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In the past 2 decades, there has been enormous progress in determining the molecular bases of genodermatoses. This progress has expanded the interface between dermatology and genetics. Integration of clinical and molecular data has simplified disease classification and highlighted relationships among conditions. However, the recent explosion in genetic knowledge has not yet been fully incorporated into clinical dermatology practice or dermatology resident education. This article highlights strategies to overcome barriers and correct practice and educational gaps, enhancing the ability of dermatologists to diagnose, counsel, evaluate, and treat patients and families affected by genodermatoses., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The tissue half-life of proteins largely determines treatment frequency of non-gene-editing-based therapies targeting the cause of genodermatoses. Surprisingly, such knowledge is missing for a vast number of proteins involved in pathologies. The dermal-epidermal junction zone is believed to be a rather static structure, but to our knowledge no detailed analysis of the stability of proteins within this zone has been performed. Here, we addressed the in vivo half-life of collagen type VII using genetic ablation of its expression and therapeutic introduction of exogenous collagen VII in a preclinical model. A similar in vivo stability of collagen VII was observed in the skin, tongue, and esophagus, with a half-life of about 1 month. Collagen VII expressed by intradermally injected mesenchymal stromal cells also exhibited a similar half-life. Our study provides key information needed for the development of protein replacement or cell-based therapies for dystrophic epidermolysis bullosa caused by genetic deficiency of collagen VII. Moreover, by showing what we define as an intermediate half-life of collagen VII, our study challenges the view of the dermal-epidermal junction zone as a static structure with very slow turnover., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Stiff skin syndrome is a rare sclerotic condition that presents during infancy or early childhood. It has an insidious chronic course and may lead to significant co-morbidity and reduced quality of life. Often, affected individuals experience impaired ambulation and immobilization related to joint involvement. Clinically, it may resemble other sclerotic diseases, so histopathological evaluation is necessary to establish a diagnosis. As it is a condition with limited treatment options, prompt diagnosis and early initiation of physical therapy is crucial to prevent joint restriction and maintain quality of life. We describe a case of a 7-year-old with stiff skin syndrome, and review the literature to discuss the clinical presentation, histological findings, and management of this condition.

A 6-month-old female infant presented to our clinic with bilateral eyelid swelling, yellowish-white membranes under both lids, and mucoid ocular discharge. Her aunt had similar ocular problems that were undiagnosed. The conjunctival membranes were excised and histopathological investigation of these membranes showed ligneous conjunctivitis. Further, laboratory examination revealed plasminogen deficiency. A good response was observed to topical fresh frozen plasma (FFP) treatment without systemic therapy, and the membranes did not recur during the treatment. Topical FFP treatment may facilitate rapid rehabilitation and prevent recurrence in patients with ligneous conjunctivitis.

Dowling-Degos disease (DDD) is a rare inherited pigmentary disorder characterised by reticulate pigmentation at flexural sites. No treatment modality has yet been established as a definitive method for the effective elimination of lentigines in DDD. We present a case of a 24-year old woman with DDD treated successfully using intense pulsed light as a novel management strategy., (© 2014 The Australasian College of Dermatologists.)

Scarring alopecia or cicatricial alopecia results from follicular damage that is sufficient to cause the destruction and replacement of pilosebaceous structures by scar tissue. Primary scarring alopecias represent a group of disorders that primarily affect the hair follicles, as opposed to secondary scarring alopecias, which affect the dermis and secondarily cause follicular destruction. Inflammation may predominantly involve lymphocytes or neutrophils. Cicatricial alopecias that mainly involve lymphocytic inflammation include discoid lupus erythematosus, lichen planopilaris, frontal fibrosing alopecia, central centrifugal alopecia, and pseudopelade (Brocq). Cicatricial alopecias that are due to predominantly neutrophilic inflammation include folliculitis decalvans, tufted folliculitis, and dissecting cellulitis of the scalp. Folliculitis keloidalis is a cicatricial alopecia with a mixed inflammatory infiltrate., (© 2015 S. Karger AG, Basel.)

The discovery of methods for reprogramming adult somatic cells into induced pluripotent stem cells (iPSCs) has raised the possibility of producing truly personalized treatment options for numerous diseases. Similar to embryonic stem cells (ESCs), iPSCs can give rise to any cell type in the body and are amenable to genetic correction by homologous recombination. These ESC properties of iPSCs allow for the development of permanent corrective therapies for many currently incurable disorders, including inherited skin diseases, without using embryonic tissues or oocytes. Here, we review recent progress and limitations of iPSC research with a focus on clinical applications of iPSCs and using iPSCs to model human diseases for drug discovery in the field of dermatology., (Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.)

Facial involvement represents a characteristic feature of a wide range of genodermatoses. Specific facial findings often help point to the correct diagnosis, which improves counseling and management. In particular, this can facilitate the identification and treatment of associated extracutaneous disease. The highly visible nature of facial lesions in genodermatoses and facial birthmarks can result in stigmatization and frequently leads to particular concern in patients and their family members. It is therefore critical for dermatologists to be aware of the broad spectrum of facial manifestations in genetic skin disease, especially when these findings have important implications with regard to monitoring and treatment. In this contribution, facial involvement in genodermatoses is divided into five morphologic categories based on the most prominent feature: Papules, scaling, photosensitivity/findings associated with aging (eg, telangiectasias, atrophy, lentigines), blisters/erosions, and birthmarks. Hopefully, this will provide a practical and clinically useful approach to a large and diverse assortment of genetic skin conditions., (Copyright © 2014. Published by Elsevier Inc.)

Skin is an amenable organ for gene replacement and gene editing therapeutics. Its accessibility makes it well-suited for direct topical gene delivery, grafting of genetically corrected cells, and monitoring of possible adverse events. Monogenic recessive disorders with a clinically severe or life-threatening phenotype provide the best candidate diseases for the introduction of a single normal copy of the gene into the target cell, usually keratinocytes. Preclinical studies have shown impressive results in terms of gene correction using both in vivo and ex vivo approaches. The clinical application of gene replacement or genomic editing as potential therapies for inherited skin disorders, however, has been held back by the inadequacy of delivery vectors and concerns from regulatory agencies regarding safety; thus translation to clinical trials has been slow. Over the past 15 years, cell culture and animal models have shown efficient gene correction techniques as preludes to treat inherited skin disorders such as junctional epidermolysis bullosa, dystrophic epidermolysis bullosa, xeroderma pigmentosum, lamellar ichthyosis and Netherton syndrome, but so far only one patient has been treated in a clinical trial. This article reviews the current status of gene therapies for patients with inherited skin diseases and explores future perspectives.

Dissecting cellulitis (DC) also referred to as to as perifolliculitis capitis abscedens et suffodiens (Hoffman) manifests with perifollicular pustules, nodules, abscesses and sinuses that evolve into scarring alopecia. In the U.S., it predominantly occurs in African American men between 20-40 years of age. DC also occurs in other races and women more rarely. DC has been reported worldwide. Older therapies reported effective include: low dose oral zinc, isotretinoin, minocycline, sulfa drugs, tetracycline, prednisone, intralesional triamcinolone, incision and drainage, dapsone, antiandrogens (in women), topical clindamycin, topical isotretinoin, X-ray epilation and ablation, ablative C02 lasers, hair removal lasers (800nm and 694nm), and surgical excision. Newer treatments reported include tumor necrosis factor blockers (TNFB), quinolones, macrolide antibiotics, rifampin, alitretinoin, metronidazole, and high dose zinc sulphate (135-220 mg TID). Isotretinoin seems to provide the best chance at remission, but the number of reports is small, dosing schedules variable, and the long term follow up beyond a year is negligible; treatment failures have been reported. TNFB can succeed when isotretinoin fails, either as monotherapy, or as a bridge to aggressive surgical treatment, but long term data is lacking. Non-medical therapies noted in the last decade include: the 1064 nm laser, ALA-PDT, and modern external beam radiation therapy. Studies that span more than 1 year are lacking. Newer pathologic hair findings include: pigmented casts, black dots, and "3D" yellow dots. Newer associations include: keratitis-ichthyosis-deafness syndrome, Crohn disease and pyoderma gangrenosum. Older associations include arthritis and keratitis. DC is likely a reaction pattern, as is shown by its varied therapeutic successes and failures. The etiology of DC remains enigmatic and DC is distinct from hidradenitis suppurativa, which is shown by their varied responses to therapies and their histologic differences. Like HS, DC likely involves both follicular dysfunction and an aberrant cutaneous immune response to commensal bacteria, such as coagulase negative staphylococci. The incidence of DC is likely under-reported. The literature suggests that now most cases of DC can be treated effectively. However, the lack of clinical studies regarding DC prevents full understanding of the disease and limits the ability to define a consensus treatment algorithm.

Primary localized cutaneous nodular amyloidosis (PLCNA) is a rare disorder that manifests as the cutaneous formation of nodules composed of light-chain amyloid. Although the type of amyloid deposit is similar to primary systemic amyloidosis, there seems to be little, if any, crossover between the 2 diseases. Because reports of PLCNA are sparse, there is no established protocol for treating this disease. This case report presents a 42-year-old man with a visually striking presentation of PLCNA on both feet with some of the lesions possibly being secondary to trauma, a rare phenomenon. The lesions had been present for more than 4 years, and there were no signs or symptoms of systemic amyloidosis. The lesions responded well to a combination of complete curettage followed by CO2; laser ablation. Primary localized cutaneous nodular amyloidosis is rare and difficult to treat, with high rates of recurrence and a concern for progression to systemic amyloidosis. The diagnosis, workup, treatment, and monitoring of PLCNA also are discussed.

We report the case of a 16-year-old boy who presented to our clinic with concomitant hidradenitis suppurativa, inflammatory acne, dissecting cellulitis of the scalp, and pyoderma gangrenosum. Recent reports describe the co-occurrence of pyoderma gangrenosum, acne, and hidradenitis suppurativa. This case further expands the spectrum of concomitant pyoderma gangrenosum and dissecting cellulitis of the scalp., (© 2013 Wiley Periodicals, Inc.)

Hereditary equine regional dermal asthenia is a form of Ehlers-Danlos syndrome, and has an autosomal recessive mode of inheritance. Affected horses are typically born normal and develop lesions within the first 2 years of life. The most common symptoms of the disease include stretchy, loose skin that feels doughy or mushy. More severely affected horses experience spontaneous skin sloughing and extensive lacerations, hematomas, and seromas from minor trauma. Affected horses have a higher than expected incidence of corneal ulcers. DNA testing can normal, establish carrier and affected status. Palliative therapy is available, but no curative treatment exists., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Dowling Degos disease is a rare, reticulate pigmentary disorder with variable phenotypic expression that manifests as hyperpigmented macules and reticulate pigmentary anomaly of the flexures. Many variants of this condition and its overlap with other reticulate pigmentary disorders have been reported in the literature. We present here two cases of DDD with follicular localization, both clinically and histologically. It was associated with ichthyosis vulgaris in one case. Follicular DDD is an uncommon variant of this evolving dermatosis. Our report supports the possible role for disordered follicular keratinisation in its pathogenesis.

New technologies are accelerating the pace at which genetic defects leading to inherited skin disease are elucidated. Translation of these genetic discoveries into new therapies for patients with inherited skin diseases has not been as rapid but the pace is now accelerating. This article summarizes recent findings in genetic skin diseases, the scope of advances being made, the role of new DNA analysis technologies in these discoveries, as well as highlighting some examples of how an understanding of the genetic cause of inherited skin diseases can lead to therapeutic interventions for patients., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Stiff skin syndrome (SSS) is a rare scleroderma-like syndrome characterised by stone hard skin, joint limitation and progressive restriction of chest that may lead to death. We describe the efficacy of haematopoietic autologous stem cell transplantation (HSCT) in a case of SSS secondary to a smouldering myeloma (SM), with severe joint disability, lung interstitial disease and oesophageal dysfunction. The patient was evaluated at 1, 12 and 18 months after HSCT, clinically (joint motility, HAQ and NYHA for dyspnoea) and instrumentally (DLCO, chest HRCT, oesophagus x-ray). After 18 months since HSCT, we observed a high improvement, contemporaneously to SM remission, of HAQ, joint motility, lung (at DLCO and HRCT) and oesophageal abnormalities.

Hereditary blistering skin diseases were described more than hundred years ago, but only the rapid scientific developments in molecular genetics in the last years have revealed the full spectrum of these diseases, delineated disease mechanisms and pointed to novel therapeutic strategies. Not only the classic forms of epidermolysis bullosa, but also new syndromic forms with multiorgan involvement, or skin fragility disorders that manifest with erosive, crusty lesions and pigment anomalies, instead of marked skin blistering belong to the group of hereditary blistering diseases. Understanding the biological functions of skin structures that provide intraepidermal and dermo-epidermal adhesion has furthered development of novel cell- and molecule-based therapies that are currently being tested in preclinical and clinical pilot trial settings.

Nevi represent congenital hamartomatous malformations of various components of the skin. The most common forms are congenital melanocytic nevi (CMN) and nevi of epithelial origin (epidermal and organoid nevi). Large CMN in particular can lead to severe complications and the management of those affected represents a challenge from birth. In contrast to previous assumptions, the risk of malignancy from CMN is considered to be relatively low however, this may be relevantly increased in certain situations. Possible extracutaneous symptoms in cases of central nervous system (CNS) involvement should not be underestimated and early imaging investigations are part of the routine diagnostic procedure. Surgical measures are still very important in the treatment of CMN but the indications must be weighed up for each individual case. Patients often experience marked stigmatization due to disfigurement by their birthmark and this needs to be taken into consideration for their treatment. The most common epithelial nevi are sebaceous nevi. In 2-13 % of cases additional tumors occur within this nevus and early surgical excision is indicated in most cases, not least for aesthetic reasons. If generalized spreading of epidermal nevi occurs, additional investigations are necessary to exclude associated ophthalmological, cardiac or neurological malformations.

The ichthyoses are a heterogeneous group of monogenetically inherited disorders of cornification, and characterized clinically by scaling or hyperkeratosis. Historically, they were classified by clinical features and inheritance patterns. As a result of the recent molecular biological revolution, the ichthyoses are now recognized as comprising many diverse entities. Importantly, identical phenotypes may be caused by mutations in multiple genes, while mutations in a single gene may result in multiple and sometimes widely divergent phenotypes. The considerable complexity of this clinically and genetically heterogeneous group of disorders has prompted the need for a new classification. A classification that uses terminology based on a combination of the clinical and molecular genetic details, for instance loricrin keratoderma, is desirable. In this chapter we will use in principle the nosology adopted recently by an international group of experts at the First Ichthyosis Consensus Conference in Sorèz, France.

Hereditary epidermolysis bullosa is characterized by mechanically induced blistering of the skin and mucous membranes. The causative mechanisms are based on mutations in genes for structural proteins of the epidermis and the dermal-epidermal junction zone. EB is genetically and clinically heterogeneous. Based on the clinical phenotype alone, the diagnosis is difficult in newborns and toddlers, and sometimes even in adults. A precise diagnosis is only possible with laboratory tests like immunofluorescence mapping, electron microscopy and mutation analysis in specialized centers. The treatment is symptomatic and based on the principles of good wound management and - for severe cases - on multidisciplinary care. New data on the pathogenetic mechanisms of epidermolysis bullosa deliver perspectives for development of novel molecular therapies.

Fabry disease is a rare X-linked storage disorder leading to an accumulation of globotriaosylceramides in all cells carrying lysosomes. As the accumulation occurs in most organs, different medical specialties are involved in the diagnostics and therapy of Fabry disease. With this review of the 3 main specialties (cardiology, nephrology, and neurology) and, in addition, the adjacent specialties (ophthalmology and dermatology), we aim to discuss the division-related responsibilities and want to suggest an organ-related additional therapy besides enzyme replacement therapy., (Copyright 2010 Elsevier Inc. All rights reserved.)

In the era of robust genome sequencing, a working understanding of genetics has become important for the clinician. For the dermatologist, understanding the flow of genetic information from genotype to phenotype can aid in the delivery of effective patient care. In this article, we will review concepts in genetics and the human genome and how they contribute to clinical dermatology., (Copyright 2010 Elsevier Inc. All rights reserved.)

Extracellular deposition of altered autologous protein (amyloid protein) within the dermis is the hallmark of cutaneous amyloidoses and systemic amyloidoses with cutaneous involvement. Amyloidoses may be acquired or hereditary in nature and subclassification differentiates between primary amyloidosis (no obvious predisposing disease) and secondary amyloidosis (specific underlying disease). More than 26 different proteins and peptides have been identified as amyloid precursors and these proteins are used to subclassify this heterogeneous group of diseases. The amyloid proteins show an anti-parallel beta-sheet conformation and form non-branching linear filaments of variable lengths and diameters of approximately 7.5 to 10 nm. However, the exact etiopathogenesis of amyloid formation still remains unclear. Depending on histoanatomical distribution and amount, amyloid may cause progressive and life-threatening organ dysfunction. Clinical presentation, histology, electron microscopy, and biochemical-immunological differentiation represent decisive tools for an accurate diagnosis.

The porphyrias are clinically and genetically heterogeneous metabolic disorders resulting from a predominantly hereditary dysfunction of specific enzymes involved in heme biosynthesis. Today, the clinical, biochemical, and genetic characteristics of this fascinating group of diseases are well established. Recently, different in vitro and animal models have facilitated the investigation of etiopathologic mechanisms in the different types of porphyria and the development of causal treatment strategies such as pathway interference, enzyme replacement, and gene therapy. The continuous progress in basic science has made an invaluable contribution to the rapid translation of discoveries made in the laboratory into new diagnostics and therapeutics in the near future., (2010 S. Karger AG, Basel.)

A major issue in long-term gene therapy is host immune responses to therapeutic cells when transgene encodes a potential antigen. The nature of these responses depends on several factors including the type of cell and tissue expressing the transgene. Keratinocytes and fibroblasts, which are known to display distinct immunogenic profiles, are both potential targets for transgene expression in cutaneous gene therapy. However, whether there is an immunological advantage in targeting one cell type over the other is not known. To study the effect of cell type on transgene-specific host responses independent of antigen levels or methods of gene transfer and transplantation, we used a skin transplantation model in which transgene expression can be targeted transgene to either keratinocytes or fibroblasts. Although targeting an antigen to either cell type resulted in the induction of immune responses, these responses differed significantly. Transgenic keratinocytes were rejected acutely by a dominant Th2 response, while in the majority of grafted animals transgenic fibroblasts failed to induce acute rejection despite the induction of Th1 type inflammation in the graft. In a small number of mice, transgenic fibroblasts persisted for at least 20 weeks despite elicitation of antigen-specific responses. Therefore, fibroblasts may be an immunologically preferred target over keratinocytes for cutaneous gene therapy.

Tremendous progress has been made over the past two decades in understanding the molecular genetics of heritable skin diseases. The paradigm for such conditions is epidermolysis bullosa (EB), which comprises a group of heritable blistering disorders caused by mutations in ten genes expressed in the cutaneous basement membrane zone and has high morbidity and mortality. Identification of distinct mutations has improved the diagnosis and subclassification of EB, leading to improvements in disease prognosis, and has provided a basis for prenatal and pre-implantation genetic diagnosis for this disorder. Nevertheless, there is no cure or effective treatment for EB. Here, we review recent exciting developments in the areas of molecular therapies, including gene therapy, protein replacement therapy and bone-marrow-derived stem cell transfer, as potential new avenues to treat EB and other currently intractable heritable skin diseases.

Epidermolysis bullosa, a group of blistering disorders, serves as the paradigm of the tremendous progress made in understanding the molecular genetics of heritable skin diseases. Mutations in 10 distinct genes have been disclosed in the classic forms of epidermolysis bullosa, and the level of expression of the mutated genes within the cutaneous basement membrane zone, the types and combinations of mutations and their consequences at the mRNA and protein levels, when placed in the context of the individual's genetic background and exposure to environmental trauma, all determine the subtype and the phenotypic severity in each case. The translational implications of mutation analysis include improved diagnosis and subclassification, refined genetic counseling of families at risk, and development of DNA-based pre natal and preimplantation genetic diagnosis. The prospects of molecular therapies for epidermolysis bullosa include further development of strategies for gene therapy, protein replacement therapy and cell-based therapies, including stem cell therapy and bone marrow transfer. Collectively, advances in the molecular genetics of heritable skin diseases clearly emphasize the value of basic research for improved diagnostics and patient care for genetic skin diseases.

The field of science and medicine has experienced a flood of data and technology associated with the human genome project. Over 10,000 human diseases have been genetically defined, but little progress has been made with respect to the clinical application of this knowledge. A notable exception to this exists for pachyonychia congenita (PC), a rare, dominant-negative keratin disorder. The establishment of a non-profit organization, PC Project, has led to an unprecedented coalescence of patients, scientists, and physicians with a unified vision of developing novel therapeutics for PC. Utilizing the technological by-products of the human genome project, such as RNA interference (RNAi) and quantitative RT-PCR (qRT-PCR), physicians and scientists have collaborated to create a candidate siRNA therapeutic that selectively inhibits a mutant allele of KRT6A, the most commonly affected PC keratin. In vitro investigation of this siRNA demonstrates potent inhibition of the mutant allele and reversal of the cellular aggregation phenotype. In parallel, an allele-specific quantitative real-time RT-PCR assay has been developed and validated on patient callus samples in preparation for clinical trials. If clinical efficacy is ultimately demonstrated, this "first-in-skin" siRNA may herald a paradigm shift in the treatment of dominant-negative genetic disorders.

Background: Kindler syndrome (KS) is a rare genodermatosis characterized by four major features (acral blisters, photosensitivity, poikiloderma, and cutaneous atrophy) and many associated findings. The diagnosis of KS includes clinical features, ultrastructural findings, and, recently, immunostaining and genetic studies. Varying degrees of severity of the syndrome have been described., Methods: Five patients with clinical features consistent with KS were included in this study. All patients were subjected to histopathologic and ultrastructural studies., Results: Cases 1 and 2 presented with severe major features, severe mucosal involvement, and many other associated findings. Case 3 presented with severe major features, but mild and limited mucosal involvement and other associated findings. Cases 4 and 5 showed mild major features and few other findings. Histopathology revealed nonspecific poikiloderma. Marked thickening of the lamina densa and splitting of the lamina lucida were the main ultrastructural findings., Conclusion: KS may be classified into mild, moderate, and severe according to the severity of the major features and mucosal involvement. Because histopathologic and ultrastructural findings are not pathognomonic, clinical features remain the mainstay for the diagnosis of KS, and the need for immunostaining with kindlin antibody and genetic studies may be restricted to early cases with incomplete features.

Over the past decade, many approaches to transferring genes into the skin have been investigated. However, most such approaches have been specifically aimed against genodermatosis, and have not produced sufficient results. The goal of such research is to develop a method in which genes are transferred easily, efficiently and stably into keratinocytes, especially into keratinocyte stem cells, and in which the transgene expression persists without a reaction from the host immune response. Although accidental development of cancer has occurred in trials of gene therapy for X-linked severe combined immunodeficiency (X-SCID), resulting in slowing of the progress of this research, the lessons of these setbacks have been applied to further research. Moreover, combined with the techniques acquired from tissue engineering, recent developments in our knowledge about stem cells will lead to new treatments for genodermatoses. The present review summarizes the methods by which therapeutic genes can be transferred into keratinocytes, with discussion of how gene transfer efficiency can be improved, with particular emphasis on disruption of the skin barrier function. It concludes with discussion of the challenges and prospects of keratinocyte gene therapy, in terms of achieving efficient and long-lasting therapeutic effects.

For gene therapy purposes, the skin is an attractive organ to target for systemic delivery of therapeutic proteins to treat systemic diseases, skin diseases, or skin cancer. To achieve long-term stable expression of a therapeutic gene in keratinocytes (KC), we have developed an approach using a bicistronic retroviral vector expressing the desired therapeutic gene linked to a selectable marker (multidrug resistant gene, MDR) that is then introduced into KC and fibroblasts (FB) to create genetically modified human skin equivalent (HSE). After grafting the HSE onto immunocompromised mice, topical colchicine treatment is used to select and enrich for genetically modified keratinocyte stem cells (KSC) that express MDR and are resistant to colchicine's antimitotic effects. Both the apparatus for topical colchicine delivery and the colchicine doses have been optimized for application to human skin. This approach can be validated by systemic delivery of therapeutic factors such as erythropoietin and the antihypertensive atrial natriuretic peptide.

Possibilities of using the skin for somatic gene therapy have been investigated for more than 20 years. Strategies have included both direct gene transfer into the skin and indirect gene transfer utilizing cultured cells as an intermediate step for gene manipulation. Viral as well as nonviral vectors have been used, and both gene addition and gene editing have been performed. Although cutaneous gene therapy has now begun translating into clinical medicine (as seen by the first clinical gene therapy project of an inherited skin disorder) further developments are still required.

Epidermolysis bullosa (EB) and associated skin-fragility syndromes are a group of inherited skin diseases characterised by trauma-induced blistering of the skin and mucous membranes. Mutations in at least 14 distinct genes encoding molecular components of the epidermis or the dermal-epidermal junction (DEJ) can cause blistering skin diseases that differ by clinical presentation and severity of the symptoms. Despite great advances in discerning the genetic basis of this group of diseases, the molecular pathways leading to symptoms are not yet fully understood. Unravelling these pathways by molecular analysis of the structure and in vitro assessment of functional properties of the human proteins involved, combined with genetic models in lower organisms, should pave the way for specific cures for inherited skin fragility.