Erythrokeratodermia variabilis (EKV) is a rare genodermatosis characterized by well-demarcated erythematous patches and hyperkeratotic plaques. EKV is most often transmitted in an autosomal dominant manner. Until recently, only mutations in connexins such as GJB3 (connexin 31), GJB4 (connexin 30.3), and occasionally GJA1 (connexin 43) were known to cause EKV. In recent years, mutations in other genes have been described as rare causes of EKV, including the genes KDSR, KRT83, and TRPM4. Features of the EKV phenotype can also appear with other genodermatoses: for example, in Netherton syndrome, which hampers correct diagnosis. However, in autosomal recessive congenital ichthyosis (ARCI), an EKV phenotype has rarely been described. Here, we report on seven patients who clinically show a clear EKV phenotype, but in whom molecular genetic analysis revealed biallelic mutations in ABCA12, which is why the patients are classified in the ARCI group. Our study indicates that ARCI should be considered as a differential diagnosis in EKV.

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Ichthyoses are genetically determined cornification disorders of the epidermis characterized by the presence of different degrees of scaling, hyperkeratosis, and erythroderma often associated with palmoplantar keratoderma. Different classifications of these diseases have been proposed, often based upon the involved genes and/or the clinical presentation. The clinical features of these diseases present some overlap of phenotypes among distinct genetic entities, depending mainly on the penetrance of mutations. In this study, using a clinical, genetic, and molecular approach, we analyzed a family with two affected members who had clinical and histological features resembling erythrokeratodermia variabilis (EKV) or a type of erythrodermic hyperkeratosis with palmoplantar keratoderma. Despite of the clinical presentation, we demonstrated that the affected patients were genetically double heterozygous for two different mutations in the ABCA12 gene, known to be responsible for harlequin ichthyosis. To explain the mild phenotype of our patients, we performed a molecular characterization of the skin. In the upper layers of the epidermis, the results showed a patchy presence of the glucosyl-ceramides (GlcCer), which is the lipid transported by ABCA12, fundamental in contributing to skin impermeability. Indeed, the two mutations detected do not completely abolish ABCA12 activity, indicating that the mild phenotype is due to a partial loss of function of the enzyme, thus giving rise to an intermediate phenotype resembling EKVP, due to a partial depletion of GlcCer deposition.

Comel-Netherton syndrome, or Netherton syndrome (NS), is a rare chronic genetic skin condition affecting the daily life of patients, which often results in poorly developed social skills and anxiety. Genetic predisposition plays a key role alongside the clinical findings, and clinicians must be aware of it as it can mimic other well-known skin conditions. Diagnosis is challenging both clinically and histologically. Clinically, it can mimic a severe form of atopic dermatitis, psoriasiform dermatitis overlapping with atopic dermatitis, or erythrokeratodermia variabilis. The difficulties in making histological diagnosis are similar, and it is often necessary to take several biopsies in order to clarify the diagnosis. Although retinoids are used for both psoriasis, erythrokeratodermia variabilis, and other congenital forms of keratodermia, the recommended treatment doses are different. This often results in poor treatment outcome. We present a 16-year-old patient previously diagnosed as erythrokeratodermia variabilis and treated with little to no improvement. Systemic therapy with acitretin 10 mg daily, local pimecrolimus 1%, emollients, and bilastine 20 mg once daily was initiated. Due to the limited application of retinoids and the difficulties in achieving permanent remission, modern medicine is faced with the challenge of seeking innovative therapeutic solutions. New hopes are placed on targeted or anti-cytokine therapy, based on inhibiting the inflammatory component of the disease. This article is mainly focused on innovative therapeutic options, including modern medications such as dupilumab, infliximab, secukinumab, anakinra, omalizumab, and others.
UNASSIGNED: Das Comel-Netherton-Syndrom oder Netherton-Syndrom (NS) ist eine seltene chronische genetische Hauterkrankung, die das tägliche Leben der Patienten beeinträchtigt und häufig zu schlecht entwickelten sozialen Fähigkeiten und Angstzuständen führt. Die genetische Veranlagung spielt neben den klinischen Befunden eine Schlüsselrolle, und Ärzte müssen sich darüber im Klaren sein, da sie andere bekannte Hauterkrankungen nachahmen kann. Die Diagnose ist sowohl klinisch als auch histologisch eine Herausforderung. Klinisch kann es eine schwere Form von atopischer Dermatitis, psoriasiformer Dermatitis mit Überlappung mit atopischer Dermatitis oder Erythrokeratodermia variabilis nachahmen. Ähnlich sind die Schwierigkeiten bei der histologischen Diagnosestellung – oft müssen mehrere Biopsien entnommen werden, um die Diagnose zu klären. Obwohl Retinoide sowohl bei Psoriasis als auch bei Erythrokeratodermia variabilis und anderen angeborenen Formen der Keratodermie eingesetzt werden, sind die empfohlenen Behandlungsdosen unterschiedlich. Dies führt oft zu einem schlechten Behandlungsergebnis. Es wird der Fall einer 16-jährigen Patientin vorgestellt, bei der zuvor Erythrokeratodermia variabilis diagnostiziert und mit wenig bis keiner Besserung behandelt wurde. Eine systemische Therapie mit Acitretin 10 mg täglich, lokalem Pimecrolimus 1 %, Emolienzien und Bilastin 20 mg einmal täglich wurde eingeleitet. Weil Retinoide nur begrenzt angewendet werden können und wegen der Schwierigkeit, eine dauerhafte Remission zu erreichen, steht die moderne Medizin vor der Herausforderung, nach innovativen therapeutischen Lösungen zu suchen. Neue Hoffnungen werden auf die zielgerichtete oder Anti-Zytokin-Therapie gesetzt, die auf der Hemmung der entzündlichen Komponente der Krankheit basiert. Der Artikel konzentriert sich hauptsächlich auf die innovativen therapeutischen Optionen, einschließlich moderner Medikamente wie Dupilumab, Infliximab, Secukinumab, Anakinra, Omalizumab und andere.

The FA Elongase-4 (ELOVL4) enzyme mediates biosynthesis of both very long chain (VLC)-PUFAs and VLC-saturated FA (VLC-SFAs). VLC-PUFAs play critical roles in retina and sperm function, whereas VLC-SFAs are predominantly associated with brain function and maintenance of the skin permeability barrier. While some ELOVL4 mutations cause Autosomal Dominant Stargardt-like Macular Dystrophy (STGD3), other ELOVL4 point mutations, such as L168F and W246G, affect the brain and/or skin, leading to Spinocerebellar Ataxia-34 (SCA34) and Erythrokeratodermia variabilis. The mechanisms by which these ELOVL4 mutations alter VLC-PUFA and VLC-SFA biosynthesis to cause the different tissue-specific pathologies are not well understood. To understand how these mutations alter VLC-PUFA and VLC-SFA biosynthesis, we expressed WT-ELOVL4, L168F, and W246G ELOVL4 variants in cell culture and supplemented the cultures with VLC-PUFA or VLC-SFA precursors. Total lipids were extracted, converted to FA methyl esters, and quantified by gas chromatography. We showed that L168F and W246G mutants were capable of VLC-PUFA biosynthesis. W246G synthesized and accumulated 32:6n3, while L168F exhibited gain of function in VLC-PUFA biosynthesis as it made 38:5n3, which we did not detect in WT-ELOVL4 or W246G-expressing cells. However, compared with WT-ELOVL4, both L168F and W246G mutants were deficient in VLC-SFA biosynthesis, especially the W246G protein, which showed negligible VLC-SFA biosynthesis. These results suggest VLC-PUFA biosynthetic capabilities of L168F and W246G in the retina, which may explain the lack of retinal phenotype in SCA34. Defects in VLC-SFA biosynthesis by these variants may be a contributing factor to the pathogenic mechanism of SCA34 and Erythrokeratodermia variabilis.

Background: Gap junctions formed by connexins are channels on cytoplasm functioning in ion recycling and homeostasis. Some members of connexin family including connexin 31 are significant components in human skin and cochlea. In clinic, mutations of connexin 31 have been revealed as the cause of a rare hereditary skin disease called erythrokeratodermia variabilis (EKV) and non-syndromic hearing loss (NSHL). Objective: To determine the underlying genetic cause of EKV, ichthyosis and NSHL in three members of a Chinese pedigree and skin histologic characteristics of the EKV patient. Methods: By performing whole exome sequencing (WES), Sanger sequencing and skin biopsy, we demonstrate a Chinese pedigree carrying a mutation of GJB3 with three patients separately diagnosed with EKV, ichthyosis and NSHL. Results: The proband, a 6-year-old Chinese girl, presented with demarcated annular red-brown plaques and hyperkeratotic scaly patches on her trunk and limbs. Her mother has ichthyosis with hyperkeratosis and geographic tongue while her younger brother had NSHL since birth. Mutation analysis revealed all of them carried a heterozygous missense mutation c.293G>A of GJB3. Skin biopsy showed many grain cells with dyskeratosis in the granular layer. Acanthosis, papillomatosis, and a mild superficial perivascular lymphocytic infiltrate were observed. Conclusion: A mutation of GJB3 associated with EKV, ichthyosis and NSHL is reported in this case. The daughter with EKV and the son with NSHL in this Chinese family inherited the mutation from their mother with ichthyosis. The variation of clinical features may involve with genetic, epigenetic and environmental factors.

BACKGROUND Annular epidermolytic ichthyosis is a rare form of epidermolytic ichthyosis caused by specific pathogenic variants of KRT1 and KRT10. Classically, it manifests at birth with variable degrees of erythroderma and superficial erosions, which subsequently improve with time. Later, it is characterized by a cyclic history of annular hyperkeratotic erythematous plaques over the trunk and proximal extremities, with or without palmoplantar keratoderma. Greither syndrome, another autosomal dominant disorder of KRT1 mutation, is demonstrated by the diffuse, thick, scaly yellow PPK with transgrediens and erythematous border extending up to the Achilles\' tendon, patchy hyperkeratotic plaques over the knees, shins, thighs, elbows, knuckles, and axillary folds. We describe a patient with clinical findings consistent with annular epidermolytic ichthyosis mimicking Greither disease with a likely associated pathogenic variant of KRT1. CASE REPORT A 3-year-old Saudi girl presented with a diffuse palmoplantar keratoderma (PPK) extending to the dorsal aspects of the hands and feet up to the Achilles\' tendon, first noticed at the age of 3 months, with a history of recurrent coin-shaped erythematous crusted erosions over the trunk, which were spontaneously healed over time, and an associated history of hyperhidrosis. Patchy hyperkeratotic plaques were noticed upon further examination over the bilateral elbows, axillary folds, and oral commissures. CONCLUSIONS The phenotype of our patient is consistent with the clinical features described for AEI, making the new K1 variant a likely pathogenic variant. When K1 mutation is the causative variant of the disease expression, phenotypically, it can present with Greither-like PPK.

Although inherited GJA1 (encoding Cx43) gene mutations most often lead to oculodentodigital dysplasia and related disorders, four variants have been linked to erythrokeratodermia variabilis et progressiva (EKVP), a skin disorder characterized by erythematous and hyperkeratotic lesions. While two autosomal-dominant EKVP-linked GJA1 mutations have been shown to lead to augmented hemichannels, the consequence(s) of keratinocytes harboring a de novo P283L variant alone or in combination with a de novo T290N variant remain unknown. Interestingly, these variants reside within or adjacent to a carboxy terminus polypeptide motif that has been shown to be important in regulating the internalization and degradation of Cx43. Cx43-rich rat epidermal keratinocytes (REKs) or Cx43-ablated REKs engineered to express fluorescent protein-tagged P283L and/or T290N variants formed prototypical gap junctions at cell-cell interfaces similar to wildtype Cx43. Dye coupling and dye uptake studies further revealed that each variant or a combination of both variants formed functional gap junction channels, with no evidence of augmented hemichannel function or induction of cell death. Tracking the fate of EKVP-associated variants in the presence of the protein secretion blocker brefeldin A, or an inhibitor of protein synthesis cycloheximide, revealed that P283L or the combination of P283L and T290N variants either significantly extended Cx43 residency on the cell surface of keratinocytes or delayed its degradation. However, caution is needed in concluding that this modest change in the Cx43 life cycle is sufficient to cause EKVP, or whether an additional underlying mechanism or another unidentified gene mutation is contributing to the pathogenesis found in patients. This question will be resolved if further patients are identified where whole exome sequencing reveals a Cx43 P283L variant alone or, in combination with a T290N variant, co-segregates with EKVP across several family generations.

Erythrokeratodermia variabilis (EKV) is a rare disorder of cornification usually associated with dominant mutations in the GJB3 and GJB4 genes encoding connexins (Cx)31 and 30.3. Genetic heterogeneity of EKV has already been suggested. We investigated at the clinical and genetic level a consanguineous Tunisian family with 2 sisters presenting an autosomal recessive form of EKV to better characterize this disease. Mutational analysis initially screened the connexin genes and Whole-exome sequencing (WES) was performed to identify the molecular aetiology of the particular EKV phenotype in the proband. Migratory shaped erythematous areas are the initial presenting sign followed by relatively stable hyperkeratotic plaques are the two predominates characteristics in both patients. However, remarkable variability of morphological and dominating features of the disease were observed between patients. In particular, the younger sister (proband) exhibited ichthyosiform-like appearance suggesting Autosomal Recessive Congenital Ichthyosis (ARCI) condition. No causative mutations were detected in the GJB3 and GJB4 genes. WES results revealed a novel missense homozygous mutation in NIPAL4 gene (c.835C>G, p.Pro279Ala) in both patients. This variant is predicted to be likely pathogenic. In addition, in silico analysis of the mutated 3D domain structure predicted that this variant would result in NIPA4 protein destabilization and Mg2+ transport perturbation, pointing out the potential role of NIPAL4 gene in the development and maintenance of the barrier function of the epidermis. Taken togheter, these results expand the clinical phenotype associated with NIPAL4 mutation and reinforce our hypothesis of NIPAL4 as the main candidate gene for the EKV-like ARCI phenotype.

Progressive symmetric erythrokeratodermia (PSEK) comprises a group of clinically and genetically heterogeneous diseases. Previous research have identified GJB3 and GJB4 as the leading genetic causes of this disorder. With the rapid development of genetics, GJA1, KDSR, KRT83 and TRPM4 have been identified as the new causative genes for PSEK, leading to a further understanding of its clinical features and genetic mechanisms. It\'s worth noting that Nagashima-type palmoplantar keratosis was often misdiagnosed as PSEK by our domestic dermatologists. Due to the identification of SERPINB7 as the causative gene of Nagashima-type palmoplantar keratosis recently, differentiation between the two disorders could be easily distinguished.
进行性对称性红斑角化症（PSEK）包含一组临床及遗传学异质性较强的疾病，既往研究认为GJB3和GJB4是其主要致病基因。随着遗传学研究快速进展，国内外团队近年陆续发现PSEK的全新致病基因GJA1、KDSR、KRT83、TRPM4，促使PSEK的临床特征和遗传学发病机制得到进一步认识。值得注意的是，我国皮肤科医生既往普遍将长岛型掌跖角化症误诊为PSEK，随着长岛型掌跖角化症致病基因被发现，两种疾病的区别应逐步得到认识。.