Keratoderma Hereditarium Mutilans

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Subtypes

2

Classic Vohwinkel Syndrome

The classic form caused by GJB2 mutations, featuring the complete triad of palmoplantar keratoderma, pseudoainhum, and sensorineural hearing loss.

Show evidence (1 reference)

PMID:10369869 SUPPORT

"VS is characterized by papular and honeycomb keratoderma associated with constrictions of digits leading to autoamputation, distinctive starfish-like acral keratoses and moderate degrees of deafness. "

This landmark paper identified the D66H mutation in GJB2 as causative for classic Vohwinkel syndrome with the characteristic triad.

Loricrin Keratoderma (Variant Vohwinkel Syndrome)

A variant form caused by LOR gene mutations, featuring keratoderma and pseudoainhum but with ichthyosis instead of hearing loss. Also known as Camisa variant.

Show evidence (2 references)

PMID:9326398 SUPPORT

"Vohwinkel's keratoderma is thus clinically and genetically heterogeneous. Only the variant with ichthyosis appears to be due to loricrin mutation. "

This paper established that loricrin mutations cause the ichthyotic variant without hearing loss.

PMID:12072018 SUPPORT

"Functional studies in transgenic mice have shown that the accumulation of mutant loricrin in the nucleus appears to interfere with the later stages of epidermal differentiation, thereby explaining the clinical manifestations of ichthyosis, keratoderma and pseudoainhum. "

Confirms loricrin mutations underlie the ichthyotic variant of Vohwinkel syndrome.

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References

4

DOI:10.1016/j.yadr.2007.07.011

Ichthyosis Update: Towards a Function-Driven Model of Pathogenesis of the Disorders of Cornification and the Role of Corneocyte Proteins in These Disorders

No top-level findings curated for this source.

DOI:10.1093/hmg/8.7.1237

A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families

No top-level findings curated for this source.

DOI:10.1177/2050313x231204197

Palmoplantar keratoderma, pseudo-ainhum and knuckle pads in an African patient: A case report

No top-level findings curated for this source.

DOI:10.3390/biology10010059

Connexins and the Epithelial Tissue Barrier: A Focus on Connexin 26

No top-level findings curated for this source.

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Pathophysiology

5

Gap Junction Dysfunction

Mutations in GJB2 disrupt connexin 26 function, impairing gap junction-mediated intercellular communication in the epidermis and cochlea. The D66H mutation occurs at a highly conserved residue in the first extracellular domain and may interfere with connexon assembly, docking, or gating properties. This leads to defective ion homeostasis and impaired cellular coordination during differentiation.

Keratinocyte link

Gap junction assembly link Cell-cell signaling link

Skin of palm and sole link

Show evidence (2 references)

PMID:10369869 SUPPORT

"This mutation occurs at a highly conserved residue in the first extracellular domain of the Cx26 molecule, and may exert its effects by interfering with assembly into connexons, docking with adjacent cells or gating properties of the gap junction. "

Describes the molecular mechanism of GJB2 D66H mutation disrupting gap junction function.

PMID:14681042 SUPPORT Model Organism

"Expression of the transgene resulted in a loss of Cx26 and Cx30 at intercellular junctions of epidermal keratinocytes and accumulation of these connexins in the cytoplasm. "

Transgenic mouse model demonstrates that D66H mutation causes loss of connexins at cell junctions.

Abnormal Epidermal Differentiation

Defective gap junction signaling leads to hyperproliferation and abnormal keratinization of palmoplantar epidermis, resulting in the characteristic thickened honeycomb-patterned skin. The mutation impairs epidermal differentiation as well as inner ear function.

Keratinocyte link

Keratinocyte differentiation link

Show evidence (2 references)

PMID:10369869 SUPPORT

"Our results provide evidence that a specific mutation in Cx26 can impair epidermal differentiation, as well as inner ear function. "

Establishes that GJB2 mutations affect both epidermal and cochlear function.

PMID:14681042 SUPPORT Model Organism

"Following birth, the transgenic mice developed keratoderma similar to that of human carriers of Cx26 (D66H). "

Transgenic mice expressing mutant Cx26 develop keratoderma like human patients.

Mutant Loricrin Nuclear Accumulation

In the ichthyotic variant, mutant loricrin is mislocalized to the nuclei of granular layer keratinocytes and fails to incorporate into the cornified cell envelope. The frameshift mutation creates an abnormal C-terminal peptide containing nuclear localization signals, causing aberrant nuclear translocation and interference with late stages of epidermal differentiation.

Keratinocyte link

Cornified envelope assembly link Keratinocyte differentiation link

Show evidence (3 references)

PMID:11121146 SUPPORT

"Mutant loricrin, as a dominant negative disrupter, is not likely to affect cornified cell envelope crosslinking directly, but seems to interfere with nuclear/nucleolar functions of differentiating keratinocytes. "

Describes the mechanism by which mutant loricrin causes disease through nuclear interference.

PMID:9326398 SUPPORT

"a G insertion producing a frameshift after codon 231 and an abnormal C-terminal peptide lacking residues necessary for cross-linking. "

Identifies the specific mutation and its effect on loricrin protein structure.

PMID:11038186 SUPPORT Model Organism

"Immunofluorescence and immunoelectron microscopy showed the mutant loricrin protein in the nucleus and cytoplasm of epidermal keratinocytes, but did not detect the protein in the cornified cell envelope. "

Transgenic mouse studies confirm nuclear mislocalization of mutant loricrin.

Digital Constriction and Autoamputation

Fibrous bands encircle digits (pseudoainhum), progressively constricting and potentially leading to spontaneous amputation. The pathogenesis involves aberrant keratinization and tissue remodeling secondary to keratinocyte dysfunction.

Show evidence (1 reference)

PMID:10369869 SUPPORT

"VS is characterized by papular and honeycomb keratoderma associated with constrictions of digits leading to autoamputation "

Describes the progression from constricting bands to autoamputation.

Cochlear Dysfunction

Connexin 26 is essential for potassium recycling in the cochlea. Its dysfunction disrupts the endocochlear potential required for auditory transduction, causing sensorineural hearing loss. This phenotype is specific to GJB2 mutations and is absent in the loricrin-associated variant.

Cochlea link

Show evidence (2 references)

PMID:10369869 SUPPORT

"Mutations in the connexin26 (Cx26) gene (GJB2) at 13q11-q13 are a major cause of autosomal recessive hearing loss (DFNB1), but have also been reported in autosomal dominant deafness (DFNA3). "

Establishes the role of GJB2 in both skin and hearing phenotypes.

PMID:9326398 SUPPORT

"In our second family (VK2), affected members had sensorineural deafness but not ichthyosis. "

Confirms that deafness segregates with connexin mutations, not loricrin mutations.

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Pathograph

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Phenotypes

8

Ear 1

Sensorineural Hearing Loss FREQUENT Sensorineural hearing impairment (HP:0000407)

Show evidence (2 references)

PMID:10369869 SUPPORT

"A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families. "

Sensorineural deafness is part of the classic Vohwinkel phenotype.

PMID:20031451 SUPPORT

"Vohwinkel Syndrome (VS) is a type of diffuse hereditary palmoplantar keratodermas (DHPPK) accompanied by skeletal dimorphisms and sensorineural deafness. "

Confirms sensorineural deafness as a component of the syndrome.

Integument 6

Palmoplantar Keratoderma VERY_FREQUENT Palmoplantar keratoderma (HP:0000982)

Show evidence (1 reference)

PMID:10369869 SUPPORT

"VS is characterized by papular and honeycomb keratoderma associated with constrictions of digits leading to autoamputation "

Honeycomb keratoderma is a defining feature of the syndrome.

Honeycomb Palmoplantar Hyperkeratosis VERY_FREQUENT Honeycomb palmoplantar hyperkeratosis (HP:0007465)

Show evidence (1 reference)

PMID:10369869 SUPPORT

"VS is characterized by papular and honeycomb keratoderma "

Honeycomb pattern is characteristic of the syndrome.

Starfish-Shaped Hyperkeratoses FREQUENT Hyperkeratosis (HP:0000962)

Show evidence (1 reference)

PMID:10369869 SUPPORT

"distinctive starfish-like acral keratoses "

Starfish-like acral keratoses are a characteristic feature.

Knuckle Pads FREQUENT Knuckle pad (HP:0032541)

Show evidence (2 references)

PMID:6237617 SUPPORT

"keratotic structures taking the shape of a starfish and/or knuckle pads on the dorsal surfaces of the hands "

Describes starfish-shaped keratoses and knuckle pads as characteristic features.

PMID:30335335 SUPPORT

"The classic Vohwinkel syndrome is a hereditary PPK associated with "starfish" keratoses on the knuckles "

StatPearls review confirms starfish keratoses on knuckles are part of classic syndrome.

Ichthyosis VERY_FREQUENT Ichthyosis (HP:0008064)

Show evidence (2 references)

PMID:9326398 SUPPORT

"Our first family (VK1) also had ichthyosis but not deafness. "

Ichthyosis is present in the loricrin variant but not classic form.

PMID:11038186 SUPPORT Model Organism

"At birth, transgenic mice (ML.VS) exhibited erythrokeratoderma with an epidermal barrier dysfunction. 4 d after birth, high-expressing transgenic animals showed a generalized scaling of the skin "

Transgenic mice with mutant loricrin develop ichthyosis-like scaling.

Alopecia OCCASIONAL Alopecia (HP:0001596)

Limbs 1

Pseudoainhum VERY_FREQUENT Autoamputation of digits (HP:0007460)

Show evidence (2 references)

PMID:10369869 SUPPORT

"constrictions of digits leading to autoamputation "

Pseudoainhum with potential autoamputation is a key feature.

PMID:12072018 SUPPORT

"the clinical manifestations of ichthyosis, keratoderma and pseudoainhum "

Pseudoainhum is a feature of both genetic forms.

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Genetic Associations

2

GJB2 (Causative)

Show evidence (2 references)

PMID:10369869 SUPPORT

"All 10 affected members were heterozygous for a non-conservative mutation, D66H, in Cx26. The same mutation was found subsequently in affected individuals from two unrelated Spanish and Italian pedigrees segregating VS, suggesting that D66H in Cx26 is a common mutation in classical VS. "

Identifies D66H as a common mutation in classic Vohwinkel syndrome across multiple families.

PMID:20031451 SUPPORT

"Genetic study showed a nucleotide change (c.196G>C) in exon 1 of GJB2 gene, producing a missense mutation, D66H. "

Confirms the specific nucleotide change causing the D66H mutation.

LOR (Causative)

Show evidence (2 references)

PMID:9326398 SUPPORT

"a G insertion producing a frameshift after codon 231 and an abnormal C-terminal peptide lacking residues necessary for cross-linking. "

Identifies the specific loricrin mutation causing the ichthyotic variant.

PMID:12072018 SUPPORT

"identified a recurrent insertion mutation in the loricrin gene resulting in a mutant polypeptide with an unusual C terminus. "

Confirms the recurrent nature of loricrin insertion mutations.

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Treatments

5

Keratolytic Therapy

Topical agents containing salicylic acid or urea to soften and reduce hyperkeratotic skin lesions on palms and soles.

Emollients

Regular application of moisturizers to maintain skin hydration and reduce cracking and discomfort.

Retinoids

Oral retinoids (isotretinoin, acitretin) may help control hyperkeratosis and can prevent digital constrictions in some patients. Relapse typically occurs upon discontinuation of treatment.

Show evidence (1 reference)

PMID:6237617 SUPPORT

"One of the patients was successfully treated with isotretinoin, 0.6 mg/kg/day orally. "

First report of successful isotretinoin treatment for the ichthyotic variant of Vohwinkel syndrome.

Surgical Intervention

Surgical release of constricting bands may be necessary to prevent autoamputation of digits; in severe cases, amputation may be required.

Hearing Aids and Cochlear Implants

Audiological management for sensorineural hearing loss, including hearing aids for mild-moderate loss and cochlear implants for profound loss. Applicable only to classic GJB2-associated form.

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Literature Summaries

2

Disorder ▸

Disorder

Name: Keratoderma Hereditarium Mutilans
Category: Mendelian
Existing deep-research providers: falcon
Existing evidence reference count in YAML: 37

Key Pathophysiology Nodes

Gap Junction Dysfunction
Abnormal Epidermal Differentiation
Mutant Loricrin Nuclear Accumulation
Digital Constriction and Autoamputation
Cochlear Dysfunction
Deep research literature mapping

Citation Inventory (for evidence mapping)

DOI:10.1016/j.yadr.2007.07.011
DOI:10.1093/hmg/8.7.1237
DOI:10.1177/2050313x231204197
DOI:10.3390/biology10010059
DOI:10.4103/idoj.idoj_367_18

Falcon ▸

Disease Pathophysiology Research Report

Edison Scientific Literature 17 citations 2026-02-04T17:32:10.918652

Disease Pathophysiology Research Report

Target Disease - Disease Name: Keratoderma Hereditarium Mutilans (Keratoderma hereditaria mutilans; Vohwinkel syndrome; loricrin keratoderma/Camisa variant) - MONDO ID: Not confidently identified here (leave blank pending authoritative mapping) - Category: Mendelian (autosomal dominant) (maestrini1999amissensemutation pages 1-2, sethuraman2019hereditarypalmoplantarkeratoderma pages 4-5)

Pathophysiology description Vohwinkel syndrome (VS) is a mutilating diffuse transgrediens palmoplantar keratoderma that progresses to constricting bands (pseudo-ainhum) and may culminate in auto-amputation of digits. The classic form is caused by dominant missense mutations in GJB2 encoding connexin 26 (Cx26), which disrupt epidermal gap-junctional communication and can confer aberrant hemichannel properties, leading to impaired intercellular signaling, altered epidermal calcium gradients, disordered keratinocyte differentiation, and barrier dysfunction. Sensorineural deafness commonly co-segregates in the classic GJB2-associated form due to inner-ear gap junction involvement (Human Molecular Genetics, Jul 1999; DOI:10.1093/hmg/8.7.1237) (maestrini1999amissensemutation pages 1-2, garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6, govender2023palmoplantarkeratodermapseudoainhum pages 2-4). The ichthyotic (Camisa) variant is genetically distinct and results from LOR mutations; mutant loricrin mislocalizes to keratinocyte nuclei and fails to incorporate into the cornified envelope, producing defective cornification, parakeratosis, barrier impairment, and ichthyosiform changes in addition to palmoplantar keratoderma (Advances in Dermatology, Jan 2007; DOI:10.1016/j.yadr.2007.07.011) (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15).

Key concepts and definitions - Gap junctions and hemichannels: Connexins oligomerize into hexameric connexons (hemichannels) that dock to form gap junction channels permitting passage of ions and small metabolites (<1 kDa) for intercellular coordination in the epidermis and cochlea (Biology, Jan 2021; DOI:10.3390/biology10010059) (garciavega2021connexinsandthe pages 4-6). In VS, Cx26 mutations in extracellular loop 1 (e.g., D66H) impair connexon assembly/docking or gating and can yield abnormal hemichannel activity (maestrini1999amissensemutation pages 1-2, garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6). As one review summarizes, mutant Cx26 can form “nonfunctional gap junctions but hyperactive hemichannels,” perturbing calcium gradients and barrier function (Biology, 2021; https://doi.org/10.3390/biology10010059) (garciavega2021connexinsandthe pages 13-14). - Cornified envelope and loricrin: Loricrin is a major structural protein of the cornified envelope. In the Camisa variant, “mutant loricrin is mislocalized to nuclei of the granular layer, fails to incorporate into the cornified envelope and is retained in parakeratotic stratum corneum,” resulting in hyperkeratosis, parakeratosis, and increased transepidermal water loss (Advances in Dermatology, 2007; https://doi.org/10.1016/j.yadr.2007.07.011) (schmuth2007ichthyosisupdatetowards pages 5-6).

Recent developments and latest research (prioritize 2023–2024) - Case-based mechanistic reinforcement (2023): An African patient with transgrediens PPK, pseudo-ainhum, and knuckle pads illustrated the clinical trajectory toward amputation; the discussion emphasizes connexin biology (connexon hexamers, multi-connexin skin expression) and postulated mechanisms including loss or abnormal gap junction function, trafficking defects, and dominant-negative effects; disruption of the epidermal calcium gradient is highlighted as a mechanism affecting differentiation (SAGE Open Medical Case Reports, Jan 2023; DOI:10.1177/2050313x231204197) (govender2023palmoplantarkeratodermapseudoainhum pages 2-4). - Contemporary connexin 26 mechanism reviews (context to VS, 2021–2022): Reviews detail Cx26 trafficking, oligomerization, and mutation classes, linking VS mutations to extracellular loop 1 and non-inflammatory keratoderma phenotypes; they also discuss hyperactive hemichannel states and potential pharmacologic blockade (Biology, 2021; DOI:10.3390/biology10010059) (garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6). While slightly older, these sources remain mechanistically relevant and are consistent with classic VS data (maestrini1999amissensemutation pages 1-2).

Current applications and real-world implementations - Surgical management for pseudo-ainhum: Progressive constriction bands necessitate timely surgical intervention; amputation may be required in advanced cases, as illustrated in the 2023 report (SAGE Open Medical Case Reports, 2023; https://doi.org/10.1177/2050313x231204197) (govender2023palmoplantarkeratodermapseudoainhum pages 2-4). - Medical management: Keratolytics, emollients, and systemic retinoids have been used; isotretinoin has been reported in a Vohwinkel variant (advocated historically), though controlled data are limited (Advances in Dermatology, 2007; DOI:10.1016/j.yadr.2007.07.011) (schmuth2007ichthyosisupdatetowards pages 14-15). Connexin-targeted modulators are discussed in preclinical contexts (hemichannel blockers), but clinical translation specific to VS remains investigational (Biology, 2021; DOI:10.3390/biology10010059) (garciavega2021connexinsandthe pages 13-14).

Expert opinions and analysis from authoritative sources - Landmark genetic causation: The identification of GJB2 D66H as causative in classical VS across three unrelated families provided firm genetic and mechanistic grounding for the gap-junction hypothesis and explained the associated deafness via cochlear gap junction disruption (Human Molecular Genetics, 1999; https://doi.org/10.1093/hmg/8.7.1237) (maestrini1999amissensemutation pages 1-2). The authors infer that VS keratoderma can reflect an abnormal healing/differentiation response arising from defective connexin-mediated growth regulation in keratinocytes (maestrini1999amissensemutation pages 6-6). - Function-driven cornification model: Expert reviews of disorders of cornification position loricrin keratoderma (Camisa variant) as a prototypic cornified envelope substrate defect with downstream barrier failure, parakeratosis, and compensatory responses, mechanistically distinct from connexin channelopathies (Advances in Dermatology, 2007; https://doi.org/10.1016/j.yadr.2007.07.011) (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15).

Relevant statistics and data from recent studies - Clinical course markers: The 2023 case report documents prior constriction bands progressing to auto-amputations and current surgical amputation, reflecting the mutilating natural history when constriction bands are untreated or refractory (SAGE Open Medical Case Reports, 2023; https://doi.org/10.1177/2050313x231204197) (govender2023palmoplantarkeratodermapseudoainhum pages 2-4). While formal prevalence statistics are scarce due to extreme rarity, the genetic series demonstrating three unrelated families with GJB2 D66H remains a seminal data point underpinning causality (Human Molecular Genetics, 1999) (maestrini1999amissensemutation pages 1-2).

1) Core Pathophysiology - Primary mechanisms - GJB2/Cx26 (classic VS): Dominant missense variants disrupt gap junction intercellular communication in the epidermis and inner ear and can create hyperactive hemichannel states. Consequences include impaired keratinocyte coordination, altered calcium gradients, dysregulated differentiation, and barrier dysfunction; deafness results from cochlear gap junction defects (maestrini1999amissensemutation pages 1-2, garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6, govender2023palmoplantarkeratodermapseudoainhum pages 2-4). - LOR (Camisa variant): Mutant loricrin shows nuclear mislocalization, deficient incorporation into the cornified envelope, and defective cornification with parakeratosis, driving ichthyosis and palmoplantar hyperkeratosis (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15). - Dysregulated molecular pathways - Cell–cell communication via gap junctions/hemichannels; calcium signaling critical for keratinocyte differentiation (garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6, govender2023palmoplantarkeratodermapseudoainhum pages 2-4). - Cornified envelope assembly and keratinocyte terminal differentiation pathways (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15). - Affected cellular processes - Connexin biosynthesis/trafficking, connexon assembly/docking, hemichannel gating; keratinocyte differentiation and desquamation; barrier formation and water homeostasis (garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6, schmuth2007ichthyosisupdatetowards pages 5-6).

2) Key Molecular Players - Genes/Proteins (HGNC): - GJB2 (Connexin 26/Cx26) — causal in classical VS (maestrini1999amissensemutation pages 1-2). - LOR (Loricrin) — causal in ichthyotic/Camisa variant (schmuth2007ichthyosisupdatetowards pages 14-15, schmuth2007ichthyosisupdatetowards pages 5-6). - Chemical Entities (CHEBI; examples contextual): Calcium ions (Ca2+) as a key differentiation cue; ATP/IP3 as hemichannel-permeant signaling molecules implicated in connexin gain-of-function states (mechanistic reviews) (garciavega2021connexinsandthe pages 13-14). - Cell Types (CL): Keratinocytes (CL:0000312) as primary cells; epidermal resident immune cells may respond secondarily to barrier failure (garciavega2021connexinsandthe pages 13-14, schmuth2007ichthyosisupdatetowards pages 5-6). - Anatomical Locations (UBERON): Palmoplantar skin — skin of palm (UBERON:0002427), skin of sole (UBERON:0002428), epidermis (UBERON:0001003) (sethuraman2019hereditarypalmoplantarkeratoderma pages 4-5, maestrini1999amissensemutation pages 1-2).

3) Biological Processes (for GO annotation) - Gap junction-mediated intercellular communication (GO:0007154), cell–cell signaling (GO:0007267), ion transport including calcium handling (GO:0006816) — disrupted in GJB2-associated VS (garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6). - Keratinocyte differentiation (GO:0030216) and cornified envelope formation/cornification (e.g., GO:0070268) — disrupted in LOR-associated Camisa variant (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15). - Barrier function and desquamation processes inferred from parakeratosis and TEWL increases in LOR disease (schmuth2007ichthyosisupdatetowards pages 5-6).

4) Cellular Components - Gap junction plaques at the plasma membrane; connexin hemichannels at the plasma membrane/extracellular interface (garciavega2021connexinsandthe pages 4-6). - Cornified envelope at the corneocyte periphery; nuclear mislocalization of mutant loricrin within granular layer keratinocytes (schmuth2007ichthyosisupdatetowards pages 5-6).

5) Disease Progression - Sequence of events - Classic VS (GJB2): Early-life diffuse/transgrediens palmoplantar hyperkeratosis and acral keratoses/knuckle pads, progressing to circumferential constriction bands (pseudo-ainhum) that can cause auto-amputation if untreated; many patients have concomitant sensorineural deafness (maestrini1999amissensemutation pages 1-2, govender2023palmoplantarkeratodermapseudoainhum pages 2-4). - Camisa variant (LOR): Similar palmoplantar keratoderma with prominent ichthyosis and parakeratosis due to defective cornified envelope, with risk of constricting bands and mutilation (schmuth2007ichthyosisupdatetowards pages 14-15, schmuth2007ichthyosisupdatetowards pages 5-6).

6) Phenotypic Manifestations - Key clinical phenotypes and mechanistic links - Diffuse/transgrediens palmoplantar keratoderma (HP:0000982) — hyperproliferation/hyperkeratosis from disturbed differentiation (GJB2/LOR) (maestrini1999amissensemutation pages 1-2, schmuth2007ichthyosisupdatetowards pages 14-15). - Pseudo-ainhum/constriction bands (HP:0001052) with progression to auto-amputation — chronic mechanical/keratinization dysregulation driving fibrous bands around digits (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, maestrini1999amissensemutation pages 1-2). - Knuckle pads and starfish-like keratoses — focal acral hyperkeratoses related to altered keratinocyte homeostasis (maestrini1999amissensemutation pages 1-2, govender2023palmoplantarkeratodermapseudoainhum pages 2-4). - Sensorineural deafness (HP:0000407) in classic GJB2 VS — cochlear gap junction dysfunction (maestrini1999amissensemutation pages 1-2). - Ichthyosis/parakeratosis in Camisa variant — defective cornified envelope assembly due to mutant loricrin (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15).

Gene/protein annotations with ontology terms - GJB2 (HGNC:4286) — Connexin 26; Processes: GO:0007154, GO:0007267, GO:0006816; Components: plasma membrane, gap junction; Phenotypes: HP:0000982, HP:0001052, HP:0200041, HP:0000407; Cells: CL:0000312; Anatomy: UBERON:0002427/0002428/0001003 (maestrini1999amissensemutation pages 1-2, garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6, govender2023palmoplantarkeratodermapseudoainhum pages 2-4). - LOR (HGNC:6667) — Loricrin; Processes: GO:0030216, GO:0070268; Components: cornified envelope; Phenotypes: HP:0000982, HP:0001052; Cells: CL:0000312; Anatomy: UBERON:0002427/0002428/0001003 (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15).

Cell type involvement (CL terms) - Keratinocyte (CL:0000312) — site of connexin expression/communication and loricrin cornified envelope assembly; aberrant signaling/cornification underlies VS phenotypes (garciavega2021connexinsandthe pages 13-14, schmuth2007ichthyosisupdatetowards pages 5-6).

Anatomical locations (UBERON terms) - Skin of palm (UBERON:0002427); skin of sole (UBERON:0002428); epidermis (UBERON:0001003) as the primary anatomical sites, consistent with palmoplantar specificity (sethuraman2019hereditarypalmoplantarkeratoderma pages 4-5, maestrini1999amissensemutation pages 1-2).

Chemical entities (CHEBI; examples) - Calcium ion (CHEBI:29108) — epidermal calcium gradient essential for differentiation; perturbed by connexin dysfunction (review context) (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, garciavega2021connexinsandthe pages 13-14). - ATP (CHEBI:15422) and IP3 (CHEBI:16595) — candidate hemichannel-permeant signals in connexin gain-of-function states discussed in reviews (garciavega2021connexinsandthe pages 13-14).

Evidence items with PMIDs/URLs/dates (representative) - Maestrini et al., Human Molecular Genetics, 1999-07; “A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel’s syndrome) …” DOI:10.1093/hmg/8.7.1237; URL: https://doi.org/10.1093/hmg/8.7.1237 (maestrini1999amissensemutation pages 1-2). - Schmuth et al., Advances in Dermatology, 2007-01; “Mutant loricrin is mislocalized to nuclei … fails to incorporate into the cornified envelope …” DOI:10.1016/j.yadr.2007.07.011; URL: https://doi.org/10.1016/j.yadr.2007.07.011 (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15). - Garcia-Vega et al., Biology, 2021-01; connexin 26 in epithelial barrier, gap junction vs hemichannel dysfunction, potential pharmacology. DOI:10.3390/biology10010059; URL: https://doi.org/10.3390/biology10010059 (garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6). - Govender & Pillay, SAGE Open Medical Case Reports, 2023-01; palmoplantar keratoderma with pseudo-ainhum/knuckle pads, surgical amputation; connexin mechanisms overview. DOI:10.1177/2050313x231204197; URL: https://doi.org/10.1177/2050313x231204197 (govender2023palmoplantarkeratodermapseudoainhum pages 2-4).

Direct quotes (supporting key statements) - “A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel’s syndrome)” (Human Molecular Genetics, 1999) (maestrini1999amissensemutation pages 1-2). - “Mutant loricrin is mislocalized to nuclei of the granular layer, fails to incorporate into the cornified envelope and is retained in parakeratotic stratum corneum” (Advances in Dermatology, 2007) (schmuth2007ichthyosisupdatetowards pages 5-6). - “Gap junctions are intercellular channels… each connexon is composed of six connexin sub-units” and mutant connexins may “disrupt the epidermal calcium gradient affecting keratinocyte differentiation” (SAGE Open Medical Case Reports, 2023) (govender2023palmoplantarkeratodermapseudoainhum pages 2-4).

Embedded summary artifact | Gene (HGNC) | Protein | Variant examples | Primary mechanism | Dysregulated pathways/processes (GO IDs/names) | Principal cell types (CL IDs) | Anatomical sites (UBERON IDs) | Key phenotypes (HPO IDs) | Representative sources | |---|---|---|---|---|---|---|---|---| | GJB2 | Connexin 26 (Cx26) | D66H (classic VS), other missense (e.g., p.Tyr65His) | Dominant missense → impaired gap‑junction assembly/function ± gain‑of‑function hemichannels → disrupted intercellular communication, altered Ca2+ gradient and keratinocyte differentiation | GO:0007154 (cell communication); GO:0007267 (cell–cell signaling); GO:0006816 (ion transport/calcium handling) | Keratinocyte (CL:0000312) | Skin of palm (UBERON:0002427), skin of sole (UBERON:0002428), epidermis (UBERON:0001003) | Palmoplantar keratoderma; pseudo‑ainhum/ constriction bands; knuckle pads; sensorineural hearing impairment (HP:0000982; HP:0001052; HP:0200041; HP:0000407) | (maestrini1999amissensemutation pages 6-6, maestrini1999amissensemutation pages 1-2, garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6, govender2023palmoplantarkeratodermapseudoainhum pages 2-4) | | LOR | Loricrin | Recurrent insertion/frameshift mutations observed in Camisa (ichthyotic) variant (reported recurrent LOR mutations) | Mutant loricrin mislocalized (nuclear accumulation), fails to incorporate into cornified envelope → defective cornified envelope assembly, abnormal cornification/desquamation, barrier dysfunction and hyperkeratosis/ichthyosis | GO:0030216 (keratinocyte differentiation); GO:0070268 (cornified envelope formation / cornification) | Keratinocyte (CL:0000312) | Skin of palm (UBERON:0002427), skin of sole (UBERON:0002428), epidermis (UBERON:0001003) | Diffuse/transgrediens palmoplantar hyperkeratosis; ichthyosis variant; pseudo‑ainhum; risk of mutilation (HP:0000982; HP:0001052) | (schmuth2007ichthyosisupdatetowards pages 5-6, schmuth2007ichthyosisupdatetowards pages 14-15, sethuraman2019hereditarypalmoplantarkeratoderma pages 4-5) | | Connexin/hemichannel (general) | Connexin hemichannels / gap junctions (GJB family) | Disease‑associated alleles across GJB family (e.g., S17F, F142L among others) | Gain‑of‑function hemichannels → leaky ATP/Ca2+/IP3 release, inflammation; loss or dominant‑negative loss of gap‑junctional coupling → impaired tissue coordination, altered proliferation/differentiation | GO:0007154 (cell communication); GO:0006816 (ion transport); GO:0006954 (inflammatory response) | Keratinocyte (CL:0000312); epidermal resident immune cells (various CL IDs) | Epidermis and epidermal appendages; palmoplantar skin (UBERON:0001003, UBERON:0002427, UBERON:0002428) | Palmoplantar hyperkeratosis, inflammation, susceptibility to secondary infection/complications; hearing loss in syndromic forms (HP:0000982; HP:0000407) | (garciavega2021connexinsandthe pages 13-14, garciavega2021connexinsandthe pages 4-6, govender2023palmoplantarkeratodermapseudoainhum pages 2-4, sethuraman2019hereditarypalmoplantarkeratoderma pages 4-5) |

Table: Compact summary of key genes/proteins, variant examples, primary mechanisms, relevant GO/CL/UBERON/HPO ontology mappings, and representative evidence IDs for Keratoderma Hereditarium Mutilans (Vohwinkel syndrome). This table supports rapid integration into a disease knowledge base and links claims to source context IDs.

Notes and gaps - MONDO ID should be confirmed in a dedicated ontology resource before entry finalization. Emerging therapeutic concepts targeting connexin hemichannels are promising but remain preclinical or exploratory in VS.

References

(maestrini1999amissensemutation pages 1-2): E. Maestrini, B. Korge, Juan Ocaña-Sierra, E. Calzolari, S. Cambiaghi, Pat Scudder, A. Hovnanian, A. Monaco, and C. Munro. A missense mutation in connexin26, d66h, causes mutilating keratoderma with sensorineural deafness (vohwinkel's syndrome) in three unrelated families. Human molecular genetics, 8 7:1237-43, Jul 1999. URL: https://doi.org/10.1093/hmg/8.7.1237, doi:10.1093/hmg/8.7.1237. This article has 401 citations and is from a domain leading peer-reviewed journal.
(sethuraman2019hereditarypalmoplantarkeratoderma pages 4-5): Gomathy Sethuraman, Tanvi Dev, and VikramK Mahajan. Hereditary palmoplantar keratoderma: a practical approach to the diagnosis. Indian Dermatology Online Journal, 10:365-379, Jul 2019. URL: https://doi.org/10.4103/idoj.idoj_367_18, doi:10.4103/idoj.idoj_367_18. This article has 45 citations.
(garciavega2021connexinsandthe pages 13-14): Laura Garcia-Vega, Erin M. O’Shaughnessy, Ahmad Albuloushi, and Patricia E. Martin. Connexins and the epithelial tissue barrier: a focus on connexin 26. Biology, 10:59, Jan 2021. URL: https://doi.org/10.3390/biology10010059, doi:10.3390/biology10010059. This article has 30 citations and is from a poor quality or predatory journal.
(garciavega2021connexinsandthe pages 4-6): Laura Garcia-Vega, Erin M. O’Shaughnessy, Ahmad Albuloushi, and Patricia E. Martin. Connexins and the epithelial tissue barrier: a focus on connexin 26. Biology, 10:59, Jan 2021. URL: https://doi.org/10.3390/biology10010059, doi:10.3390/biology10010059. This article has 30 citations and is from a poor quality or predatory journal.
(govender2023palmoplantarkeratodermapseudoainhum pages 2-4): Kellicia Courtney Govender and Somasundram Pillay. Palmoplantar keratoderma, pseudo-ainhum and knuckle pads in an african patient: a case report. SAGE Open Medical Case Reports, Jan 2023. URL: https://doi.org/10.1177/2050313x231204197, doi:10.1177/2050313x231204197. This article has 3 citations and is from a peer-reviewed journal.
(schmuth2007ichthyosisupdatetowards pages 5-6): Matthias Schmuth, Robert Gruber, Peter M. Elias, and Mary L. Williams. Ichthyosis update: towards a function-driven model of pathogenesis of the disorders of cornification and the role of corneocyte proteins in these disorders. Advances in dermatology, 23:231-56, Jan 2007. URL: https://doi.org/10.1016/j.yadr.2007.07.011, doi:10.1016/j.yadr.2007.07.011. This article has 136 citations.
(schmuth2007ichthyosisupdatetowards pages 14-15): Matthias Schmuth, Robert Gruber, Peter M. Elias, and Mary L. Williams. Ichthyosis update: towards a function-driven model of pathogenesis of the disorders of cornification and the role of corneocyte proteins in these disorders. Advances in dermatology, 23:231-56, Jan 2007. URL: https://doi.org/10.1016/j.yadr.2007.07.011, doi:10.1016/j.yadr.2007.07.011. This article has 136 citations.
(maestrini1999amissensemutation pages 6-6): E. Maestrini, B. Korge, Juan Ocaña-Sierra, E. Calzolari, S. Cambiaghi, Pat Scudder, A. Hovnanian, A. Monaco, and C. Munro. A missense mutation in connexin26, d66h, causes mutilating keratoderma with sensorineural deafness (vohwinkel's syndrome) in three unrelated families. Human molecular genetics, 8 7:1237-43, Jul 1999. URL: https://doi.org/10.1093/hmg/8.7.1237, doi:10.1093/hmg/8.7.1237. This article has 401 citations and is from a domain leading peer-reviewed journal.

{ }

Source YAML

click to show

name: Keratoderma Hereditarium Mutilans
creation_date: '2026-02-06T03:39:54Z'
updated_date: '2026-02-17T21:53:14Z'
description: >
  Keratoderma hereditarium mutilans, also known as Vohwinkel syndrome, is a rare
  autosomal dominant genodermatosis characterized by diffuse palmoplantar keratoderma
  with a distinctive honeycomb pattern, pseudoainhum (constricting bands around digits
  leading to autoamputation), and sensorineural hearing loss. The classic form is
  caused
  by mutations in the GJB2 gene encoding connexin 26. The ichthyotic variant (Camisa
  syndrome) is caused by mutations in the LOR gene encoding loricrin.
category: Mendelian
disease_term:
  preferred_term: keratoderma hereditarium mutilans
  term:
    id: MONDO:0007422
    label: keratoderma hereditarium mutilans
parents:
- Hereditary Palmoplantar Keratoderma
- Connexin Disorders
prevalence:
- population: Published literature
  percentage: Approximately 50 reported cases
  notes: >-
    No population-based prevalence estimate was identified in the PubMed-indexed
    literature reviewed. Reported epidemiology is based on case reports and small
    surgical series, consistent with an exceptionally rare genodermatosis.
  evidence:
  - reference: PMID:19282408
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Approximately 50 cases have been reported in the literature with only three having been managed surgically."
    explanation: This review provides a direct published estimate of the very small number of reported Vohwinkel syndrome cases.
has_subtypes:
- name: Classic Vohwinkel Syndrome
  description: >
    The classic form caused by GJB2 mutations, featuring the complete triad of
    palmoplantar keratoderma, pseudoainhum, and sensorineural hearing loss.
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      VS is characterized by papular and honeycomb keratoderma associated with
      constrictions of digits leading to autoamputation, distinctive starfish-like
      acral keratoses and moderate degrees of deafness.
    explanation: This landmark paper identified the D66H mutation in GJB2 as
      causative for classic Vohwinkel syndrome with the characteristic triad.
- name: Loricrin Keratoderma (Variant Vohwinkel Syndrome)
  description: >
    A variant form caused by LOR gene mutations, featuring keratoderma and pseudoainhum
    but with ichthyosis instead of hearing loss. Also known as Camisa variant.
  evidence:
  - reference: PMID:9326398
    reference_title: "Loricrin mutation in Vohwinkel's keratoderma is unique to the variant with ichthyosis."
    supports: SUPPORT
    snippet: >
      Vohwinkel's keratoderma is thus clinically and genetically heterogeneous. Only
      the variant with ichthyosis appears to be due to loricrin mutation.
    explanation: This paper established that loricrin mutations cause the
      ichthyotic variant without hearing loss.
  - reference: PMID:12072018
    reference_title: "A recurrent mutation in the loricrin gene underlies the ichthyotic variant of Vohwinkel syndrome."
    supports: SUPPORT
    snippet: >
      Functional studies in transgenic mice have shown that the accumulation of mutant
      loricrin in the nucleus appears to interfere with the later stages of epidermal
      differentiation, thereby explaining the clinical manifestations of ichthyosis,
      keratoderma and pseudoainhum.
    explanation: Confirms loricrin mutations underlie the ichthyotic variant of
      Vohwinkel syndrome.
pathophysiology:
- name: Gap Junction Dysfunction
  description: >
    Mutations in GJB2 disrupt connexin 26 function, impairing gap junction-mediated
    intercellular communication in the epidermis and cochlea. The D66H mutation occurs
    at a highly conserved residue in the first extracellular domain and may interfere
    with connexon assembly, docking, or gating properties. This leads to defective
    ion homeostasis and impaired cellular coordination during differentiation.
  cell_types:
  - preferred_term: Keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: Gap junction assembly
    term:
      id: GO:0016264
      label: gap junction assembly
  - preferred_term: Cell-cell signaling
    term:
      id: GO:0007267
      label: cell-cell signaling
  locations:
  - preferred_term: Skin of palm and sole
    term:
      id: UBERON:0013776
      label: skin of palmar/plantar part of autopod
  downstream:
  - target: Abnormal Epidermal Differentiation
    description: >
      Impaired gap junction communication disrupts calcium signaling and
      intercellular coordination required for normal keratinocyte differentiation.
    evidence:
    - reference: PMID:10369869
      reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
      supports: SUPPORT
      snippet: >
        Our results provide evidence that a specific mutation in Cx26 can impair
        epidermal differentiation, as well as inner ear function.
      explanation: Demonstrates that GJB2 mutations lead to impaired epidermal
        differentiation.
  - target: Cochlear Dysfunction
    description: >
      Connexin 26 dysfunction in the inner ear disrupts potassium recycling
      and the endocochlear potential required for hearing.
    evidence:
    - reference: PMID:10369869
      reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
      supports: SUPPORT
      snippet: >
        Mutations in the connexin26 (Cx26) gene (GJB2) at 13q11-q13 are a major cause
        of autosomal recessive hearing loss (DFNB1), but have also been reported in
        autosomal dominant deafness (DFNA3).
      explanation: Establishes the causal link between GJB2 mutations and
        hearing loss.
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      This mutation occurs at a highly conserved residue in the first extracellular
      domain of the Cx26 molecule, and may exert its effects by interfering with
      assembly into connexons, docking with adjacent cells or gating properties of
      the gap junction.
    explanation: Describes the molecular mechanism of GJB2 D66H mutation
      disrupting gap junction function.
  - reference: PMID:14681042
    reference_title: "The effects of a mutant connexin 26 on epidermal differentiation."
    supports: SUPPORT
    snippet: >
      Expression of the transgene resulted in a loss of Cx26 and Cx30 at intercellular
      junctions of epidermal keratinocytes and accumulation of these connexins in
      the
      cytoplasm.
    explanation: Transgenic mouse model demonstrates that D66H mutation causes
      loss of connexins at cell junctions.
    evidence_source: MODEL_ORGANISM
- name: Abnormal Epidermal Differentiation
  description: >
    Defective gap junction signaling leads to hyperproliferation and abnormal
    keratinization of palmoplantar epidermis, resulting in the characteristic
    thickened honeycomb-patterned skin. The mutation impairs epidermal differentiation
    as well as inner ear function.
  cell_types:
  - preferred_term: Keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: Keratinocyte differentiation
    term:
      id: GO:0030216
      label: keratinocyte differentiation
  downstream:
  - target: Digital Constriction and Autoamputation
    description: >
      Chronic aberrant keratinization leads to formation of fibrous constricting
      bands around digits that progressively tighten and may cause autoamputation.
    evidence:
    - reference: PMID:10369869
      reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
      supports: SUPPORT
      snippet: >
        VS is characterized by papular and honeycomb keratoderma associated with
        constrictions of digits leading to autoamputation
      explanation: Links the keratoderma phenotype to digital constriction and
        autoamputation.
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      Our results provide evidence that a specific mutation in Cx26 can impair
      epidermal differentiation, as well as inner ear function.
    explanation: Establishes that GJB2 mutations affect both epidermal and
      cochlear function.
  - reference: PMID:14681042
    reference_title: "The effects of a mutant connexin 26 on epidermal differentiation."
    supports: SUPPORT
    snippet: >
      Following birth, the transgenic mice developed keratoderma similar to that of
      human carriers of Cx26 (D66H).
    explanation: Transgenic mice expressing mutant Cx26 develop keratoderma like
      human patients.
    evidence_source: MODEL_ORGANISM
- name: Mutant Loricrin Nuclear Accumulation
  description: >
    In the ichthyotic variant, mutant loricrin is mislocalized to the nuclei of
    granular layer keratinocytes and fails to incorporate into the cornified cell
    envelope. The frameshift mutation creates an abnormal C-terminal peptide containing
    nuclear localization signals, causing aberrant nuclear translocation and interference
    with late stages of epidermal differentiation.
  cell_types:
  - preferred_term: Keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: Cornified envelope assembly
    term:
      id: GO:1903575
      label: cornified envelope assembly
  - preferred_term: Keratinocyte differentiation
    term:
      id: GO:0030216
      label: keratinocyte differentiation
  downstream:
  - target: Digital Constriction and Autoamputation
    description: >
      Nuclear interference with keratinocyte differentiation leads to
      defective cornification and formation of constricting bands.
    evidence:
    - reference: PMID:12072018
      reference_title: "A recurrent mutation in the loricrin gene underlies the ichthyotic variant of Vohwinkel syndrome."
      supports: SUPPORT
      snippet: >
        the accumulation of mutant loricrin in the nucleus appears to interfere
        with the later stages of epidermal differentiation, thereby explaining
        the clinical manifestations of ichthyosis, keratoderma and pseudoainhum.
      explanation: Establishes the mechanistic link between loricrin nuclear
        accumulation and pseudoainhum.
  evidence:
  - reference: PMID:11121146
    reference_title: "Mutant loricrin is not crosslinked into the cornified cell envelope but is translocated into the nucleus in loricrin keratoderma."
    supports: SUPPORT
    snippet: >
      Mutant loricrin, as a dominant negative disrupter, is not likely to affect
      cornified cell envelope crosslinking directly, but seems to interfere with
      nuclear/nucleolar functions of differentiating keratinocytes.
    explanation: Describes the mechanism by which mutant loricrin causes disease
      through nuclear interference.
  - reference: PMID:9326398
    reference_title: "Loricrin mutation in Vohwinkel's keratoderma is unique to the variant with ichthyosis."
    supports: SUPPORT
    snippet: >
      a G insertion producing a frameshift after codon 231 and an abnormal C-terminal
      peptide lacking residues necessary for cross-linking.
    explanation: Identifies the specific mutation and its effect on loricrin
      protein structure.
  - reference: PMID:11038186
    reference_title: "Transgenic mice expressing a mutant form of loricrin reveal the molecular basis of the skin diseases, Vohwinkel syndrome and progressive symmetric erythrokeratoderma."
    supports: SUPPORT
    snippet: >
      Immunofluorescence and immunoelectron microscopy showed the mutant loricrin
      protein in the nucleus and cytoplasm of epidermal keratinocytes, but did not
      detect the protein in the cornified cell envelope.
    explanation: Transgenic mouse studies confirm nuclear mislocalization of
      mutant loricrin.
    evidence_source: MODEL_ORGANISM
- name: Digital Constriction and Autoamputation
  description: >
    Fibrous bands encircle digits (pseudoainhum), progressively constricting and
    potentially leading to spontaneous amputation. The pathogenesis involves aberrant
    keratinization and tissue remodeling secondary to keratinocyte dysfunction.
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      VS is characterized by papular and honeycomb keratoderma associated with
      constrictions of digits leading to autoamputation
    explanation: Describes the progression from constricting bands to
      autoamputation.
- name: Cochlear Dysfunction
  description: >
    Connexin 26 is essential for potassium recycling in the cochlea. Its dysfunction
    disrupts the endocochlear potential required for auditory transduction, causing
    sensorineural hearing loss. This phenotype is specific to GJB2 mutations and
    is absent in the loricrin-associated variant.
  locations:
  - preferred_term: Cochlea
    term:
      id: UBERON:0001844
      label: cochlea
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      Mutations in the connexin26 (Cx26) gene (GJB2) at 13q11-q13 are a major cause
      of autosomal recessive hearing loss (DFNB1), but have also been reported in
      autosomal dominant deafness (DFNA3).
    explanation: Establishes the role of GJB2 in both skin and hearing
      phenotypes.
  - reference: PMID:9326398
    reference_title: "Loricrin mutation in Vohwinkel's keratoderma is unique to the variant with ichthyosis."
    supports: SUPPORT
    snippet: >
      In our second family (VK2), affected members had sensorineural deafness but
      not ichthyosis.
    explanation: Confirms that deafness segregates with connexin mutations, not
      loricrin mutations.
phenotypes:
- name: Palmoplantar Keratoderma
  description: >
    Diffuse thickening of the skin on palms and soles with a characteristic
    honeycomb or starfish pattern, typically appearing in infancy or early childhood.
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Palmoplantar keratoderma
    term:
      id: HP:0000982
      label: Palmoplantar keratoderma
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      VS is characterized by papular and honeycomb keratoderma associated with
      constrictions of digits leading to autoamputation
    explanation: Honeycomb keratoderma is a defining feature of the syndrome.
- name: Honeycomb Palmoplantar Hyperkeratosis
  description: >
    The characteristic honeycomb pattern of hyperkeratosis on palms and soles,
    a hallmark feature of both GJB2 and LOR forms.
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Honeycomb palmoplantar hyperkeratosis
    term:
      id: HP:0007465
      label: Honeycomb palmoplantar hyperkeratosis
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      VS is characterized by papular and honeycomb keratoderma
    explanation: Honeycomb pattern is characteristic of the syndrome.
- name: Pseudoainhum
  description: >
    Constricting fibrous bands around digits, particularly affecting the fifth toe
    and other fingers, which may progress to autoamputation.
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Autoamputation of digits
    term:
      id: HP:0007460
      label: Autoamputation of digits
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      constrictions of digits leading to autoamputation
    explanation: Pseudoainhum with potential autoamputation is a key feature.
  - reference: PMID:12072018
    reference_title: "A recurrent mutation in the loricrin gene underlies the ichthyotic variant of Vohwinkel syndrome."
    supports: SUPPORT
    snippet: >
      the clinical manifestations of ichthyosis, keratoderma and pseudoainhum
    explanation: Pseudoainhum is a feature of both genetic forms.
- name: Sensorineural Hearing Loss
  description: >
    Bilateral, progressive hearing impairment ranging from mild to profound,
    typically presenting in early childhood. Present in classic GJB2-associated
    form but absent in loricrin-associated variant.
  frequency: FREQUENT
  subtype: Classic Vohwinkel Syndrome
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      A missense mutation in connexin26, D66H, causes mutilating keratoderma with
      sensorineural deafness (Vohwinkel's syndrome) in three unrelated families.
    explanation: Sensorineural deafness is part of the classic Vohwinkel
      phenotype.
  - reference: PMID:20031451
    reference_title: "Vohwinkel Syndrome secondary to missense mutation D66H in GJB2 gene (connexin 26) can include epileptic manifestations."
    supports: SUPPORT
    snippet: >
      Vohwinkel Syndrome (VS) is a type of diffuse hereditary palmoplantar
      keratodermas (DHPPK) accompanied by skeletal dimorphisms and sensorineural
      deafness.
    explanation: Confirms sensorineural deafness as a component of the syndrome.
- name: Starfish-Shaped Hyperkeratoses
  description: >
    Distinctive star-shaped keratotic lesions on the dorsal surfaces of hands,
    feet, elbows, and knees.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hyperkeratosis
    term:
      id: HP:0000962
      label: Hyperkeratosis
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      distinctive starfish-like acral keratoses
    explanation: Starfish-like acral keratoses are a characteristic feature.
- name: Knuckle Pads
  description: >
    Thickened skin over the knuckles (interphalangeal joints), presenting
    as keratotic structures on the dorsal surfaces of the hands, often with
    a starfish-like appearance.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Knuckle pad
    term:
      id: HP:0032541
      label: Knuckle pad
  evidence:
  - reference: PMID:6237617
    reference_title: "Variant of keratoderma hereditaria mutilans (Vohwinkel's syndrome). Treatment with orally administered isotretinoin."
    supports: SUPPORT
    snippet: >
      keratotic structures taking the shape of a starfish and/or knuckle pads
      on the dorsal surfaces of the hands
    explanation: Describes starfish-shaped keratoses and knuckle pads as
      characteristic features.
  - reference: PMID:30335335
    reference_title: "Vohwinkel Syndrome."
    supports: SUPPORT
    snippet: >
      The classic Vohwinkel syndrome is a hereditary PPK associated with
      "starfish" keratoses on the knuckles
    explanation: StatPearls review confirms starfish keratoses on knuckles are
      part of classic syndrome.
- name: Ichthyosis
  description: >
    Generalized scaling of the skin, characteristic of the loricrin-associated
    (Camisa) variant but absent in classic GJB2-associated form.
  frequency: VERY_FREQUENT
  subtype: Loricrin Keratoderma (Variant Vohwinkel Syndrome)
  phenotype_term:
    preferred_term: Ichthyosis
    term:
      id: HP:0008064
      label: Ichthyosis
  evidence:
  - reference: PMID:9326398
    reference_title: "Loricrin mutation in Vohwinkel's keratoderma is unique to the variant with ichthyosis."
    supports: SUPPORT
    snippet: >
      Our first family (VK1) also had ichthyosis but not deafness.
    explanation: Ichthyosis is present in the loricrin variant but not classic
      form.
  - reference: PMID:11038186
    reference_title: "Transgenic mice expressing a mutant form of loricrin reveal the molecular basis of the skin diseases, Vohwinkel syndrome and progressive symmetric erythrokeratoderma."
    supports: SUPPORT
    snippet: >
      At birth, transgenic mice (ML.VS) exhibited erythrokeratoderma with an epidermal
      barrier dysfunction. 4 d after birth, high-expressing transgenic animals showed
      a generalized scaling of the skin
    explanation: Transgenic mice with mutant loricrin develop ichthyosis-like
      scaling.
    evidence_source: MODEL_ORGANISM
- name: Alopecia
  description: >
    Sparse hair or patchy hair loss, particularly affecting eyebrows and eyelashes
    in some patients.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Alopecia
    term:
      id: HP:0001596
      label: Alopecia
genetic:
- name: GJB2
  gene_term:
    preferred_term: GJB2
    term:
      id: hgnc:4284
      label: GJB2
  association: Causative
  notes: >
    Autosomal dominant. The D66H mutation (c.196G>C) in exon 1 is the most common
    pathogenic variant causing classic Vohwinkel syndrome. The mutation occurs at
    a highly conserved residue in the first extracellular domain of connexin 26.
  variants:
  - name: D66H
    description: >
      Missense mutation (c.196G>C) causing substitution of aspartate to histidine
      at position 66 in the first extracellular domain. Most common mutation in
      classic Vohwinkel syndrome.
  evidence:
  - reference: PMID:10369869
    reference_title: "A missense mutation in connexin26, D66H, causes mutilating keratoderma with sensorineural deafness (Vohwinkel's syndrome) in three unrelated families."
    supports: SUPPORT
    snippet: >
      All 10 affected members were heterozygous for a non-conservative mutation,
      D66H, in Cx26. The same mutation was found subsequently in affected individuals
      from two unrelated Spanish and Italian pedigrees segregating VS, suggesting
      that D66H in Cx26 is a common mutation in classical VS.
    explanation: Identifies D66H as a common mutation in classic Vohwinkel
      syndrome across multiple families.
  - reference: PMID:20031451
    reference_title: "Vohwinkel Syndrome secondary to missense mutation D66H in GJB2 gene (connexin 26) can include epileptic manifestations."
    supports: SUPPORT
    snippet: >
      Genetic study showed a nucleotide change (c.196G>C) in exon 1 of GJB2 gene,
      producing a missense mutation, D66H.
    explanation: Confirms the specific nucleotide change causing the D66H
      mutation.
- name: LOR
  gene_term:
    preferred_term: LOR
    term:
      id: hgnc:6663
      label: LOR
  association: Causative
  notes: >
    Autosomal dominant. Frameshift mutations (commonly 730insG) cause the ichthyotic
    variant (Camisa syndrome). The mutation produces an abnormal C-terminal peptide
    with nuclear localization signals.
  variants:
  - name: 730insG
    description: >
      Recurrent insertion mutation causing frameshift after codon 231, producing
      an abnormal C-terminal peptide that mislocalizes to the nucleus.
  evidence:
  - reference: PMID:9326398
    reference_title: "Loricrin mutation in Vohwinkel's keratoderma is unique to the variant with ichthyosis."
    supports: SUPPORT
    snippet: >
      a G insertion producing a frameshift after codon 231 and an abnormal C-terminal
      peptide lacking residues necessary for cross-linking.
    explanation: Identifies the specific loricrin mutation causing the
      ichthyotic variant.
  - reference: PMID:12072018
    reference_title: "A recurrent mutation in the loricrin gene underlies the ichthyotic variant of Vohwinkel syndrome."
    supports: SUPPORT
    snippet: >
      identified a recurrent insertion mutation in the loricrin gene resulting in
      a mutant polypeptide with an unusual C terminus.
    explanation: Confirms the recurrent nature of loricrin insertion mutations.
treatments:
- name: Keratolytic Therapy
  description: >
    Topical agents containing salicylic acid or urea to soften and reduce
    hyperkeratotic skin lesions on palms and soles.
- name: Emollients
  description: >
    Regular application of moisturizers to maintain skin hydration and
    reduce cracking and discomfort.
- name: Retinoids
  description: >
    Oral retinoids (isotretinoin, acitretin) may help control hyperkeratosis
    and can prevent digital constrictions in some patients. Relapse typically
    occurs upon discontinuation of treatment.
  evidence:
  - reference: PMID:6237617
    reference_title: "Variant of keratoderma hereditaria mutilans (Vohwinkel's syndrome). Treatment with orally administered isotretinoin."
    supports: SUPPORT
    snippet: >
      One of the patients was successfully treated with isotretinoin, 0.6 mg/kg/day
      orally.
    explanation: First report of successful isotretinoin treatment for the
      ichthyotic variant of Vohwinkel syndrome.
- name: Surgical Intervention
  description: >
    Surgical release of constricting bands may be necessary to prevent
    autoamputation of digits; in severe cases, amputation may be required.
- name: Hearing Aids and Cochlear Implants
  description: >
    Audiological management for sensorineural hearing loss, including
    hearing aids for mild-moderate loss and cochlear implants for profound loss.
    Applicable only to classic GJB2-associated form.
datasets:
references:
- reference: DOI:10.1016/j.yadr.2007.07.011
  title: 'Ichthyosis Update: Towards a Function-Driven Model of Pathogenesis of the
    Disorders of Cornification and the Role of Corneocyte Proteins in These Disorders'
  findings: []
- reference: DOI:10.1093/hmg/8.7.1237
  title: A missense mutation in connexin26, D66H, causes mutilating keratoderma
    with sensorineural deafness (Vohwinkel's syndrome) in three unrelated
    families
  findings: []
- reference: DOI:10.1177/2050313x231204197
  title: 'Palmoplantar keratoderma, pseudo-ainhum and knuckle pads in an African patient:
    A case report'
  findings: []
- reference: DOI:10.3390/biology10010059
  title: 'Connexins and the Epithelial Tissue Barrier: A Focus on Connexin 26'
  findings: []