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Annular epidermolytic ichthyosis is a rare subtype of epidermolytic ichthyosis that is characterized by erythematous, polycyclic, and migratory scaly plaques accompanied by palmoplantar keratoderma. This report presents the case of an 8-year-old girl who developed migratory, erythematous, scaly plaques associated with palmoplantar keratoderma. The initial hypothesis was erythrokeratodermia variabilis et progressiva; however, the finding of epidermolytic hyperkeratosis in histopathological examination led to the diagnosis of annular epidermolytic ichthyosis.

Mohamad et al. (2020) describe loss-of-function mutations in SERPINA12 as a cause of diffuse, transgradient palmoplantar keratoderma (PPK). This disorder shares similar clinical features with other PPKs caused by protease overactivity, including erythema, peeling, and exacerbation on water exposure. Understanding this disorder may shed further light on the role of proteases and their inhibitors in epidermal physiology.

Investigation of genetic determinants of Mendelian skin disorders has substantially advanced understanding of epidermal biology. Here we show that mutations in PERP, encoding a crucial component of desmosomes, cause both dominant and recessive human keratoderma. Heterozygosity for a C-terminal truncation, which produces a protein that appears to be unstably incorporated into desmosomes, causes Olmsted syndrome with severe periorificial and palmoplantar keratoderma in multiple unrelated kindreds. Homozygosity for an N-terminal truncation ablates expression and causes widespread erythrokeratoderma, with expansion of epidermal differentiation markers. Both exhibit epidermal hyperproliferation, immature desmosomes lacking a dense midline observed via electron microscopy, and impaired intercellular adhesion upon mechanical stress. Localization of other desmosomal components appears normal, which is in contrast to other conditions caused by mutations in genes encoding desmosomal proteins. These discoveries highlight the essential role of PERP in human desmosomes and epidermal homeostasis and further expand the heterogeneous spectrum of inherited keratinization disorders.

Pachyonychia congenita (PC) is a genetic disorder of keratin that presents with nail dystrophy, painful palmoplantar keratoderma, and other clinical manifestations. We investigated the genotype‒structurotype‒phenotype correlations seen with mutations in keratin genes (keratin [K]6A, K6B, K6C, K16, K17) and utilized protein structure modeling of high-frequency mutations to examine the functional importance of keratin structural domains in PC pathogenesis. Participants of the International PC Research Registry underwent genetic testing and completed a standardized survey on their symptoms. Our results support previous reports associating oral leukokeratosis with K6A mutations and cutaneous cysts, follicular hyperkeratosis, and natal teeth with K17 mutations. Painful keratoderma was prominent with K6A and K16 mutations. Nail involvement was most common in patients with K6A mutation and least common in those with K6C mutation. Across keratin subtypes, patients with coil 2B mutations had the greatest impairment in ambulation, and patients with coil 1A mutations reported more emotional issues. Molecular modeling demonstrated that hotspot missense mutations in PC largely disrupted hydrophobic interactions or surface charge. The former may destabilize keratin dimers/tetramers, whereas the latter likely interferes with higher-order keratin filament formation. Understanding the pathologic alterations in keratin structure improves our knowledge of how PC genotype correlates with clinical phenotype, advancing insight into disease pathogenesis and therapeutic development.

Summary Background Pachydermoperiostosis is a rare autosomal recessive genetic disorder characterized by the association of periostosis and pachydermia. To date, two genes involved in prostaglandin metabolism, HPGD and SLCO2A1, have been identified. Patients and methods A 7-year-old girl presented digital clubbing of the hands and feet, curved nails, hyperhidrosis, and pachydermia, as well as eczema of the trunk and limbs. The diagnosis of pachydermoperiostosis was confirmed by the detection of a homozygous mutation in the HPGD gene. The second case concerned a 41-year-old male with acral and cephalic pachydermia (cutis verticis gyrata), and palmoplantar keratoderma. Bone X-rays showed changes in the distal ends of several bones. The diagnosis of pachydermoperiostosis was confirmed by the detection of a homozygous mutation in the SLCO2A1 gene. Discussion The genotype/phenotype correlation suggests that patients with SLCO2A1 mutations will develop the symptoms later in life, but that these will be more severe, with a greater likelihood of cutis verticis gyrata and joint involvement compared with patients presenting HPGD mutations. In addition, hereditary enteropathy has recently been described in patients with SLCO2A1 mutations, which could account for the gastrointestinal picture seen in the second patient. Finally, on account of cases involving myelofibrosis associated with mutations in the SLCO2A gene, these patients should have a hematologic follow-up. Conclusion Given the genotype/phenotype correlations illustrated by these cases, it would appear useful to propose molecular diagnosis for patients presenting pachydermoperiostosis.

Background Dermatophytoses are skin superficial mycoses in which clinical manifestations are directly related to the virulence of the infecting microorganism or the host immunity. Case report We describe a severe case of dermatophytosis associated with exfoliative erythroderma, substantial palmoplantar keratoderma, onychodystrophy affecting all nails, diffuse non-scarring alopecia and tissue fungal invasion by Trichophyton tonsurans, which led us to the diagnosis of AIDS. Direct examination and culture for fungi from skin scraping from two different sites were performed. Biopsy and histopathological exam were also performed on three different sites. Direct examination of the lesions’ scraping revealed septate hyaline hyphae and arthroconidia, identified as Trichophyton tonsurans by culture in glucose Sabouraud agar and Mycosel agar. A scalp biopsy revealed follicular fungal invasion and Majocchi's granuloma. Due to the severity of the presentation we requested an anti-HIV serology, which was positive. The patient was treated with itraconazole, 200 mg/day, for 120 days, which promoted a complete regression of the lesions. Conclusions Severe and atypical forms of dermatophytosis could lead to a diagnosis of AIDS.

Hereditary epidermolysis bullosa (EB) is a heterogeneous group of rare genetic diseases characterized by fragile skin and/or mucous membrane, and it may be either local or generalized. It is caused by mutations in genes encoding different proteins involved mainly in the structure and function of the dermal-epidermal junction. Nineteen genes have so far been identified. They are classified by level of skin cleavage (from top to bottom) into four groups: EB simplex, junctional EB, dystrophic EB and Kindler syndrome. Clinically suspected diagnosis is confirmed by immunohistochemical examination of a skin biopsy at specialized centres in order to determine the level of cleavage and the deficient protein. This first step may be followed by genetic analysis. The severity of the disease is highly variable, ranging from localized forms with little effect on quality of life to rapidly lethal forms. In generalized severe forms, the extent and chronicity of lesions, as well as mucosal involvement, can lead to systemic complications: malnutrition, pain, joint contractures, chronic inflammation, amyloidosis, cutaneous squamous cell carcinoma. Some specific forms are associated with other cutaneous signs (nail involvement, alopecia, hyperpigmentation, palmoplantar keratoderma) or extracutaneous involvement (muscular dystrophy or pyloric atresia). No curative treatment of EB is available today. EB requires multidisciplinary medical care, nursing, psychological and social management. This is best provided by a specialized network, involving reference centres, centres of expertise and daily caregivers. The goal of treatment is the prevention and treatment of lesions with specific non-adherent dressings and the prevention, detection and treatment of complications. It is essential not to traumatize the skin (bandaging, friction, etc.). Protein, gene or cell replacement therapy, and allogeneic bone marrow, cord blood or pluripotent stem-cell transplantation are currently being assessed. The aim of these French recommendations (national diagnostic and treatment protocol [PNDS]) is to provide healthcare professionals with guidance on the course of EB and on optimal patient management.

T-cell lymphomas (TCLs) account for approximately 15 to 20% of all non-Hodgkin lymphomas in the United States. The most common form of TCL is cutaneous TCL (CTCL), with Sézary syndrome and mycosis fungoides being the most prevalent subtypes. Sézary syndrome is the more aggressive form and often is referred to as a late-stage variant of mycosis fungoides. Clinically, it is characterized by diffuse erythroderma, cutaneous edema, pruritus, nonhealing cutaneous ulcers, and lymphadenopathy. Patients also can present with changes to their nails, hyperpigmentation, alopecia, palmoplantar keratoderma, ectropion, and hepatosplenomegaly. The overall prognosis for patients with Sézary syndrome is poor. The literature regarding oral manifestations of CTCL mostly report those of mycosis fungoides because it is the most common subtype of CTCL. Currently, there are only 2 reports in the scientific literature of intraoral manifestations of Sézary syndrome. This case report describes a patient with Sézary syndrome who presented with rapidly progressing erythematous lesions of the gingiva and multifocal osteonecrosis of the maxilla and mandible. This is the third reported case of an intraoral manifestation of Sézary syndrome and the first reported case of osteonecrosis in the setting of CTCL.

Gap junctions and hemichannels comprised of connexins influence epidermal proliferation and differentiation. Significant advances in our understanding of the functional role of connexins in the skin have been made by studying the diseases caused by connexin mutations. Eleven clinically defined cutaneous disorders with an overlapping spectrum of phenotypes are caused by mutations in five different connexin genes, highlighting that disease presentation must be deciphered with an understanding of how connexin functions are affected. Increasing evidence suggests that the skin diseases produced by connexin mutations result from dominant gains of function. In palmoplantar keratoderma with deafness, the connexin 26 mutations transdominantly alter the function of wild-type connexin 43 and create leaky heteromeric hemichannels. In keratitis-ichthyosis-deafness syndrome, different connexin 26 mutations can either form dominant hemichannels with altered calcium regulation or increased calcium permeability, leading to clinical subtypes of this syndrome. It is only with detailed understanding of these subtle functional differences that we can hope to create successful pathophysiology driven therapies for the connexin skin disorders.

Objectives Mutations in the GJB2 gene encoding connexin 26 (Cx26) are major causes of hereditary deafness. This study aimed to characterize the mutation profiles of the GJB2 gene in a Chinese family with sensorineural hearing loss. Methods A Chinese family that included three individuals with sensorineural hearing loss and palmoplantar keratoderma underwent complete physical examinations, audiological examinations including pure tone audiometry and auditory brainstem response, skin pathological examination, and temporal CT scans. The entire coding region of GJB2, GJB3, GJB6, and the coding exons (exon7 + 8 and 19) of SLC26A4, mitochondrial 12SrRNA, and tRNA Ser (UCN) were sequenced. Structural analysis was performed to detect the effects of mutation on the tertiary structure of Cx26. Results A dominant GJB2 mutation, c.224G>A (p.Arg75Gln, p.R75Q), was detected in the family. No other mutation was identified in GJB2, GJB3, GJB6, or the coding exons (exon7 + 8 and 19) of SLC26A4, mitochondrial 12SrRNA, and tRNA Ser (UCN). Structural analysis revealed that the p.R75Q mutation likely affects the structural stability and permeation properties of the Cx26 gap junction channel. Conclusion Our findings provide further evidence of a correlation between the p.R75Q mutation in Cx26 and a syndromic hearing impairment with palmoplantar keratoderma.

Grainyhead-like 2, encoded by GRHL2, is a member of a highly conserved family of transcription factors that play essential roles during epithelial development. Haploinsufficiency for GRHL2 has been implicated in autosomal-dominant deafness, but mutations have not yet been associated with any skin pathology. We investigated two unrelated Kuwaiti families in which a total of six individuals have had lifelong ectodermal defects. The clinical features comprised nail dystrophy or nail loss, marginal palmoplantar keratoderma, hypodontia, enamel hypoplasia, oral hyperpigmentation, and dysphagia. In addition, three individuals had sensorineural deafness, and three had bronchial asthma. Taken together, the features were consistent with an unusual autosomal-recessive ectodermal dysplasia syndrome. Because of consanguinity in both families, we used whole-exome sequencing to search for novel homozygous DNA variants and found GRHL2 mutations common to both families: affected subjects in one family were homozygous for c.1192T>C (p.Tyr398His) in exon 9, and subjects in the other family were homozygous for c.1445T>A (p.Ile482Lys) in exon 11. Immortalized keratinocytes (p.Ile482Lys) showed altered cell morphology, impaired tight junctions, adhesion defects, and cytoplasmic translocation of GRHL2. Whole-skin transcriptomic analysis (p.Ile482Lys) disclosed changes in genes implicated in networks of cell-cell and cell-matrix adhesion. Our clinical findings of an autosomal-recessive ectodermal dysplasia syndrome provide insight into the role of GRHL2 in skin development, homeostasis, and human disease.

Palmoplantar keratoderma (PPK) is a defect in cornification that is characterized by progressive hyperkeratosis of palms and soles. Many phenotypes are linked with PPK, making exome-based diagnosis increasingly efficient. In this report, we identified tyrosinemia type II on whole-exome sequencing in a 7-year-old Syrian refugee that presented with PPK. Dietary therapy helped improve her overall symptoms.

Introduction Carvajal syndrome is characterized by woolly hair, striated palmoplantar keratoderma and left-sided ventricular cardiomyopathy. It is inherited as an autosomal recessive disorder due to a homozygous mutation in the gene coding for desmoplakin, which truncates the C-terminal of the protein and maps to chromosome 6p24. Signs and symptoms of Carvajal syndrome include: woolly hair that is present from birth, palmoplantar keratoderma that develops after infancy, follicular keratoses on elbows, knees, face, abdomen and lower limbs, clubbing of fingers and rarely mucosal lesions. The desmoplakin (DSP) abnormality can result in arrhythmogenic ventricular cardiomyopathy. Clinical Presentation A 2 month old male of Ecuadorian descent presented with oral ulcerations and poor feeding as reported by his mother. The oral lesions were noted at 2 weeks of age. Bilateral dorsal tongue and palatal erosions with sloughing were noted on oral examination. Skin excoriations were noted at sites of electrocardiogram leads. It was also noted that the child had sparse woolly hair that extended on to the forehead and had a hoarse cry. Intervention and Outcome Biopsies of the anterior dorsal tongue, lingual epiglottis, and duodenal, gastric, esophageal and rectosigmoid mucosa were performed. The tongue and epiglottis surface epithelium consisted of discohesive squamous epithelial cells with interspersed inflammation and bacterial colonies. Esophageal biopsy showed suprabasilar separation from underlying lamina propria. Direct immunofluorescence studies were negative. Whole Exome Sequence Analysis revealed patient was compound heterozygous for the c.7623delT and c.7623delG pathogenic variants in the DSP gene. Conclusion The mucosal lesions of this syndrome can present intraorally, and have a rather unique histopathology characterized by dyskeratosis and discohesion. Patients with this syndrome require regular cardiac evaluations as the cardiac issues are of paramount importance.

The ectodermal dysplasias are a large group of hereditary disorders characterized by alterations of structures of ectodermal origin. Although some syndromes can have specific features, many of them share common clinical characteristics. Two main groups of ectodermal dysplasias can be distinguished. One group is characterized by aplasia or hypoplasia of ectodermal tissues, which fail to develop and differentiate because of a lack of reciprocal signaling between ectoderm and mesoderm, the other has palmoplantar keratoderma as its most striking feature, with additional manifestations when other highly specialized epithelia are also involved. In recent decades, the genes responsible for at least 30 different types of ectodermal dysplasia have been identified, throwing light on the pathogenic mechanisms involved and their correlation with clinical findings.

Keratin 16 (KRT16 in human, Krt16 in mouse), a type I intermediate filament protein, is constitutively expressed in epithelial appendages and is induced in the epidermis upon wounding and other stressors. Mutations altering the coding sequence of KRT16 cause Pachyonychia Congenita (PC), a rare autosomal dominant disorder characterized by hypertrophic nail dystrophy, oral leukokeratosis, and palmoplantar keratoderma (PPK). PPK associated with PC are extremely painful and compromise patient mobility, making them the most debilitating PC symptom. In this study, we show that, although inherited in a recessive fashion, the inactivation of Krt16 in mice consistently causes oral lesions as well as PPK-like hyperkeratotic calluses on Krt16−/− front and hind paws, which severely compromise the animals’ ability to walk. Our findings call into question the view that PC-related PPK arise exclusively as a gain-of-function on the account of dominantly acting mutated keratins, and highlight the key role of modifiers in the clinical heterogeneity of PC symptoms.

Much of the original research on desmosomes and their biochemical components was through analysis of skin and mucous membranes. The identification of desmogleins 1 and 3, desmosomal adhesion glycoproteins, as targets in pemphigus, a fatal autoimmune blistering disease of the skin and mucous membranes, provided the first link between desmosomes, desmogleins, and human diseases. The clinical and histological similarities of staphylococcal scalded skin syndrome or bullous impetigo and pemphigus foliaceus led us to identify desmoglein 1 as the proteolytic target of staphylococcal exfoliative toxins. Genetic analysis of striate palmoplantar keratoderma and hypotrichosis identified their responsible genes as desmogleins 1 and 4, respectively. More recently, these fundamental findings in cutaneous biology were extended beyond the skin. Desmoglein 2, which is expressed earliest among the four isoforms of desmoglein in development and found in all desmosome-bearing epithelial cells, was found to be mutated in arrythmogenic right ventricular cardiomyopathy and has also been identified as a receptor for a subset of adenoviruses that cause respiratory and urinary tract infections. The story of desmoglein research illuminates how dermatological research, originally focused on one skin disease, pemphigus, has contributed to understanding the biology and pathophysiology of many seemingly unrelated tissues and diseases.

Loss-of-function mutation of Jup has been associated with Naxos disease, which is characterized by arrhythmogenic cardiomyopathy and the cutaneous disorder palmoplantar keratoderma. Previously, we have shown that genetic ablation of Jup in cardiomyocytes in mice leads to arrhythmogenic cardiomyopathy similar to Naxos disease in humans. Currently, to determine the pathogenesis of Naxos disease-associated keratoderma, we generated Jup mutant mice by inactivating Jup restrictively in keratinocytes. Jup mutant mice largely recapitulated the clinical features of human palmoplantar keratoderma: overcornification and thickening of the epidermis. Jup mutant mice also suffered skin ulceration and inflammation. Cell apoptosis and proliferation were significantly elevated in Jup mutant epidermis. Ultrastructural analyses revealed the disruption of the assembly of desmosomes and adherens junctions in Jup mutant epidermis. We also demonstrated the compensational increase in β-catenin at Jup mutant cell-cell junctions without altering its signaling activities. Our findings provide important insights for understanding the pathogenesis of human palmoplantar keratoderma.

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Mutations in GJB2, the gene encoding the human gap junction protein connexin26 (Cx26), cause either non-syndromic hearing loss or syndromes affecting both hearing and skin. We have investigated whether dominant Cx26 mutants can interact physically with wild type Cx26. HeLa cells stably expressing wild type Cx26 were transiently transfected to co-express nine individual dominant Cx26 mutants; six associated with non-syndromic hearing loss (W44C, W44S, R143Q, D179N, R184Q, and C202F) and three associated with hearing loss and palmoplantar keratoderma (G59A, R75Q, and R75W). All mutants co-localized and co-immunoprecipitated with wild type Cx26, indicating that they interact physically, likely by forming admixed heteromeric/heterotypic channels. Furthermore, all nine mutants inhibited the transfer of calcein in cells stably expressing Cx26, demonstrating that they each have dominant effects on wild type Cx26. Taken together, these results show that dominant-negative effects of these Cx26 mutants likely contribute to the pathogenesis of hearing loss.

Pachyonychia congenita (PC) is a rare autosomal dominant skin disorder characterized predominantly by nail dystrophy and painful palmoplantar keratoderma. Additional clinical features include oral leukokeratosis, follicular keratosis, and cysts (steatocysts and pilosebaceous cysts). PC is due to heterozygous mutations in one of four keratin genes, namely, KRT6A, KRT6B, KRT16, or KRT17. Here, we report genetic analysis of 90 new families with PC in which we identified mutations in KRT6A, KRT6B, KRT16, or KRT17, thereby confirming their clinical diagnosis. A total of 21 previously unreported and 22 known mutations were found. Approximately half of the kindreds had mutations in KRT6A (52%), 28% had mutations in KRT16, 17% in KRT17, and 3% of families had mutations in KRT6B. Most of the mutations were heterozygous missense or small in-frame insertion/deletion mutations occurring within one of the helix boundary motif regions of the keratin polypeptide. More unusual mutations included heterozygous splice site mutations, nonsense mutations, and a 1-bp insertion mutation, leading to a frameshift and premature termination codon. This study, together with previously reported mutations, identifies mutation hotspot codons that may be useful in the development of personalized medicine for PC.

International audience; Oculo-dento-digital dysplasia (ODDD) is an autosomal dominant disorder with complete penetrance and high intra- and interfamilial phenotypic variability. The key features in this syndrome are microphthalmia, enamel hypoplasia and syndactyly of the 4th-5th fingers. ODDD is caused by mutations in the connexin 43 gene (GJA1). We report here four patients from three families with GJA1 mutations, one of them diagnosed prenatally. The three mutations (c.52T > C/p.Ser18Pro, c.689_690delTA/p.Tyr230CysfsX6, c.442C > G/p.Arg148Gly) have been reported once before. Two patients had white matter hypersignal anomalies, associated in one case with mental retardation, but asymptomatic in the other one, an observation that leads us to discuss systematic neuroradiological imaging for ODDD. One case has optic atrophy, another has hypospadias. The patient carrying a truncating mutation of Cx43 did not have palmoplantar keratoderma, in contradiction with the previously suggested genotype-phenotype correlation between truncating mutation and skin involvement.

Botulinum toxin could represent nowadays a new treatment modality especially for cutaneous conditions in course of which conventional treatments remain unsuccessful. Besides palmar and plantar hyperhidrosis, botulinum toxin has demonstrated efficacy in different conditions associated with hyperhidrosis, such as dyshidrosis, multiple eccrine hidrocystomas, hidradenitis suppurativa, Frey syndrome, but also in different conditions worsened by hyperhidrosis such as Hailey-Hailey disease, Darier disease, inversed psoriasis, aquagenic palmoplantar keratoderma, pachyonychia congenital. Moreover, different cutaneous conditions associated with sensitive disorders and/or neurological involvements could benefit from botulinum toxin, for example anal fissures, leg ulcers, lichen simplex, notalgia paresthetica, vestibulitis. Endly, a case of cutis laxa was described where the patient was improved by cutaneous injections of botulinum toxin.

Summary Background Striate palmoplantar keratoderma (SPPK; OMIM #148700) is a rare autosomal dominant genodermatosis characterized by linear hyperkeratosis on the digits and hyperkeratosis on the palms and soles. SPPK is known to be caused by heterozygous mutations in either the desmoglein 1 ( DSG1 ), desmoplakin ( DSP ), or keratin 1 ( KRT1 ) genes. Objective To define the molecular basis of SPPK in five Pakistani families showing a clear autosomal dominant inheritance pattern of SPPK. Methods Based on previous reports of DSG1 mutations in SPPK, we performed direct sequencing of the DSG1 gene of all five families. Results Mutation analysis resulted in the identification of one recurrent mutation (p.R26X) and four novel mutations (c.Ivs4-2A>G, c.515C>T, c.Ivs9-3C>G, and c.1399delA) in the DSG1 gene. Each mutation is predicted to cause haploinsufficiency of DSG1 protein. Conclusion The results of our study further underscore the significance of the desmoglein gene family in diseases of epidermal integrity.

We report a case of a 15-year-old boy with hyperkeratotic lesions that were linear or striated on the palms and nummular on the soles. He was the only family member known to be affected, suggesting that the condition could be attributed to a de novo mutation or the recessive form of keratoderma palmoplantaris striata, described by Degos as chronic idiopathic acrokeratosis. The lesions did not improve with topical treatments (keratolytic agents, emollients, or corticosteroids) or oral retinoids. We observed that scratching of the affected areas was the main reason for deterioration of the lesions.

Haim-Munk syndrome is an extremely rare autosomal recessive disorder of keratinization characterized clinically by palmoplantar hyperkeratosis, severe early onset periodontitis, onychogryphosis, pes planus, arachnodactyly, and acro-osteolysis. Recently, germline mutations in the lysosomal protease cathepsin C gene have been identified as the underlying genetic defect in Haim-Munk syndrome and in the clinically related disorders, Papillon-Lefèvre syndrome and prepubertal periodontitis.

We report a case of a 15-year-old boy with hyperkeratotic lesions that were linear or striated on the palms and nummular on the soles. He was the only family member known to be affected, suggesting that the condition could be attributed to a de novo mutation or the recessive form of keratoderma palmoplantaris striata, described by Degos as chronic idiopathic acrokeratosis. The lesions did not improve with topical treatments (keratolytic agents, emollients, or corticosteroids) or oral retinoids. We observed that scratching of the affected areas was the main reason for deterioration of the lesions.

Summary Background Pachyonychia congenita (PC) is a rare autosomal dominant keratin disorder, subdivided into two major variants, PC-1 and PC-2. Predominant characteristics include hypertrophic nail dystrophy, focal palmoplantar keratoderma and oral leukokeratosis. Multiple steatocystomas that develop during puberty are a useful feature distinguishing PC-2 from PC-1. At the molecular level it has been shown that mutations in keratin K6a or K16 cause PC-1 whereas those in K6b or K17 lead to PC-2. Objective To identify mutations in 22 families presenting with clinical symptoms of either PC-1/focal non-epidermolytic palmoplantar keratoderma (FNEPPK) or PC-2. Methods Mutation analysis was performed on genomic DNA from PC patients by direct sequencing. Results Here, we report four new missense and five known mutations in K6a; one new deletion and three previously identified missense mutations in K16; plus one known mutation in K17. Conclusion With one exception, all these heterozygous mutations are within the highly conserved helix boundary motif regions at either end of the keratin rod domain. In one sporadic case, a unique mutation in K16 resulting in deletion of 24 bp was found within the central rod domain, in a child with a phenotype predominantly consisting of focal plantar keratoderma. The identification of mutations in cases of PC is prerequisite for future development of gene-specific and/or mutation-specific therapies.

Mutations in the GJB2 gene encoding connexin26 are the major cause of autosomal-recessive or -dominant nonsyndromic congenital sensorineural hearing loss (SNHL) (Kelsell et al., 1997; Kenneson et al., 2002; refer to the connexin-deafness homepage at http://davinci.crg.es/deafness/). In addition, connexin26 mutations have been identified in autosomal-dominant syndromic congenital SNHL with palmoplantar keratoderma (PPK) (Maestrini et al., 1999; Richard et al., 2002, 2004; Brown et al., 2003; van Steensel et al., 2004; Arita et al., 2006). We have encountered a Japanese boy with PPK, knuckle pads and congenital SNHL and GJB2 mutation analysis revealed a novel mutation p.Asn54His.

Summary Background Striate keratodermas (PPKS) are a group of rare autosomal dominant palmoplantar keratodermas, characterized by a thickening of the skin on the palms and soles. PPKS is characterized by hyperkeratosis extending along the length of each finger and on the palm of the hand, as well as by patches of hyperkeratosis on the soles. Objective We report a four-generation Pakistani kindred in which 11 members were affected with PPKS. Methods Based on previous reports of DSG1 mutations in PPKS, we performed direct DNA sequencing analysis. Results Clinically, these patients presented with hyperkeratotic palms and with linear hyperkeratosis on the fingers. Additionally, focal hyperkeratosis was seen on the sole of the toes as well as the ball and heel of the foot. DNA sequencing analysis revealed a heterozygous G-to-T transversion in the 3′ splice acceptor site of intron 11 of the DSG1 gene designated 1688 −1 G > T. We predict that this mutation will lead to the skipping of exon 12 which is out of frame (134 nt), subsequent degradation of the mutant mRNA by non-sense mediated RNA decay, and haploinsufficiency for DSG1. Conclusion We report a novel splice site mutation in the DSG1 gene in PPKS, which further underscores the significance of the desmoglein gene family in diseases of epidermal integrity.

Naxos disease is an autosomal recessively inherited familial syndrome characterized by woolly hair, palmoplantar keratoderma and a cell adhesion cardiomyopathy, especially arrhythmogenic right ventricular dysplasia (ARVD). Carvajal syndrome is a variant of Naxos disease in which curly or woolly hair, biventricular--predominantly left ventricular involvement were seen. Mutations in genes encoding the cell adhesion proteins like plakoglobin and desmoplakin were related with these syndromes. We report a 17-year-old boy and his family findings with curly hair, palmoplantar hyperkeratosis, ARVD and left ventricular involvement. The family was of Arabic origin, and a third-degree consanguinity was reported between the parents. They are from east part of Turkey and there were no relatives from Cyclades Island (Greece). Patient's younger brother had ARVD without cutaneous manifestations of the syndrome and his grand father had mild ARVD, curly hair and palmoplantar hyperkeratosis.

Naegeli-Franceschetti-Jadassohn syndrome (NFJS) and dermatopathia pigmentosa reticularis (DPR) are two closely related autosomal dominant ectodermal dysplasia syndromes that clinically share complete absence of dermatoglyphics (fingerprint lines), a reticulate pattern of skin hyperpigmentation, thickening of the palms and soles (palmoplantar keratoderma), abnormal sweating, and other subtle developmental anomalies of the teeth, hair, and skin. To decipher the molecular basis of these disorders, we studied one family with DPR and four families with NFJS. We initially reassessed linkage of NFJS/DPR to a previously established locus on 17q11.2-q21. Combined multipoint analysis generated a maximal LOD score of 8.3 at marker D17S800 at a recombination fraction of 0. The disease interval was found to harbor 230 genes, including a large cluster of keratin genes. Heterozygous nonsense or frameshift mutations in KRT14 were found to segregate with the disease trait in all five families. In contrast with KRT14 mutations affecting the central alpha -helical rod domain of keratin 14, which are known to cause epidermolysis bullosa simplex, NFJS/DPR-associated mutations were found in a region of the gene encoding the nonhelical head (E1/V1) domain and are predicted to result in very early termination of translation. These data suggest that KRT14 plays an important role during ontogenesis of dermatoglyphics and sweat glands. Among other functions, the N-terminal part of keratin molecules has been shown to confer protection against proapoptotic signals. Ultrastructural examination of patient skin biopsy specimens provided evidence for increased apoptotic activity in the basal cell layer where KRT14 is expressed, suggesting that apoptosis is an important mechanism in the pathogenesis of NFJS/DPR.

A frameshift mutation generated from a dinucleotide deletion (780-781del) in the GJA1 gene encoding Cx43 results in a frameshift yielding 46 aberrant amino acids after residue 259 and a shortened protein of 305 residues compared with the 382 in wild-type Cx43. This frameshift mutant (fs260) causes oculodentodigital dysplasia (ODDD) that includes the added condition of palmoplantar keratoderma. When expressed in a variety of cell lines, the fs260 mutant was typically localized to the endoplasmic reticulum and other intracellular compartments. The fs260 mutant, but not the G138R ODDD-linked Cx43 mutant or a Cx43 mutant truncated at residue 259 (T259), reduced the number of apparent gap junction plaques formed from endogenous Cx43 in normal rat kidney cells or keratinocytes. Interestingly, mutation of a putative FF endoplasmic reticulum retention motif encoded within the 46 aberrant amino acid domain failed to restore efficient assembly of the fs260 mutant into gap junctions. Dual whole cell patch-clamp recording revealed that fs260-expressing N2A cells exerted severely reduced electrical coupling in comparison to wild-type Cx43 or the T259 mutant, whereas single patch capacitance recordings showed that fs260 could also dominantly inhibit the function of wild-type Cx43. Co-expression studies further revealed that the dominant negative effect of fs260 on wild-type Cx43 was dose-dependent, and at a predicted 1:1 expression ratio the fs260 mutant reduced wild-type Cx43-mediated gap junctional conductance by over 60%. These results suggest that the 46 aberrant amino acid residues associated with the frameshift mutant are, at least in part, responsible for the manifestation of palmoplantar keratoderma symptoms.

Keratin gene mutations affecting nonhelical head and tail domains are not usually associated with prominent skin blistering and keratin filament clumping. Instead, they have been associated with several distinct clinical phenotypes, such as epidermolysis bullosa simplex with mottled pigmentation (mutation P25L in the V1 domain of keratin 5), epidermolysis bullosa simplex with migratory circinate erythema (frameshift mutation c1649delG in the V2 domain of keratin 5), striate palmoplantar keratoderma (PPK), and ichthyosis hystrix Curth-Macklin (different frameshift mutations in the V2 domain of keratin 1 (K1)). We have studied a family with severe, diffuse, nonepidermolytic PPK and verrucous hyperkeratotic plaques over the joints and in flexures and identified a new KRT1 gene mutation that is predicted to completely alter the K1 tail domain. In addition, a new K1 size polymorphism has been detected, which is especially prevalent among the African-American population. These results further emphasize the functional importance of the nonhelical tail domain in keratin molecules despite the obvious variability in the number of glycine loop motifs and underscore the broad phenotypic spectrum of disorders due to dominant keratin tail mutations.

Transgrediens et progrediens palmoplantar keratoderma, known as Greither's syndrome, was originally described in 1952 and is characterized by diffuse keratoderma of the palms and soles, extending to the back aspects (transgrediens) and involving the skin over the Achilles' tendon. Patchy hyperkeratosis also develops on the shins, knees, elbows, and sometimes on the skin flexures. We describe two unrelated families affected with Greither's syndrome, in which the same dominant missense mutation gave rise to the amino acid change N188S in K1. The previously reported cases of Greither's syndrome showed phenotypic variability suggestive of different underlying gene defects. Our findings suggest that at least some cases of Greither's syndrome are caused by keratin mutations.