Identification of a founder variant AAGAB c.370C>T, p.Arg124Ter in patients with punctate palmoplantar keratoderma in Southern Denmark

Palmoplantar keratoderma (PPK) is a heterogeneous group of rare skin diseases characterized by hyperkeratosis on the palms or soles. The subtype isolated punctate PPK is caused by heterozygous variants in AAGAB. We investigated if the variant AAGAB c.370C>T, p.Arg124Ter in patients with punctate PPK in the Region of Southern Denmark represented a founder variant and estimated the age to the most recent common ancestor. We performed haplotype analysis on samples from 20 patients diagnosed with punctate PPK and the AAGAB c.370C>T, p.Arg124Ter variant. Using the Gamma Method, we calculated the years to the most recent common ancestor. We also explored the presence of the variant in other populations through literature and databases (HGMD, ClinVar, and gnomAD). Our analysis revealed a shared haplotype of 3.0 Mb, suggesting shared ancestry. The ancestral haplogroup was estimated to an age of 12.1 generations (CI: 4.9-20.3) equivalent to approximately 339 years (CI: 137-568). This study confirms that the frequently observed variant AAGAB c.370C>T, p.Arg124Ter in punctate PPK among patients in the Region of Southern Denmark is caused by a founder variant. We recommend testing for the variant as initial screening in our region and potentially for all Danish patients presenting with punctate PPK.

Acquired diffuse palmoplantar erythema with keratoderma in Chinese patients with pustular psoriasis: A predictor for IL36 receptor antagonist c.115+6T>C mutation?

Several studies have suggested that mutation of the interleukin 36 receptor antagonist gene (IL36RN) is related to generalized pustular psoriasis (GPP), and the presence of IL36RN mutation may affect the clinical manifestations and treatment responses. However, genetic testing is not routinely available in clinical practice for the diagnosis of GPP. Previously, GPP patients with acrodermatitis continua of Hallopeau (ACH) were found to have a high percentage of carrying IL36RN mutation. In this study, we reported six patients with pustular psoriasis presenting as diffuse palmoplantar erythema with keratoderma among 60 patients who carried IL36RN mutation. ACH was present in five patients and five patients had acute flare of GPP. This unique presentation may serve as a predictor for IL36RN mutation in patients with pustular psoriasis, similar to ACH.

Spontaneous clinical remission of Nagashima-type palmoplantar keratoderma in a patient of Korean descent with a heterozygous SERPINB7 mutation

Nagashima-type palmoplantar keratoderma (NPPK) is an autosomal recessive form of diffuse palmoplantar keratoderma (PPK) characterized by thickening and redness of palms and/or soles. In this report, we describe a female patient of Korean descent who had clinical remission of her adult-onset NPPK. To our knowledge, she is the first reported heterozygous SERBINB7 mutation carrier to present with classic NPPK who achieved spontaneous clinical remission.

A Case of Palmoplantar Keratoderma in the Constellation of Connective Tissue Diseases

Overlap syndrome is a clinical challenge and brings together a wide range of treatment options for the treating physician. Addressing each and every complaint of the patient is crucial. A 50-year-old female patient presented with skin thickening, blackening, and hyperkeratosis; dysphagia; joint pain; features of myopathy; Raynaud's phenomenon; and dry mouth. Inflammatory markers were raised along with a positive antinuclear antibody (ANA) with Golgi apparatus pattern, anti-Sjögren's-syndrome-related antigen A (anti-SSA)/Ro60 3+, anti-SSA/Ro52 3+, and anti-PM/Scl 2+ antibodies that suggested overlap syndrome. Although the patient had no respiratory complaints, a unique interstitial lung disease (ILD) pattern was noted during the evaluation. Skin manifestations were puzzling, but the histopathology analyses of skin biopsies taken from two different sites revealed distinguishing features of cutaneous lupus and dermatomyositis. Treatment with hydroxychloroquine, pilocarpine, nifedipine, methotrexate, and topical tacrolimus produced a dramatic improvement in the clinical features. This case highlights subtle and florid features of different autoimmune diseases. The hyperkeratotic skin changes were the most striking feature, but the whole evaluation process unveiled many rare presentations of known autoimmune conditions that can open doors to new areas of our understanding toward connective tissue diseases (CTDs). Our case report demonstrates significant heterogeneity in the ANA patterns, ILD patterns, clinical manifestations, and treatment approaches.

A Rare Case on Capecitabine Induced Acquired Palmoplantar Keratoderma

Acquired palmoplantar keratoderma (PPK) is a non-hereditary hyperkeratosis of the palms and soles that is caused by various factors, including chemotherapeutic agents. The purpose of this case report is to present a rare case of acquired PPK caused by the chemotherapeutic agent capecitabine. A 54-year-old female complained of painful erythematous plaques on her palms and soles with history of consuming capecitabine. Physical examination revealed scaly erythematous plaques on the palmoplantar surface and knuckle pads on both hands. Histopathological features showed hyperkeratosis, acanthosis, vasodilatation, and perivascular lymphocytic infiltration. Therefore, the patient was diagnosed with acquired PPK due to capecitabine. The dose of capecitabine was reduced and the patient was administered topical corticosteroid and emollient. Improvement of skin lesions was strongly observed after discontinuation of capecitabine. The underlying cause of PPK should be identified to determine the appropriate treatment. Dose reduction or drug discontinuation is the mainstay therapy for patients with acquired PPK caused by chemotherapeutic agents.

Pachyonychia Congenita: Clinical Features and Future Treatments

Pachyonychia congenita (PC) is a rare, autosomal dominant inherited disorder of keratinization that is characterized by a triad of focal palmoplantar keratoderma, plantar pain, and hypertrophic nail dystrophy. It can be debilitating, causing significantly impaired mobility. PC is diagnosed clinically alongside identification of a heterozygous pathogenic mutation in one of five keratin genes: KRT6A, KRT6B, KRT6C, KRT16, or KRT17. Each keratin gene mutation is associated with a distinct clinical phenotype, with variable age of onset and additional features, which has allowed classification by genotype. Additional features include pilosebaceous cysts, follicular hyperkeratosis, natal teeth, oral leukokeratosis, hidradenitis suppurativa, itching, and neurovascular structures. Although classed as rare, the prevalence of PC is likely to be underestimated. There is no cure or specific treatment for PC at present. Current treatments are limited to conservative measures to reduce plantar friction and trauma, mechanical debridement, topical treatments, and treatments for associated features or complications, most commonly infection. However, through active research in collaboration with PC Project, a patient-advocacy group, and the International PC Research Registry, a global registry of PC patients, there are now many new potential therapeutic options on the horizon. This review summarizes the clinical features associated with PC and highlights the current and future treatment of its manifestations.

Unexpected Adverse Events of Immune Checkpoint Inhibitors

The introduction of immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment standards and significantly enhanced patient prognoses. However, the utilization of these groundbreaking therapies has led to the observation and reporting of various types of adverse events, commonly known as immune-related adverse events (irAEs). In the following article, we present four patients who encountered uncommon toxicities induced by ICIs. The first patient was a 59-year-old female diagnosed with stage 4 lung adenocarcinoma. She received immunotherapy (pembrolizumab) together with chemotherapy and subsequently developed autonomic neuropathy (AN). The next two patients also received chemo-immunotherapy (pembrolizumab) and were both 63-year-old males with stage 4 lung adenocarcinoma. One of the two experienced palmoplantar keratoderma, while the other presented with Reiter's syndrome (urethritis, conjunctivitis and arthritis). The 4th patient, an 80-year-old male with stage 4 squamous cell carcinoma of the lung, received chemo-immunotherapy (pembrolizumab) and developed myasthenia gravis.

Integration of Phenotype Term Prioritization and Gene Expression Analysis Reveals a Novel Variant in the PERP Gene Associated with Autosomal Recessive Erythrokeratoderma

Hereditary palmoplantar keratodermas (PPKs) are a clinically and genetically heterogeneous group of disorders characterized by excessive epidermal thickening of palms and soles. Several genes have been associated with PPK including PERP, a gene encoding a crucial component of desmosomes that has been associated with dominant and recessive keratoderma. We report a patient with recessive erythrokeratoderma (EK) in which whole exome sequencing (WES) prioritized by human phenotype ontology (HPO) terms revealed the presence of the novel variant c.153C > A in the N-terminal region the PERP gene. This variant is predicted to have a nonsense effect, p.(Cys51Ter), resulting in a premature stop codon. We demonstrated a marked reduction in gene expression in cultured skin fibroblasts obtained from the patient. Despite the PERP gene is expressed at low levels in fibroblasts, our finding supports a loss-of-function (LoF) mechanism for the identified variant, as previously suggested in recessive EK. Our study underscores the importance of integrating HPO analysis when using WES for molecular genetic diagnosis in a clinical setting, as it facilitates continuous updates regarding gene-clinical feature associations.

Biallelic mutations in LSS in autosomal-recessive mutilating palmoplantar keratoderma

Mutilating palmoplantar keratoderma (PPK) is a heterogeneous genetic disease that poses enormous challenges to clinical diagnosis and genetic counselling. Lanosterol synthase (LSS) gene encodes LSS involved in the biosynthesis pathway of cholesterol. Biallelic mutations in LSS were found to be related to diseases such as cataracts, hypotrichosis and palmoplantar keratoderma-congenital alopecia syndrome. The aim of this study was to investigate the contribution of the LSS mutation to mutilating PPK in a Chinese patient. The clinical and molecular characteristics of the patient were evaluated. A 38-year-old male patient with mutilating PPK was recruited in this study. We identified biallelic variants in the LSS gene (c.683C > T, p.Thr228Ile and c.779G > A, p.Arg260His). Immunoblotting revealed that the Arg260His mutant showed a significantly reduced expression level while Thr228Ile showed an expression level similar to that of the wild type. Thin layer chromatography revealed that mutant Thr228Ile retained partial enzymatic activity and mutant Arg260His did not show any catalytic activity. Our findings show the correlation between LSS mutations and mutilating PPK.

Punctate Palmoplantar Keratoderma: A Case Report

Palmoplantar keratoderma (PPK) is an umbrella term for a group of heterogeneous disorders, acquired or inherited, that are characterized by hyperkeratosis of palmar and/or plantar surfaces. Punctate PPK (PPPK) has been shown to have an autosomal dominant pattern of inheritance. It is linked with two loci on chromosomes 8q24.13-8q24.21 and 15q22-15q24. In type 1 PPPK, also known as Buschke-Fischer-Brauer disease, loss-of-function mutations in either the AAGAB or the COL14A1 genes have been associated with the disorder. We report here the clinical and genetic features of a patient with findings most consistent with type 1 PPPK.

Bothnian Palmoplantar Keratoderma: Further Delineation of the Associated Phenotype

Bothnian palmoplantar keratoderma (PPKB, MIM600231) is an autosomal dominant form of diffuse non-epidermolytic PPK characterized by spontaneous yellowish-white PPK associated with a spongy appearance after water-immersion. It is due to AQP5 heterozygous mutations. We report four patients carrying a novel AQP5 heterozygous mutation (c.125T>A; p.(Ile42Asn)), and belonging to the same French family. Early palmoplantar swelling (before one year of age), pruritus and hyperhidrosis were constant. The PPK was finally characterized as transgrediens, non-progrediens, diffuse PPK with a clear delineation between normal and affected skin. The cutaneous modifications at water-immersion test, "hand-in-the-bucket sign", were significantly evident after 3 to 6 min of immersion in the children and father, respectively. AQP5 protein is expressed in eccrine sweat glands (ESG), salivary and airway submucosal glands. In PPKB, gain of function mutations seem to widen the channel diameter of ESG and increase water movement. Thus, swelling seems to be induced by hypotonicity with water entrance into cells, while hyperhidrosis is the result of an increased cytosolic calcium concentration.

Palmoplantar Keratoderma: A Molecular Genetic Analysis of Family Cases

Palmoplantar keratoderma is a clinically polymorphic disorder with a heterogeneous etiology characterized by marked hyperkeratotic lesions on the surface of palms and soles. Hereditary forms of palmoplantar keratoderma usually have autosomal dominant inheritance and are caused by mutations in dozens of genes, most of which belong to the keratin family. We carried out clinical and molecular genetic analysis of the affected and healthy members of four families with autosomal dominant palmoplantar keratoderma. In three out of four family cases of autosomal dominant palmoplantar keratoderma, the following molecular genetic causes were established: in two families—previously non-described missense mutations in the AQP5 gene (NM_001651.4): c.369C>G (p.(Asn123Lys)) and c.103T>G (p.(Trp35Gly)); in one family—a described splice site mutation in the KRT9 gene (NM_000226.4): c.31T>G. In one family, the possible cause of palmoplantar keratoderma was detected—a variant in the KRT1 gene (NM_006121.4): c.931G>A (p.(Glu311Lys)).

CEDNIK syndrome with phenotypic variability

CEDNIK syndrome is a rare autosomal recessive syndrome characterized by cerebral dysgenesis, neuropathy, ichthyosis, and keratoderma of which 25 cases from 19 families have been reported to date. It is a progressive neurodegenerative disorder caused by the loss-of-function pathogenic variant of the SNAP29 gene encoding a member of the SNARE family of proteins. We describe two female siblings from a Syrian parent-related family with CEDNIK syndrome due to homozygous pathogenic variant in SNAP29 [c.223delG(p.Val75Serf*28)]. Palmoplantar keratoderma, reported as a cardinal sign in CEDNIK syndrome, was absent in both patients as of the last follow-up, and one of our patients had a verrucous venous malformation, a finding that has not been previously reported.

Dermoscopic furrow ink test of the palmar lesion in loricrin keratoderma

Palmoplantar keratodermas (PPK) comprise a heterogeneous group of keratinization disorders that gradually progress during childhood, resulting in difficulties to establish a diagnosis and to identify a candidate gene for sequencing. Dermoscopic examination with staining of palmoplantar skin using a whiteboard marker, so-called "furrow ink test", could be a useful tool for differentiation between furrow and ridge in understanding the morphological characteristics of PPK. One of the striking features in autosomal dominant loricrin keratoderma (LK) is diffuse PPK with honeycomb pattern. In this study, we performed dermoscopic furrow ink test in a Japanese family of LK with the most frequent mutation c.684dup, p.Ser229Valfs*107 in the loricrin gene. The severe lesion revealed that irregular circular hyperkeratoses were aggregated and normal structures of furrows and ridges were disrupted. To accurately describe the nature of this dermoscopic patterned skin surface, we suggest that the condition could be termed as "irregular cobblestone appearance" rather than "honeycomb pattern". Regular cobblestone appearance to maintain parallel furrow structure was observed in early or mild hyperkeratotic lesions. Eccrine sweat glands that open on the surface of ridges nearly disappeared, resulting in hypohidrosis.

Functional investigation of two simultaneous or separately segregating DSP variants within a single family support the theory of a dose-dependent disease severity

Desmoplakin (DP) is an important component of desmosomes, essential in cell–cell connecting structures in stress‐bearing tissues. Over the years, many hundreds of pathogenic variants in DSP have been associated with different cutaneous and cardiac phenotypes or a combination, known as a cardiocutaneous syndrome. Of less than 5% of the reported DSP variants, the effect on the protein has been investigated. Here, we describe and have performed RNA, protein and tissue analysis in a large family where DSP^{c.273+5G>A/c.6687delA} segregated with palmoplantar keratoderma (PPK), woolly hair and lethal cardiomyopathy, while DSP^{WT/c.6687delA} segregated with PPK and milder cardiomyopathy. hiPSC‐derived cardiomyocytes and primary keratinocytes from carriers were obtained for analysis. Unlike the previously reported nonsense variants in the last exon of DSP that bypassed the nonsense‐mediated mRNA surveillance system leading to protein truncation, variant c.6687delA was shown to cause the loss of protein expression. Patients carrying both variants and having a considerably more severe phenotype were shown to have 70% DP protein reduction, while patients carrying only c.6687delA had 50% protein reduction and a milder phenotype. The analysis of RNA from patient cells did not show any splicing effect of the c.273+5G>A variant. However, a minigene splicing assay clearly showed alternative spliced transcripts originating from this variant. This study shows the importance of RNA and protein analyses to pinpoint the exact effect of DSP variants instead of solely relying on predictions. In addition, the particular pattern of inheritance, with simultaneous or separately segregating DSP variants within the same family, strongly supports the theory of a dose‐dependent disease severity.

Dramatic improvement of lenvatinib-induced hand-foot skin reaction with 7-day oral prednisolone and acitretin

A 60-year-old man of hepatocellular carcinoma with distant metastasis underwent target therapy with lenvatinib for cancer management. Three weeks later, numerous dark violaceous to deep brownish, painful, and hyperkeratotic plaques with peeling were noted over bilateral hands and feet. Diagnosis of hand-foot skin reaction (HFSR) was made. After 7-day oral prednisolone and acitretin, hyperkeratotic plaques improved dramatically and painful condition as well got relieved. We considered the combination therapy of oral prednisolone and acitretin can be a prospective therapeutic option to reduce chances of cancer treatment being interrupted by HFSR.

Treatment of a chronic skin lesion in the lower limb in Meleda disease

Chronic venous skin lesions heal quickly with compression therapy and wound bed preparation. However, there are conditions in which the tissue repair process is more difficult, such as Meleda disease. Meleda disease is a rare genetic pathology, transmitted with an autosomal recessive gene with a prevalence of 1:100 000; it is also called palmoplantar keratoderma. In this pathology, there is a state of chronic inflammation, an alteration of the extracellular matrix and migration of fibroblasts and keratinocytes, which block the proliferative phase of the tissue repair process. Through targeted interventions and the use of bioactive dressings, it is possible to heal the venous ulcer, although this can take a long time. The authors report their experience in relation to a patient with Meleda disease and venous ulceration of seven years.

Huriez syndrome: Additional pathogenic variants supporting allelism to SMARCAD syndrome

Huriez syndrome (HRZ, OMIM181600) is a rare genodermatosis characterized by scleroatrophic hands and feet, hypoplastic nails, palmoplantar keratoderma, and predisposition to cutaneous squamous cell carcinoma (cSCC). We report herein three HRZ families from Croatia, the Netherlands, and Germany. Deep sequencing followed by Sanger validation, confirmed the presence of germline causative SMARCAD1 heterozygous pathogenic variants. All seven HRZ patients displayed hypohidrosis, adermatoglyphia, and one patient developed cSCC at 32 years of age. Two novel monoallelic germline mutations were identified which are predicted to disrupt the first exon-intron boundary of the skin-specific SMARCAD1 isoform. On the basis of phenotypic and genotypic convergence with Adermatoglyphia (OMIM136000) and Basan syndrome (OMIM129200), our results lend credence to the notion that these three Mendelian disorders are allelic. We propose adding Huriez syndrome to the previously suggested SMARCAD syndrome designation, which was originally invoked to describe the spectrum of monogenic disorders between Adermatoglyphia and Basan syndrome.

[Genetics of complex and syndromic palmoplantar keratoderma]

Palmoplantar keratodermas (PPK) comprise a heterogenous group of acquired and hereditary disorders marked by excessive thickening of the epidermis of palms and soles. Hereditary PPKs can be classified into 3 groups: 1) isolated non-syndromic PPKs; 2) complex non-syndromic PPKs associated with other ectodermal defects; and 3) syndromic PPKs associated with extracutaneous manifestations. All types of inheritance have been observed: autosomal dominant, autosomal recessive, X-linked recessive, and mitochondrial. Some of these disorders are restricted to geographic isolates. This review describes the different genetic causes of hereditary syndromic and complex PPKs for which the genes have been identified. The identification of pathogenic variants has consequences in terms of genetic counseling, appropriate medical care and follow-up, especially for PPKs predisposing to hearing loss, cardiomyopathies, benign tumors or carcinomas. In addition, the development of targeted therapies based on pathophysiology of disorders should allow a more effective treatment of these conditions in the near future.

A Case of Mal De Meleda: The Rare Presentation of Palmoplantar Keratoderma Disease

Mal de Meleda (MDM) is a rare sub-type of palmoplantar keratoderma (PPK) disease. The primary symptoms of PPK are scleroatrophy, transient keratoderma, scleroatrophic erythema, pseudoainhum around the digits, and perioral erythema. MDM is a pathology with a difficult clinical course. This case study presents two cases of MDM in siblings born out of second-degree consanguinity. The presenting complaint was the peeling of the palmar skin since birth. Both patients were treated with acitretin orally (dose: 10 mg) for three months and tretinoin (topical) for two months. The prognosis was good after three months of treatment.

The first case report of Haim Munk disease with neurological manifestations and literature review

HMS can have neurologic MS like manifestations. It is urgent to do more research and report probable unknown associations of HMS for its better management.

Drugs Associated With the Development of Palmoplantar Keratoderma: A Systematic Review

BACKGROUND

Palmoplantar keratoderma (PPK) are a heterogenous group of hereditary and acquired disorders that are characterized by excessive epidermal thickening of the palms and/or soles. PPK has been described as a rare adverse event for some medications. The aim of this systematic review was to summarize outcomes in PPK associated with various medications. This data will assist dermatologists and other healthcare providers treating patients with drug-induced PPK.

METHODS

EMBASE and MEDLINE databases were searched in accordance with PRISMA guidelines using the keyword "palmoplantar keratoderma." 40 studies met the inclusion criteria.

RESULTS

A total of 247 patients (mean age: 57.0 years) were included in the analysis. Among patients whose sex was reported, 60.3% (n = 35/58) were male. PPK most frequently developed after treatment with BRAF inhibitors (73.7%, n = 182/247), BRAF inhibitors combined with MEK1/2 inhibitors (15.4%, n = 38/247), tyrosine kinase inhibitors (TKIs) (3.2%, n = 8/247), or chemotherapy (2.4%, n = 6/247). The mean latency period between initiation of the drug and onset of PPK was 7.6 months (range: 0.25-90 months). Improvement of PPK was reported in 24 cases, with 50% (n = 12/24) achieving complete resolution and 50% (n = 12/24) achieving partial resolution. All patients who achieved complete resolution stopped the suspected drug, with a mean resolution period of 2.4 months (range: 2 weeks-6 months). The most common treatments for PPK were keratolytic treatments (n = 10) and topical corticosteroids (n = 4).

CONCLUSIONS

PPK was most frequently associated with targeted kinase inhibitors, specifically BRAF, MEK1/2, and tyrosine kinase inhibitors.

Japanese guidelines for the management of palmoplantar keratoderma

Palmoplantar keratoderma (PPK) is a collective term for keratinizing disorders in which the main clinical symptom is hyperkeratosis on the palms and soles. To establish the first Japanese guidelines approved by the Japanese Dermatological Association for the management of PPKs, the Committee for the Management of PPKs was founded as part of the Study Group for Rare Intractable Diseases. These guidelines aim to provide current information for the management of PPKs in Japan. Based on evidence, they summarize the clinical manifestations, pathophysiologies, diagnostic criteria, disease severity determination criteria, treatment, and treatment recommendations. Because of the rarity of PPKs, there are only few clinical studies with a high degree of evidence. Therefore, several parts of these guidelines were established based on the opinions of the committee. To further optimize the guidelines, periodic revision in line with new evidence is necessary.

RSPO1-mutated fibroblasts from non-tumoural areas of palmoplantar keratoderma display a cancer-associated phenotype

R-spondin (RSPO)1 is a fibroblast-secreted protein that belongs to the R-spondin protein family which is essential for reproductive organ development, epithelial stem cell renewal and cancer induction or suppression. RSPO1 gene mutations cause palmoplantar hyperkeratosis with squamous cell carcinoma (SCC) of the skin, 46XX sex reversal and true hermaphroditism. To characterize RSPO1-deficient skin fibroblasts derived from two patients with mutations in RSPO1, with palmoplantar hyperkeratosis, recurrent SCC and 46XX sex reversal, to provide further insight into disease-related skin tumourigenesis. Fibroblast cultures from non-tumoural palmoplantar skin biopsies were established to evaluate features and properties that may be altered at cancer onset, i.e. proliferation, extracellular matrix contraction and invasion, as well as TGF-β and matrix metalloproteinase (MMP) secretion. Fibroblasts demonstrated increased proliferative potential in vitro, a high level of collagen contraction and invasion by SCC cells, release of high levels of pro-inflammatory and pro-fibrotic TGF-β, and increased expression of MMP1 and MMP3. Analysis of the expression of selected proteins associated with RSPO1-activated pathways confirmed sustained activation of the TGF-β signalling pathway and indicated a loss of TGF-β inhibitory feedback. Also, treatment of fibroblasts with a recombinant RSPO1 protein aggravated this pro-inflammatory phenotype, suggesting caution in designing therapeutic strategies based on restoration of protein function. Our findings indicate that fibroblasts from RSPO1-mutated patients behave similarly to cancer-associated fibroblasts. Chronic inflammation and fibrotic changes in palmoplantar skin may play a role in SCC development and recurrence, possibly by irreversibly activating the tumourigenic phenotype of fibroblasts.

Ectodermal Dysplasia-Syndactyly Syndrome with Toe-Only Minimal Syndactyly Due to a Novel Mutation in NECTIN4: A Case Report and Literature Review

Ectodermal dysplasia-syndactyly syndrome 1 (EDSS1) is characterized by cutaneous syndactyly of the toes and fingers and abnormalities of the hair and teeth, variably associated with nail dystrophy and palmoplantar keratoderma (PPK). EDSS1 is caused by biallelic mutations in the NECTIN4 gene, encoding the adherens junction component nectin-4. Nine EDSS1 cases have been described to date. We report a 5.5-year-old female child affected with EDSS1 due to the novel homozygous frameshift mutation c.1150delC (p.Gln384ArgfsTer7) in the NECTIN4 gene. The patient presents brittle scalp hair, sparse eyebrows and eyelashes, widely spaced conical teeth and dental agenesis, as well as toenail dystrophy and mild PPK. She has minimal proximal syndactyly limited to toes 2-3, which makes the phenotype of our patient peculiar as the overt involvement of both fingers and toes is typical of EDSS1. All previously described mutations are located in the nectin-4 extracellular portion, whereas p.Gln384ArgfsTer7 occurs within the cytoplasmic domain of the protein. This mutation is predicted to affect the interaction with afadin, suggesting that impaired afadin activation is sufficient to determine EDSS1. Our case, which represents the first report of a NECTIN4 mutation with toe-only minimal syndactyly, expands the phenotypic and molecular spectrum of EDSS1.

Palmoplantar keratoderma with deafness phenotypic variability in a patient with an inherited GJB2 frameshift variant and novel missense variant

Background

Variants in the GJB2 gene encoding the gap junction protein connexin‐26 (Cx26) can cause autosomal recessive nonsyndromic hearing loss or a variety of phenotypically variable autosomal dominant disorders that effect skin and hearing, such as palmoplantar keratoderma (PPK) with deafness and keratitis–ichthyosis–deafness (KID) syndrome. Here, we report a patient with chronic mucocutaneous candidiasis, hyperkeratosis with resorption of the finger tips, profound bilateral sensorineural hearing loss, and normal hair and ocular examination. Exome analysis identified a novel missense variant in GJB2 (NM_004004.5:c.101T>A, p.Met34Lys) that was inherited from a mosaic unaffected parent in the setting of a well‐reported GJB2 loss of function variant (NM_004004.5:c.35delG, p.Gly12Valfs*2) on the other allele.

Method

Rat epidermal keratinocytes were transfected with cDNA encoding wildtype Cx26 and/or the Met34Lys mutant of Cx26. Fixed cells were immunolabeled in order to assess the subcellular location of the Cx26 mutant and cell images were captured.

Results

Expression in rat epidermal keratinocytes revealed that the Met34Lys mutant was retained in the endoplasmic reticulum, unlike wildtype Cx26, and failed to reach the plasma membrane to form gap junctions. Additionally, the Met34Lys mutant acted dominantly to wildtype Cx26, restricting its delivery to the cell surface.

Conclusion

Overall, we show the p.Met34Lys variant is a novel dominant acting variant causing PPK with deafness. The presence of a loss a function variant on the other allele creates a more severe clinical phenotype, with some features reminiscent of KID syndrome.

Case of Olmsted Syndrome with Essential Thrombocytosis Misdiagnosed as Acrodermatitis Enteropathica

Olmsted syndrome is a rare genodermatosis. Palmoplantar keratoderma and periorificial keratodermic plaques are the most important clinical findings. Additional findings associated with a large number of systems may accompany such as teeth, nail deformities, alopecia, mental retardation, and bone-joint anomalies. Therefore, it is difficult to make a differential diagnosis from other palmoplantar keratodermas. It also needs to be differentiated from acrodermatitis enteropathica because of periorificial plaques. The absence of regression in lesions with zinc treatment excludes this disease. We present here an Olmsted syndrome case with essential thrombocytosis for the first time.

A case report of severe dermatitis, allergies, and metabolic wasting (SAM syndrome)

The presence of eczema and elevated IgE in pediatric patients does not always indicate atopic dermatitis. Rare genodermatoses may share this clinical presentation and should be considered in the differential diagnosis for patients with congenital immunodeficiency and severe refractory dermatitis. We describe a case of severe dermatitis, allergies, and metabolic wasting syndrome, due to a novel mutation in DSG1 gene, an additional example of this uncommon genetic disorder of desmosome function.

Abnormal keratinization and cutaneous inflammation in Mal de Meleda

Mal de Meleda (MDM) is a rare, autosomal recessive form of palmoplantar keratoderma due to mutations in the gene, encoding for secreted lymphocyte antigen 6/urokinase-type plasminogen activator receptor related protein 1 (SLURP1). We report a four-year-old Taiwanese MDM female case whose biopsy specimen of hyperkeratotic lesions showed abnormal keratinization and cutaneous inflammation with characteristic transmission electron microscopic (TEM) findings and immunostaining results. The patient presented with pruritic and severely hyperkeratotic plaques on the bilateral palms and soles whichwere fringed with erythematous scaly areas. A homozygous c.256 G>A mutation, predicting a conversion of p.Gly86Arg, in SLURP1gene was detected. Histopathological examinations showed marked hyperkeratosis, acanthosis and hypergranulosis in the epidermis, accompanied by perivascular lymphocytic infiltrates in the dermis. The whole layers of the epidermis and perivascular infiltrates of the dermis were stained positive with anti-tumor necrosis factor alpha (TNFα) antibody in the biopsy specimen from the sole and the ankle. TEM examination of the biopsy specimen from the plantar hyperkeratotic plaque showed various-sized vacuoles surrounding nuclei of many keratinocytes in the spinous layer. In addition, there were numerous irregular keratohyaline granules in the granular layer. Several microorganisms and many lipid-like droplets were found in the thickened cornified layer. SLURP1 protein is known as a marker of late differentiation, predominantly expressed in the granular layer, and also known to have an inhibitory effect on TNFα release. Our results exhibited excessive TNFα expression in keratinocytes and perivascular infiltrates of the dermis, and several characteristic morphological observations of keratinocytes in MDM.

Palmoplantar keratoderma, oral involvement, and homozygous CTSC mutation in two brothers from Cambodia

Haim-Munk syndrome (HMS) and Papillon-Lefevre syndrome (PLS) are phenotypic variants of palmoplantar keratoderma (PPK) with progressive early-onset periodontitis and dental caries. HMS and PLS have been associated with homozygous or compound heterozygous mutations in the lysosomal protease gene Cathepsin C (CTSC). There have been only a few documented cases of CTSC mutations in patients from South-East Asia. We report the clinical findings of two Cambodian brothers who presented with diffuse, demarcated PPK with transgrediens extending to the elbows and knees, as well as pachyonychia and dental caries. Arachnodactyly and periodontitis were also found in the older brother. Next-generation sequencing unveiled a homozygous missense variant in CTSC (NM_001814.5: c.1337AC: p.(Asp446Ala)) in both brothers. Both parents were heterozygous for the variant, while an unaffected older brother was homozygous for the wild-type allele. Our study adds to the spectrum of mutations and associated clinical presentations for this rare genodermatosis.

Pathogenic FAM83G palmoplantar keratoderma mutations inhibit the PAWS1:CK1α association and attenuate Wnt signalling

Background: Two recessive mutations in the FAM83G gene, causing A34E and R52P amino acid substitutions in the DUF1669 domain of the PAWS1 protein, are associated with palmoplantar keratoderma (PPK) in humans and dogs respectively. We have previously reported that PAWS1 associates with the Ser/Thr protein kinase CK1α through the DUF1669 domain to mediate canonical Wnt signalling. Methods: Co-immunoprecipitation was used to investigate possible changes to PAWS1 interactors caused by the mutations. We also compared the stability of wild-type and mutant PAWS1 in cycloheximide-treated cells. Effects on Wnt signalling were determined using the TOPflash luciferase reporter assay in U2OS cells expressing PAWS1 mutant proteins. The ability of PAWS1 to induce axis duplication in Xenopus embryos was also tested. Finally, we knocked-in the A34E mutation at the native gene locus and measured Wnt-induced AXIN2 gene expression by RT-qPCR. Results: We show that these PAWS1 ^A34E and PAWS1 ^R52P mutants fail to interact with CK1α but, like the wild-type protein, do interact with CD2AP and SMAD1. Like cells carrying a PAWS1 ^F296A mutation, which also abolishes CK1α binding, cells carrying the A34E and R52P mutants respond poorly to Wnt signalling to an extent resembling that observed in FAM83G gene knockout cells. Consistent with this observation, these mutants, in contrast to the wild-type protein, fail to induce axis duplication in Xenopus embryos. We also found that the A34E and R52P mutant proteins are less abundant than the native protein and appear to be less stable, both when overexpressed in FAM83G-knockout cells and when knocked-in at the native FAM83G locus. Ala ³⁴ of PAWS1 is conserved in all FAM83 proteins and mutating the equivalent residue in FAM83H (A31E) also abolishes interaction with CK1 isoforms. Conclusions: We propose that mutations in PAWS1 cause PPK pathogenesis through disruption of the CK1α interaction and attenuation of Wnt signalling.

Clinical and molecular analysis in Papillon-Lefèvre syndrome

Papillon-Lefèvre syndrome (PLS; MIM#245000) is a rare recessive autosomal disorder characterized by palmar and plantar hyperkeratosis, and aggressively progressing periodontitis leading to premature loss of deciduous and permanent teeth. PLS is caused by loss-of-function mutations in the CTSC gene, which encodes cathepsin C. PLS clinical expressivity is highly variable and no consistent genotype-phenotype correlation has been demonstrated yet. Here we report the clinical and genetic features of five PLS patients presenting a severe periodontal breakdown in primary and permanent dentition, hyperkeratosis over palms and soles, and recurrent sinusitis and/or tonsillitis. Mutation analysis revealed two novel homozygous recessive mutations (c.947T>C and c.1010G>C) and one previous described homozygous recessive mutation (c.901G>A), with parents carrying them in heterozygous, in three families (four patients). The fourth family presented with the CTSC c.628C>T mutation in heterozygous, which was inherited maternally. Patient carrying the CTSC c.628C>T mutation featured classical PLS phenotype, but no PLS clinical characteristics were found in his carrier mother. All mutations were found to affect directly (c.901G>A, c.947T>C, and c.1010G>C) or indirectly (c.628C>T, which induces a premature termination) the heavy chain of the cathepsin C, the region responsible for activation of the lysosomal protease. Together, these findings indicate that both homozygous and heterozygous mutations in the cathepsin C heavy chain domain may lead to classical PLS phenotype, suggesting roles for epistasis or gene-environment interactions on determination of PLS phenotypes.

Novel RSPO1 mutation causing 46,XX testicular disorder of sex development with palmoplantar keratoderma: A review of literature and expansion of clinical phenotype

Palmoplantar hyperkeratosis with squamous cell carcinoma of skin and sex reversal (MIM # 610644) is a clinically distinctive form of SRY-negative 46,XX disorder of sex development. It is a rare autosomal recessive disorder caused due to biallelic loss of function mutations in RSPO1 gene. RSPO1 acts by activating the canonical β-catenin pathway and is one of the most important genes controlling female gonadal differentiation. RSPO1-associated disorders of sex development have been described only in three instances in the past. We report fourth such case with additional findings and perform a comparative review of previous phenotypic descriptions, thereby expanding the clinical phenotype of this syndrome.

Hereditary Palmoplantar Keratoderma: A Practical Approach to the Diagnosis

The ridged skin of the palms and soles has several unique features: (i) presence of dermatoglyphics created by alternating ridges and grooves forming a unique pattern, (ii) presence of the highest density of eccrine sweat glands and absence of pilosebaceous units, and (iii) differential expression of keratins compared to the glabrous skin. These features explain the preferential localization of palmoplantar keratoderma (PPK) and several of its characteristic clinical features. PPK develops as a compensatory hyperproliferation of the epidermis and excessive production of stratum corneum in response to altered cornification of the palmoplantar skin due to mutations in the genes encoding several of the proteins involved in it. PPK can manifest as diffuse, focal, striate, or punctate forms per se or as a feature of several dermatological or systemic diseases. There is a wide genetic and phenotypic heterogeneity in hereditary PPK, due to which reaching an accurate diagnosis only on the basis of clinical features may be sometimes challenging for the clinicians in the absence of molecular studies. Nevertheless, recognizing the clinical patterns of keratoderma, extent of involvement, degree of mutilation, and associated appendageal and systemic involvement may help in delineating different forms. Molecular studies, despite high cost, are imperative for accurate classification, recognizing clinical patterns in resource poor settings is important for appropriate diagnosis, genetic counseling, and management. This review intends to develop a practical approach for clinical diagnosis of different types of hereditary PPK with reasonable accuracy.

Improvement of hereditary palmoplantar keratoderma with oral trametinib

We report a child with a past medical history notable for congenital deafness, palmoplantar keratoderma (PPK), and hypothalamic glioma who initiated a MEK inhibitor trametinib for cancer-directed therapy at 11 years of age and was incidentally noted to have marked improvement in his PPK. Trametinib withdrawal led to worsening in the patient's PPK. We speculate that the patient's PPK improved because of trametinib, given the temporal relationship between trametinib therapy and PPK severity, observed both after introduction and withdrawal of trametinib therapy. The upregulation of MAPK signaling may be involved in the pathogenesis of keratinocyte proliferation in at least some forms of PPK, given that downstream inhibition of MAPK signaling led to an improvement in the patient's PPK.

Pathogenic FAM83G palmoplantar keratoderma mutations inhibit the PAWS1:CK1α association and attenuate Wnt signalling

Background: Two recessive mutations in the FAM83G gene, causing A34E and R52P amino acid substitutions in the DUF1669 domain of the PAWS1 protein, are associated with palmoplantar keratoderma (PPK) in humans and dogs respectively. We have previously reported that PAWS1 associates with the Ser/Thr protein kinase CK1α through the DUF1669 domain to mediate canonical Wnt signalling. Methods: Co-immunoprecipitation was used to investigate possible changes to PAWS1 interactors caused by the mutations. We also compared the stability of wild-type and mutant PAWS1 in cycloheximide-treated cells. Effects on Wnt signalling were determined using the TOPflash luciferase reporter assay in U2OS cells expressing PAWS1 mutant proteins. The ability of PAWS1 to induce axis duplication in Xenopus embryos was also tested. Finally, we knocked-in the A34E mutation at the native gene locus and measured Wnt-induced AXIN2 gene expression by RT-qPCR. Results: We show that these PAWS1 ^A34E and PAWS1 ^R52P mutants fail to interact with CK1α but, like the wild-type protein, do interact with CD2AP and SMAD1. Like cells carrying a PAWS1 ^F296A mutation, which also abolishes CK1α binding, cells carrying the A34E and R52P mutants respond poorly to Wnt signalling to an extent resembling that observed in FAM83G gene knockout cells. Consistent with this observation, these mutants, in contrast to the wild-type protein, fail to induce axis duplication in Xenopus embryos. We also found that the A34E and R52P mutant proteins are less abundant than the native protein and appear to be less stable, both when overexpressed in FAM83G-knockout cells and when knocked-in at the native FAM83G locus. Ala ³⁴ of PAWS1 is conserved in all FAM83 proteins and mutating the equivalent residue in FAM83H (A31E) also abolishes interaction with CK1 isoforms. Conclusions: We propose that mutations in PAWS1 cause PPK pathogenesis through disruption of the CK1α interaction and attenuation of Wnt signalling.

Patient with Mal de Meleda in whom a Novel Gene Mutation was Identified

Mal de Meleda, also known as keratoderma palmoplantaris transgrediens, is a rare type of autosomal recessive palmoplantar keratoderma. A 19-year-old male presented with a congenital yellowish discoloration and thickening of both palms and soles of the feet. His family history revealed that there was no consanguinity between the mother and the father and that the patient had three healthy brothers. The second- and third-degree relatives, five females and one male, also exhibited similar skin findings. From the isolated DNA samples, the extrinsic regions of the SLURP1 gene were screened using the sequence analysis and the Sanger sequencing was performed with the 3130 Sequence Analyzer. Results of this analysis show that a p.Arg 96 Pro (R96P) (c.287 CGA>CCA) homozygous missense point mutation was detected on the SLURP 1 (a secreted toxin-like mammalian lymphocyte antigen 6/urokinase-type plasminogen activator receptor-related protein 1) gene of the patients, while heterozygous p.Arg 96 Pro (R96P) (c.287 CGA>CCA) mutation was detected in the mother, father, and brothers. Our search of the Human Genome Mutation Database and previous literature revealed no reports of this mutation in mal de Meleda. We report this case due to the identification of a novel gene mutation in a patient with mal de Meleda, a palmoplantar keratoderma.