated FSGS, but renal disease is not established as a required feature of the named DRS3 entity. (fujino2023exploringlargemafa pages 7-9, fujino2023exploringlargemaf pages 7-9)

Lateralization

DRS can be unilateral, bilateral, or asymmetric. General DRS cohorts show a left-eye preference—approximately 72% among unilateral cases—and female predominance, but DRS3-specific lateralization and sex ratios are unknown. (derespinis1993duanesretractionsyndrome. pages 27-28, derespinis1993duanesretractionsyndrome. pages 26-27)

8. Temporal development

DRS3 is congenital, originating during embryogenesis. Recognition usually occurs in infancy or childhood when ocular motility, strabismus, or hearing is assessed. The disorder is chronic and lifelong rather than acute, episodic, inflammatory, or relapsing-remitting.

The underlying developmental wiring defect is generally stable. Apparent clinical retraction or mechanical restriction may become more obvious with age, while secondary amblyopia, refractive error, binocular-vision loss, or musculoskeletal consequences of persistent head posture can evolve. There are no validated molecular disease stages, remission pattern, or end-stage state. (derespinis1993duanesretractionsyndrome. pages 15-17)

The critical causal window is prenatal cranial-motor and inner-ear development. The main postnatal therapeutic window is early childhood, when refractive correction and amblyopia therapy can preserve visual development; surgery changes alignment and head posture but cannot reconstruct the embryonic wiring defect.

9. Inheritance and population

Inheritance

Curated evidence identifies monoallelic autosomal inheritance, clinically interpreted as autosomal dominant. (OpenTargets Search: Duane retraction syndrome 3-MAFB)

Penetrance is not adequately quantified. Variable expressivity is strongly suggested by “with or without deafness,” differences in ocular involvement, and the broader observation that relatives carrying CCDD mutations may show only some associated features without an ocular-motility disorder. (NCT03059420 chunk 1)

No evidence establishes anticipation, repeat instability, a founder mutation, sex-limited transmission, a consanguinity effect, or a population-specific carrier frequency. Germline mosaicism has not been quantified; it remains a general counseling possibility after an apparently de novo variant.

Epidemiology

No prevalence or incidence estimate exists for molecularly confirmed MAFB-DRS3. It is substantially rarer than DRS overall. General DRS has been estimated at approximately 1 in 1,000 and accounts for up to 4% of strabismus cases, but these should not be entered as DRS3 prevalence. Approximately 90% of nonsyndromic DRS is sporadic, with only about 10% familial. (murillocorrea2009clinicalfeaturesassociated pages 1-2)

No reliable ethnic, geographic, age-distribution, or sex-ratio enrichment has been demonstrated for MAFB-DRS3.

10. Diagnostics

Clinical diagnosis

Evaluation should include:

Pediatric ophthalmic/orthoptic examination: monocular and binocular ductions, primary-position alignment, globe retraction, fissure narrowing, upshoot/downshoot, compensatory head posture, visual acuity, cycloplegic refraction, stereopsis, and amblyopia assessment.
Audiologic testing: age-appropriate otoacoustic emissions, auditory brainstem response, and behavioral pure-tone audiometry, because hearing loss is variably present.
Focused examination for additional congenital anomalies and renal assessment when phenotype or genotype suggests broader MAFB involvement.

General DRS diagnosis is principally clinical. Huber type I has limited abduction, type II predominantly limited adduction, and type III limitation of both; however, molecular DRS3 should be classified genetically and phenotypically rather than inferred from Huber type alone. (derespinis1993duanesretractionsyndrome. pages 15-17, derespinis1993duanesretractionsyndrome. pages 10-11)

Imaging and electrophysiology

High-resolution MRI of the brainstem, cisternal cranial nerves, internal auditory canals, inner ear, orbits, and extraocular muscles can document absent/hypoplastic nerves or structural ear abnormalities and exclude acquired lesions. MRI abnormalities in general DRS can include hypoplastic ocular motor nerves or small innervated muscles. Imaging is supportive, not required in every classic uncomplicated case. (derespinis1993duanesretractionsyndrome. pages 27-28, murillocorrea2009clinicalfeaturesassociated pages 1-2)

Electromyography can demonstrate anomalous lateral-rectus activation but is invasive and rarely needed clinically. There is no diagnostic blood chemistry, urine analyte, tissue biopsy, circulating biomarker, proteomic marker, or metabolomic signature.

Genetic testing strategy

Use an ocular-motility/CCDD panel including MAFB, CHN1, SALL4, HOXA1, KIF21A, TUBB3, and other phenotype-appropriate genes.
Alternatively, sequence MAFB directly when DRS plus hearing loss/inner-ear malformation strongly indicates DRS3.
Ensure copy-number analysis is included; if panel testing is negative, trio WES or preferably WGS can identify coding, splice, structural, or regulatory variants.
Confirm candidate variants and segregation by orthogonal testing when appropriate.
CMA is useful when multiple congenital anomalies suggest a genomic imbalance. Karyotyping/FISH is reserved for suspected cytogenetic rearrangement.
Mitochondrial DNA, repeat-expansion, epigenomic, liquid-biopsy, proteomic, and metabolomic tests have no established role.

Differential diagnosis

Important alternatives are isolated congenital sixth-nerve palsy; CHN1-related DRS; SALL4-related Duane-radial ray/Okihiro syndrome; HOXA1-related brainstem dysgenesis; Moebius syndrome; congenital fibrosis of extraocular muscles; horizontal gaze palsy with progressive scoliosis; Brown syndrome; restrictive orbital disease; congenital hearing-loss syndromes; and acquired retraction from trauma, thyroid eye disease, inflammation, tumor, or prior surgery. Acquired conditions are distinguished by later onset, diplopia, pain/proptosis, trauma or surgery history, progressive course, or orbital imaging abnormalities. (derespinis1993duanesretractionsyndrome. pages 15-17, NCT03059420 chunk 1)

Screening

Population or newborn genomic screening is not established. Cascade testing is appropriate after identifying a familial pathogenic variant. Audiologic screening should not be omitted in confirmed or suspected DRS3. Prenatal or preimplantation testing is technically possible once the familial variant is known, following genetic counseling.

11. Outcome and prognosis

No DRS3-specific mortality, five- or ten-year survival, or life-expectancy deficit is documented. Isolated ocular/auditory disease is not expected to shorten survival. Complete Mafb loss is lethal in mice, but that is not an appropriate prognosis model for heterozygous human DRS3. (fujino2023exploringlargemaf pages 7-9)

Principal morbidity includes restricted gaze, anomalous head posture, primary-position misalignment, amblyopia, impaired stereopsis/binocular field, hearing-related communication difficulty, and psychosocial burden. General DRS is described as congenital and nonthreatening; most patients preserve useful vision and many maintain normal stereopsis through compensatory head posture. (derespinis1993duanesretractionsyndrome. pages 27-28, derespinis1993duanesretractionsyndrome. pages 15-17)

The neural dysinnervation itself does not recover. Refractive error and amblyopia are treatable, hearing can be rehabilitated, and alignment/head posture may improve after appropriate surgery. Prognosis depends on bilateral involvement, primary-gaze deviation, amblyopia, severity of head posture, hearing impairment, and additional MAFB-associated organ disease. No validated prognostic molecular biomarker exists.

12. Treatment and current applications

There is no approved pharmacologic, gene, RNA, cell, CRISPR, immunologic, or other disease-modifying therapy for MAFB-DRS3. Management is multidisciplinary and phenotype-directed.

Ophthalmic care

Observation when alignment in primary gaze, binocular function, and head posture are acceptable.
Spectacle correction of refractive error.
Standard amblyopia treatment—optical correction, patching, or atropine penalization as clinically indicated.
Prisms may help selected small primary-position deviations but cannot restore abduction.
Strabismus surgery is considered for a substantial compensatory head turn, cosmetically/functionally significant primary-position deviation, severe globe retraction, or disfiguring upshoot/downshoot. General DRS procedures include medial or lateral rectus recession, vertical-rectus or superior-rectus transposition, and lateral-rectus Y-splitting for marked up/downshoot. Surgery must be individualized to alignment, forced duction, innervation pattern, and binocular function. Historical review supports surgery for significant head posture or noticeable deviation and describes recession, Y-splitting, adjustable sutures, and botulinum approaches. (derespinis1993duanesretractionsyndrome. pages 27-28, derespinis1993duanesretractionsyndrome. pages 26-27)

Suggested NCIT concepts: Strabismus Surgery, Extraocular Muscle Recession, Muscle Transposition Procedure, Corrective Lens Therapy, Occlusion Therapy, Audiologic Rehabilitation, Hearing Aid, and Cochlear Implantation. Exact NCIT identifiers should be validated against the current NCI Thesaurus release before database ingestion.

Hearing management

ENT/audiology surveillance; hearing aids for aidable loss; communication and educational support; and cochlear-implant evaluation for severe/profound sensorineural loss where cochlear and cochlear-nerve anatomy and physiology permit. No DRS3-specific response rate is available.

Trials and recent implementation

NCT03059420, “Genetic Studies of Strabismus, Congenital Cranial Dysinnervation Disorders (CCDDs), and Their Associated Anomalies,” is a recruiting Boston Children’s Hospital observational cohort, started February 1, 2004, with estimated enrollment of 20,000 and estimated completion in 2030. It accepts participants from one day of age onward and retains DNA-containing blood, saliva, or discarded tissue. Its purpose is gene discovery and functional characterization, not treatment. ClinicalTrials.gov: https://clinicaltrials.gov/study/NCT03059420. Status was verified February 2026. (NCT03059420 chunk 1)

No interventional DRS3 trial or genotype-guided pharmacotherapy was identified.

13. Prevention

Primary prevention

No vaccine, medication, lifestyle change, environmental avoidance strategy, or prophylactic procedure prevents a pathogenic MAFB developmental disorder. Immunization and infectious-disease measures are not disease-specific.

Secondary prevention

Early recognition can prevent avoidable consequences rather than disease occurrence: prompt cycloplegic refraction and amblyopia management; audiologic assessment; surveillance of visual development and head posture; and evaluation for associated anomalies.

Genetic prevention and counseling

Offer clinical genetics assessment, segregation testing, cascade testing of at-risk relatives, and reproductive counseling. Under autosomal-dominant inheritance, a heterozygous affected individual generally has a 50% transmission probability per pregnancy, although phenotypic severity and deafness cannot be predicted reliably because expressivity is variable. Prenatal diagnosis and preimplantation genetic testing are possible after identification of the familial variant. Apparently de novo cases have low but nonzero recurrence risk because parental germline mosaicism cannot be excluded.

Tertiary prevention

Treat amblyopia before visual maturation, correct refractive error, rehabilitate hearing early, monitor educational/language development, and address sustained abnormal head posture to limit secondary disability. There is no population screening program specific to DRS3.

14. Other species and natural disease

The key comparative species is the laboratory mouse, Mus musculus (NCBI Taxonomy 10090), carrying the ortholog Mafb. Human is Homo sapiens (Taxonomy 9606). MAFB’s developmental transcriptional role is evolutionarily conserved sufficiently for mouse loss-of-function to reproduce ocular motor and inner-ear abnormalities relevant to human disease. (NCT03059420 chunk 1, fujino2023exploringlargemaf pages 7-9)

No naturally occurring veterinary DRS3 attributable to Mafb, affected breed, VBO identifier, wildlife reservoir, cross-species transmission, or zoonotic risk was identified. This is an inherited developmental disorder, not a transmissible disease.

15. Model organisms and experimental systems

Mouse models

Park et al. provided the central disease model: loss of Mafb function in mice causes Duane-like abnormal extraocular-muscle innervation and inner-ear defects, offering strong cross-species support for causal inference from the human variants. (NCT03059420 chunk 1)

Broader Mafb knockout and knock-in models demonstrate hindbrain, respiratory, kidney, parathyroid, pancreatic, macrophage, and developmental functions. Homozygous Mafb-GFP knock-in/knockout mice die immediately after birth with hindbrain hypoplasia plus respiratory and renal failure. CRISPR-generated p.Leu239Pro models support loss of DNA-binding function and abnormal podocyte differentiation. (fujino2023exploringlargemaf pages 7-9)

Recapitulation and limitations

Strengths: direct manipulation of the ortholog; replication of ocular-innervation and inner-ear phenotypes; access to embryonic axon trajectories and tissue histology; mechanistic separation of MAFB dosage and domain-specific effects.

Limitations: homozygous null lethality and multisystem disease exceed the typical heterozygous human phenotype; mouse eye-movement behavior and hearing anatomy are not identical to humans; penetrance and clinical variability may not map directly; p.Leu239Pro models also emphasize renal effects.

No validated DRS3 zebrafish, Drosophila, C. elegans, rat, patient-iPSC, cranial-motor-neuron organoid, or disease-specific cell-line model was identified in the retrieved evidence. Suitable future applications include lineage-restricted Mafb deletion, human iPSC-derived hindbrain motor neurons and otic organoids, single-cell transcriptomics of affected embryonic lineages, and rescue testing of variant-specific transcriptional activity.

Recent developments and expert interpretation

The most relevant recent synthesis is Fujino, Ojima, and Takahashi, published September 27, 2023 in Genes (14:1883; DOI/URL: https://doi.org/10.3390/genes14101883). It places DRS within the spectrum of domain- and mechanism-specific large-MAF disorders, highlights the p.Leu239Pro DNA-binding defect, and concludes that MAFB mutations compromise abducens neurons, inner ear, and—in broader phenotypes—podocytes. (fujino2023exploringlargemafa pages 7-9, fujino2023exploringlargemaf pages 7-9)

A July 20, 2023 genetics review emphasizes the contemporary framework that CCDDs result from improper cranial motor-neuron differentiation or abnormal axon guidance and that these remain the strabismus forms with established Mendelian causal genes. DOI/URL: https://doi.org/10.3389/fopht.2023.1233866. (sanchez2023geneticsofstrabismus pages 1-2, sanchez2023geneticsofstrabismus pages 4-5)

No 2023–2024 primary study was found that materially expanded the number of molecularly confirmed MAFB-DRS3 families, established population prevalence, or introduced a targeted therapy. Thus, the 2016 human/mouse study remains the disease-defining primary source, while 2023 work mainly consolidates mechanistic understanding.

Evidence-quality assessment and knowledge gaps

Strong evidence: MAFB causality; monoallelic autosomal inheritance; congenital CCDD classification; abducens/extraocular-innervation mechanism; variable inner-ear/hearing involvement; mouse recapitulation.

Moderate or extrapolated evidence: diagnostic work-up, natural history, ophthalmic surgery, quality-of-life burden, and general DRS epidemiology. These derive largely from DRS overall rather than genetically confirmed DRS3.

Currently unavailable: molecular-case prevalence and incidence; exact penetrance; robust phenotype percentages; DRS3-specific sex/ethnic/geographic distribution; complete contemporary variant table with gnomAD frequencies; validated modifiers; disease-specific transcriptomic/proteomic/metabolomic signatures; standardized diagnostic criteria; survival statistics; treatment-response rates; and disease-modifying clinical trials.

For knowledge-base implementation, each general-DRS datum should therefore carry an evidence qualifier such as “phenotypic-parent evidence; not MAFB-specific.” Variant assertions should be transcript-versioned and rechecked directly in ClinVar/gnomAD before ingestion.

References

(NCT03059420 chunk 1): Elizabeth Engle. Genetic Studies of Strabismus, Congenital Cranial Dysinnervation Disorders (CCDDs), and Their Associated Anomalies. Boston Children's Hospital. 2004. ClinicalTrials.gov Identifier: NCT03059420
(OpenTargets Search: Duane retraction syndrome 3-MAFB): Open Targets Query (Duane retraction syndrome 3-MAFB, 1 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.
(fujino2023exploringlargemaf pages 7-9): Mitsunori Fujino, Masami Ojima, and Satoru Takahashi. Exploring large maf transcription factors: functions, pathology, and mouse models with point mutations. Genes, 14:1883, Sep 2023. URL: https://doi.org/10.3390/genes14101883, doi:10.3390/genes14101883. This article has 15 citations.
(sanchez2023geneticsofstrabismus pages 1-2): Mayra Martinez Sanchez and Mary C. Whitman. Genetics of strabismus. Frontiers in Ophthalmology, Jul 2023. URL: https://doi.org/10.3389/fopht.2023.1233866, doi:10.3389/fopht.2023.1233866. This article has 34 citations.
(derespinis1993duanesretractionsyndrome. pages 15-17): Patrick A. DeRespinis, Anthony R. Caputo, Rudolph S. Wagner, and Suqin Guo. Duane's retraction syndrome. Survey of ophthalmology, 38 3:257-88, Nov 1993. URL: https://doi.org/10.1016/0039-6257(93)90077-k, doi:10.1016/0039-6257(93)90077-k. This article has 325 citations and is from a peer-reviewed journal.
(derespinis1993duanesretractionsyndrome. pages 10-11): Patrick A. DeRespinis, Anthony R. Caputo, Rudolph S. Wagner, and Suqin Guo. Duane's retraction syndrome. Survey of ophthalmology, 38 3:257-88, Nov 1993. URL: https://doi.org/10.1016/0039-6257(93)90077-k, doi:10.1016/0039-6257(93)90077-k. This article has 325 citations and is from a peer-reviewed journal.
(murillocorrea2009clinicalfeaturesassociated pages 1-2): Claudia E. Murillo-Correa, Veronica Kon-Jara, Elizabeth C. Engle, and Juan C. Zenteno. Clinical features associated with an i126m alpha2-chimaerin mutation in a family with autosomal-dominant duane retraction syndrome. Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus, 13 3:245-8, Jun 2009. URL: https://doi.org/10.1016/j.jaapos.2009.03.007, doi:10.1016/j.jaapos.2009.03.007. This article has 23 citations.
(fujino2023exploringlargemafa pages 7-9): M Fujino, M Ojima, and S Takahashi. Exploring large maf transcription factors: functions, pathology, and mouse models with point mutations. genes 2023, 14, 1883. Unknown journal, 2023.
(derespinis1993duanesretractionsyndrome. pages 27-28): Patrick A. DeRespinis, Anthony R. Caputo, Rudolph S. Wagner, and Suqin Guo. Duane's retraction syndrome. Survey of ophthalmology, 38 3:257-88, Nov 1993. URL: https://doi.org/10.1016/0039-6257(93)90077-k, doi:10.1016/0039-6257(93)90077-k. This article has 325 citations and is from a peer-reviewed journal.
(derespinis1993duanesretractionsyndrome. pages 26-27): Patrick A. DeRespinis, Anthony R. Caputo, Rudolph S. Wagner, and Suqin Guo. Duane's retraction syndrome. Survey of ophthalmology, 38 3:257-88, Nov 1993. URL: https://doi.org/10.1016/0039-6257(93)90077-k, doi:10.1016/0039-6257(93)90077-k. This article has 325 citations and is from a peer-reviewed journal.
(NCT03059420 chunk 2): Elizabeth Engle. Genetic Studies of Strabismus, Congenital Cranial Dysinnervation Disorders (CCDDs), and Their Associated Anomalies. Boston Children's Hospital. 2004. ClinicalTrials.gov Identifier: NCT03059420
(sanchez2023geneticsofstrabismus pages 4-5): Mayra Martinez Sanchez and Mary C. Whitman. Genetics of strabismus. Frontiers in Ophthalmology, Jul 2023. URL: https://doi.org/10.3389/fopht.2023.1233866, doi:10.3389/fopht.2023.1233866. This article has 34 citations.

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1. Disease Information

2. Etiology

3. Phenotypes

4. Genetic/Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

10. Diagnostics

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Duane Retraction Syndrome 3 With or Without Deafness

Executive summary and evidence boundaries

1. Disease information

Definition

Identifiers and synonyms

2. Etiology and risk/protective factors

Causal factor

Risk factors

Protective factors and gene–environment interaction

3. Phenotypes

Core and associated manifestations

Frequency and severity

Quality of life

4. Genetic and molecular information

Gene and protein

Pathogenic variants

Functional consequence

5. Environmental information

6. Mechanism and pathophysiology

Causal chain

Relevant processes, cells, and structures

7. Anatomical structures affected

Primary

Secondary/variable

Lateralization

8. Temporal development

9. Inheritance and population

Inheritance

Epidemiology

10. Diagnostics

Clinical diagnosis

Imaging and electrophysiology

Genetic testing strategy

Differential diagnosis

Screening

11. Outcome and prognosis

12. Treatment and current applications

Ophthalmic care

Hearing management

Trials and recent implementation