The prevalence of epidermolysis bullosa in Scotland

Allele-Specific Inactivation of an Autosomal Dominant Epidermolysis Bullosa Simplex Mutation Using CRISPR-Cas9

Epidermolysis bullosa simplex (EBS) is a rare mechanobullous disease caused by dominant-negative mutations in either keratin 5 (KRT5) or keratin 14 (KRT14) genes. Until now, there is no cure for EBS and the care is primarily palliative. The discovery of the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 system raised hope for the treatment of EBS and many other autosomal dominant diseases by mutant allele-specific gene disruption. In this study, we aim to disrupt the mutant allele for the heterozygous EBS pathogenic variation c.449T>C (p.Leu150Pro) within KRT5. This mutation generates, naturally, a novel protospacer-adjacent motif for the endonuclease Streptococcus pyogenes Cas9. Thus, we designed a single-guide RNA that guides the Cas9 to introduce a DNA cleavage of the mutant allele in patient's keratinocytes. Then, transfected cells were single-cell cloned and analyzed by deep sequencing. The expression of KRT5 and KRT14 was quantified, and the keratin intermediate filament stability was assessed. Results showed successful stringent mutant allele-specific knockout. An absence of synthesis of mutant transcript was further confirmed indicating permanent mutant allele-specific inactivation. Edited EBS patient keratinocytes produced a lower amount of K5 and K14 proteins compared with nonedited EBS cells, and no disturbance of cellular properties was observed.

Anesthetic Management of Adults With Epidermolysis Bullosa

Epidermolysis bullosa (EB) is a group of rare, inherited diseases characterized by skin fragility and multiorgan system involvement that presents many anesthetic challenges. Although the literature regarding anesthetic management focuses primarily on the pediatric population, as life expectancy improves, adult patients with EB are more frequently undergoing anesthesia in nonpediatric hospital settings. Safe anesthetic management of adult patients with EB requires familiarity with the complex and heterogeneous nature of this disease, especially with regard to complications that may worsen during adulthood. General, neuraxial, and regional anesthetics have all been used safely in patients with EB. A thorough preoperative evaluation is essential. Preoperative testing should be guided by EB subtype, clinical manifestations, and extracutaneous complications. Advanced planning and multidisciplinary coordination are necessary with regard to timing and operative plan. Meticulous preparation of the operating room and education of all perioperative staff members is critical. Intraoperatively, utmost care must be taken to avoid all adhesives, shear forces, and friction to the skin and mucosa. Special precautions must be taken with patient positioning, and standard anesthesia monitors must be modified. Airway management is often difficult, and progressive airway deterioration can occur in adults with EB over time. A smooth induction, emergence, and postoperative course are necessary to minimize blister formation from excess patient movement. With careful planning, preparation, and precautions, adult patients with EB can safely undergo anesthesia.

The quality of life in epidermolysis bullosa (EB-QoL) questionnaire: Translation, cultural adaptation, and validation into the Farsi language

Background

Defining the quality of life in the patients with epidermolysis bullosa (EB) is important in patient care and management. Evaluation of quality of life requires a valid and reliable scale. The Quality of Life in Epidermolysis Bullosa (EB-QoL) questionnaire, which is an English 17-item questionnaire, has emerged as a useful tool for assessing the quality of life in the patients with EB.

Objective

This study aimed to evaluate the psychometric properties of the Farsi version of the EB-QoL questionnaire among a group of Iranian patients with EB.

Methods

The Farsi version of the EB-QoL questionnaire was finalized after translation and back-translation. From the 100 patients with EB invited to participate in the study, 83 completed the questionnaire (response rate: 83%). Subsequently, the content validity and construct validity of the questionnaire were assessed. The reliability of the questionnaire was assessed with Cronbach's alpha. Moreover, the correlation between EB-QoL scores and EB severity scores (based on the Birmingham Epidermolysis bullosa severity score scale) was evaluated.

Results

A total of 83 patients (40 male and 43 female) with a median age of 15 years (interquartile range, 9–24 years) and an age range between 3 and 43 years were enrolled in this study. Mean ± standard deviation scores from the EB-QoL questionnaire were 43.7 ± 9.9. The translated EB-QoL questionnaire showed a high internal consistency (Cronbach alpha = 0.90) and adequate item-total correlation. Also, there was a significant correlation between EB-QoL and EB severity scores (r = 0.39; p < .001).

Conclusion

The Farsi version of EB-QoL questionnaire has acceptable validity and reliability. Thus, the questionnaire can be used for future studies to assess the quality of life among Iranian patients with EB.

Epidermolysis bullosa

Epidermolysis bullosa (EB) is an inherited, heterogeneous group of rare genetic dermatoses characterized by mucocutaneous fragility and blister formation, inducible by often minimal trauma. A broad phenotypic spectrum has been described, with potentially severe extracutaneous manifestations, morbidity and mortality. Over 30 subtypes are recognized, grouped into four major categories, based predominantly on the plane of cleavage within the skin and reflecting the underlying molecular abnormality: EB simplex, junctional EB, dystrophic EB and Kindler EB. The study of EB has led to seminal advances in our understanding of cutaneous biology. To date, pathogenetic mutations in 16 distinct genes have been implicated in EB, encoding proteins influencing cellular integrity and adhesion. Precise diagnosis is reliant on correlating clinical, electron microscopic and immunohistological features with mutational analyses. In the absence of curative treatment, multidisciplinary care is targeted towards minimizing the risk of blister formation, wound care, symptom relief and specific complications, the most feared of which - and also the leading cause of mortality - is squamous cell carcinoma. Preclinical advances in cell-based, protein replacement and gene therapies are paving the way for clinical successes with gene correction, raising hopes amongst patients and clinicians worldwide.

Epidermolysis Bullosa-Associated Squamous Cell Carcinoma: From Pathogenesis to Therapeutic Perspectives

Epidermolysis bullosa (EB) is a heterogeneous group of inherited skin disorders determined by mutations in genes encoding for structural components of the cutaneous basement membrane zone. Disease hallmarks are skin fragility and unremitting blistering. The most disabling EB (sub)types show defective wound healing, fibrosis and inflammation at lesional skin. These features expose patients to serious disease complications, including the development of cutaneous squamous cell carcinomas (SCCs). Almost all subjects affected with the severe recessive dystrophic EB (RDEB) subtype suffer from early and extremely aggressive SCCs (RDEB-SCC), which represent the first cause of death in these patients. The genetic determinants of RDEB-SCC do not exhaustively explain its unique behavior as compared to low-risk, ultraviolet-induced SCCs in the general population. On the other hand, a growing body of evidence points to the key role of tumor microenvironment in initiation, progression and spreading of RDEB-SCC, as well as of other, less-investigated, EB-related SCCs (EB-SCCs). Here, we discuss the recent advances in understanding the complex series of molecular events (i.e., fibrotic, inflammatory, and immune processes) contributing to SCC development in EB patients, cross-compare tumor features in the different EB subtypes and report the most promising therapeutic approaches to counteract or delay EB-SCCs.

Identification of tissue damage, extracellular matrix remodeling and bacterial challenge as common mechanisms associated with high-risk cutaneous squamous cell carcinomas

In this study we used a genetic extracellular matrix (ECM) disease to identify mechanisms associated with aggressive behavior of cutaneous squamous cell carcinoma (cSCC). cSCC is one of the most common malignancies and usually has a good prognosis. However, some cSCCs recur or metastasize and cause significant morbidity and mortality. Known factors that are associated with aggressiveness of cSCCs include tumor grading, size, localization and microinvasive behavior. To investigate molecular mechanisms that influence biologic behavior we used global proteomic and histologic analyses of formalin-fixed paraffin-embedded tissue of primary human cSCCs. We compared three groups: non-recurring, non-metastasizing low-risk sporadic cSCCs; metastasizing sporadic cSCCs; and cSCCs from patients with recessive dystrophic epidermolysis bullosa (RDEB). RDEB is a genetic skin blistering and ECM disease caused by collagen VII deficiency. Patients commonly suffer from high-risk early onset cSCCs that frequently metastasize. The results indicate that different processes are associated with formation of RDEB cSCCs compared to sporadic cSCCs. Sporadic cSCCs show signs of UV damage, whereas RDEB cSCCs have higher mutational rates and display tissue damage, inflammation and subsequent remodeling of the dermal ECM as tumor initiating factors. Interestingly the two high-risk groups - high-risk metastasizing sporadic cSCCs and RDEB cSCCs - are both associated with tissue damage and ECM remodeling in gene-ontology enrichment and Search Tool for the Retrieval of Interacting Genes/Proteins analyses. In situ histologic analyses validate these results. The high-risk cSCCs also show signatures of enhanced bacterial challenge. Histologic analyses confirm correlation of bacterial colonization with worse prognosis. Collectively, this unbiased study - performed directly on human patient material - reveals that common microenvironmental alterations linked to ECM remodeling and increased bacterial challenges are denominators of high-risk cSCCs. The proteins identified here could serve as potential diagnostic markers and therapeutic targets in high-risk cSCCs.

Higher Dental Caries Prevalence and Its Association with Dietary Habits and Physical Limitation in Epidermolysis Bullosa Patients: A Case Control Study

AIM

Epidermolysis bullosa (EB) represents a highly rare subgroup of skin diseases that affects skin and mucous membrane. The aim of the present study was to assess caries prevalence and its associated factors in EB subjects. Salivary status was also assessed.

MATERIALS AND METHODS

Ten subjects with EB who were under supervision were selected (cases) and matched by age and gender with unaffected individuals (controls). Dental caries were recorded using the World Health Organization (WHO) criteria. Oral hygiene and dietary habits were investigated by clinical examination and questionnaires. Both nonstimulated and stimulated saliva were collected and salivary pH, buffering capacity and mouth opening were evaluated.

RESULTS

The results showed that the median decay-missing-filled teeth was significantly higher (p = 0.0094) in EB cases 5 (3.9-20.3) than in controls 3 (2-3.25). The groups also differed when food consistency was analyzed. Individuals with EB have a higher intake of soft food. In addition, the median mouth-opening values from cases (0.84-2.84 cm) and controls (4.3-4.9 cm) have shown to be statistically different (p = 0.007). Considering the salivary parameters, none of them showed significant differences among groups.

CONCLUSION

Epidermolysis bullosa subjects present higher caries scores and might be related to their physical condition and dietary habits.

CLINICAL SIGNIFICANCE

There is a lack of information about oral status in EB subjects. Hence, our findings add useful information regarding the relationship between caries prevalence and associated risk factors in EB subjects.

Prevalence of hereditary epidermolysis bullosa in the Russian Federation

Goal. To study the prevalence of hereditary epidermolysis bullosa (HEB) in the Russian Federation. Materials and methods. The data on the number of HEB patients by subjects of the Russian Federation as well as their age and disease type were obtained based on questionnaires. The questionnaires were sent to dermatovenerology healthcare institutions from 85 subjects of the Russian Federation. The HEB prevalence rates in the subjects of the Russian Federation were calculated as the ratio of the number of HEB patients in the subject of the Russian Federation to the population size in the subject per million residents. Results. Information about 438 HEB patients (210 female and 228 male) aged 0-66 was collected in 70 subjects of the Russian Federation as of January 1, 2015. The disease type was specified for 139 patients (86 patients with common HEB, 50 patients with dystrophic HEB and 3 patients with the borderline form of HEB). No details about the disease type were provided for 299 patients (68.26%). The HEB prevalence rate in the subjects of the Russian Federation varies from 0 to 19.73 cases per million residents. Conclusion. These data on the HEB prevalence rate in 70 subjects of the Russian Federation are comparable to the data specified in literature sources providing information on the HEB prevalence rate in some foreign states. The data represent the first step to the development of clinical recommendations concerning HEB management and establishment of a register of in the Russian Federation.

Inherited epidermolysis bullosa: an update and suggested dental care considerations

BACKGROUND

Epidermolysis bullosa (EB) is a skin disease characterized by epithelial fragility that leads to blistering and erosion of the skin and mucosae. The authors conducted a literature review to provide an update on oral manifestations and dental care of patients with EB. Literature Search. The authors reviewed the dental literature on EB in relation to clinical findings and provision of dental care. They searched textbooks and three databases: MEDLINE, Cochrane Library and Embase. The authors did not impose any date or publication status restrictions. They searched all databases up to August 2010.

RESULTS

The literature review revealed that four major groups and 32 subtypes of EB can be distinguished on the basis of the ultrastructural characteristics of skin cleavage, genetic mode of transmission and clinical phenotype. Oral manifestations differ in frequency and severity according to the disease subtype, but the most common are bullae, which leave painful ulcers on rupture, followed by scarring and tissue contraction. Although good oral health status is essential to maintaining oral function, dental treatment can induce new lesions and be hindered by the sequelae of existing lesions.

CLINICAL IMPLICATIONS

Dental treatment in patients with EB requires a multidisciplinary approach. Dental procedures must be minimally traumatic, and the effectiveness of treatment is determined mainly by the patient's general health, cooperation in the dental office and at home, oral hygiene and diet.

Two novel recessive mutations in KRT14 identified in a cohort of 21 Spanish families with epidermolysis bullosa simplex

BACKGROUND

Basal epidermolysis bullosa simplex (EBS) is a group of blistering genodermatoses mostly caused by mutations in the keratin genes, KRT5 and KRT14. Recessive mutations represent about 5% of all EBS mutations, being common and specific in populations with high consanguinity, where affected patients show severe phenotypes.

OBJECTIVES

To accomplish the first mutational analysis in patients of Spanish origin with EBS and to delineate a comprehensive genotype-phenotype correlation.

METHODS

Twenty-one EBS families were analysed. Immunofluorescence mapping at the dermoepidermal junction level was performed on skin biopsies from patients. Mutation screening of the entire coding sequences of KRT5 and KRT14 in genomic DNA was assessed by polymerase chain reaction and direct sequencing.

RESULTS

KRT5 or KRT14 causative mutations were identified in 18 of the 21 EBS families. A total of 14 different mutations were disclosed, of which 12 were dominant missense mutations and two truncating recessive mutations. Five of the 14 mutations were novel including three dominant in KRT5 (p.V186E, p.T321P and p.A428T) and two recessive in KRT14 (p.K116X and p.K250RfsX8). The two patients with EBS carrying homozygous recessive mutations were affected by severe phenotypes and belonged to consanguineous families. All five families with the EBS Dowling-Meara subtype carried recurrent mutations affecting the highly conserved ends of the α-helical rod domain of K5 and K14. The seven mutations associated with the localized EBS subtype were widely distributed along the KRT5 and KRT14 genes. Two families with mottled pigmentation carried the P25L mutation in KRT5, commonly associated with this subtype.

CONCLUSIONS

This study further confirms the genotype-phenotype correlation established for EBS in other ethnic groups, and is the first in a Mediterranean country (excluding Israel). This study adds two novel recessive mutations to the worldwide record to date, which includes a total of 14 mutations. As in previous reports, the recessive mutations resulted in a lack of keratin K14, giving rise to a generalized and severe presentation.

The international dystrophic epidermolysis bullosa patient registry: an online database of dystrophic epidermolysis bullosa patients and their COL7A1 mutations

Dystrophic epidermolysis bullosa (DEB) is a heritable blistering disorder that can be inherited autosomal dominantly (DDEB) or recessively (RDEB) and covers a group of several distinctive phenotypes. A large number of unique COL7A1 mutations have been shown to underlie DEB. Although general genotype-phenotype correlation rules have emerged, many exceptions to these rules exist, compromising disease diagnosing and genetic counseling. We therefore constructed the International DEB Patient Registry (http://www.deb-central.org), aimed at worldwide collection and sharing of phenotypic and genotypic information on DEB. As of May 2011, this MOLGENIS-based registry contains detailed information on 508 published and 71 unpublished patients and their 388 unique COL7A1 mutations, and includes all combinations of mutations. The current registry RDEB versus DDEB ratio of 4:1, if compared to prevalence figures, suggests underreporting of DDEB in the literature. Thirty-eight percent of mutations stored introduce a premature termination codon (PTC) and 43% an amino acid change. Submission wizards allow users to quickly and easily share novel information. This registry will be of great help in disease diagnosing and genetic counseling and will lead to novel insights, especially in the rare phenotypes of which there is often lack of understanding. Altogether, this registry will greatly benefit the DEB patients.

The psychosocial impact of epidermolysis bullosa

Epidermolysis bullosa (EB) is a disease in which the skin blisters in response to minimal friction, causing painful wounds. Despite the potentially severe nature of epidermolysis bullosa, research on the psychosocial issues is scarce. The aims of the study were to explore the psychosocial impact of epidermolysis bullosa on affected adults and to identify associated support needs. We collected data using semistructured interviews and employed inductive thematic analysis to organize and analyze them. Three main themes—beliefs about containing the impact of EB, understandings of the disease, and the disabling impact of EB—describe the ways in which living with EB influences the daily lives of participants at intraindividual, interindividual, and sociocultural levels. The associated support needs ranged in type and intensity, from a preference for brief, skills-based interventions and the facilitation of peer support through to longer-term specialist psychological support. The results highlight how the particular combination of the rarity of the disease, its lifelong and hereditary nature, and its disfiguring impact on the skin differentiate epidermolysis bullosa from other chronic conditions.

Mutations in KRT5 and KRT14 cause epidermolysis bullosa simplex in 75% of the patients

BACKGROUND

Epidermolysis bullosa simplex (EBS) is a mechanobullous genodermatosis that may be caused by mutations in the genes KRT5 and KRT14 encoding the basal epidermal keratins 5 (K5) and 14 (K14). Three main clinical subtypes of EBS exist, differing in onset, distribution and severity of skin blistering. Previous reports of KRT5 and KRT14 mutations suggest a correlation between the location of the mutation and the severity of the associated EBS phenotype.

OBJECTIVES

The prevalence of KRT5/KRT14 mutations and the genotype-phenotype correlation in the largest tissue-confirmed EBS population is investigated.

METHODS

KRT5 and KRT14 genomic DNA and cDNA sequences of 76 clinically well-defined unrelated EBS probands were amplified and then subjected to direct sequencing and product length analysis. Immunofluorescence microscopy on patients' skin biopsies with antibodies against K5 and K14 was performed to study protein expression.

RESULTS

In 57 of 76 (75%) probands 41 different KRT5 and KRT14 mutations were identified, of which 12 were novel. Mutations affecting the highly conserved helix boundary motifs of the rod domains of K5 and K14, and the K14 helix initiation motif in particular, were associated with the severest, EBS Dowling-Meara, phenotype. In 21 EBS probands (37%) the mutation was de novo. In 19 probands (25%) KRT5 or KRT14 mutations were excluded.

CONCLUSIONS

The phenotype-genotype correlation observed in this large EBS population underscores the importance of helix boundary motifs for keratin assembly. Only three-quarters of biopsy-confirmed EBS probands have KRT5 or KRT14 mutations, indicating genetic heterogeneity in EBS. Alternative gene candidates are discussed.

Factors affecting quality of life in epidermolysis bullosa

Epidermolysis bullosa is a rare group of inherited disorders that manifests as blistering or erosion of the skin in response to little or no apparent trauma. Patients suffer from long-term physical, social and economic consequences. Despite the fact that quality of life assessment has rapidly become a significant outcome variable in dermatology research, only a few studies regarding epidermolysis bullosa patients are available. This paper reviews studies evaluating the effect of epidermolysis bullosa on quality of life in patients and caregivers in order to assess which factors can best describe their health-related quality of life. Currently, considerable deficits prevail in both the diagnosis and treatment of rare skin diseases. Moreover, the psychological and social morbidities very easily evade the eyes of clinicians. Comparison of the impact of epidermolysis bullosa with that of other conditions is clearly valuable for making public policy decisions. This review indicates the need for more rigorous exploration of the impact of such diseases to further guide treatment and to monitor quality of care.

Inherited epidermolysis bullosa

Inherited epidermolysis bullosa (EB) encompasses a number of disorders characterized by recurrent blister formation as the result of structural fragility within the skin and selected other tissues. All types and subtypes of EB are rare; the overall incidence and prevalence of the disease within the United States is approximately 19 per one million live births and 8 per one million population, respectively. Clinical manifestations range widely, from localized blistering of the hands and feet to generalized blistering of the skin and oral cavity, and injury to many internal organs. Each EB subtype is known to arise from mutations within the genes encoding for several different proteins, each of which is intimately involved in the maintenance of keratinocyte structural stability or adhesion of the keratinocyte to the underlying dermis. EB is best diagnosed and subclassified by the collective findings obtained via detailed personal and family history, in concert with the results of immunofluorescence antigenic mapping, transmission electron microscopy, and in some cases, by DNA analysis. Optimal patient management requires a multidisciplinary approach, and revolves around the protection of susceptible tissues against trauma, use of sophisticated wound care dressings, aggressive nutritional support, and early medical or surgical interventions to correct whenever possible the extracutaneous complications. Prognosis varies considerably and is based on both EB subtype and the overall health of the patient.

A systematic review of randomized controlled trials of treatments for inherited forms of epidermolysis bullosa

BACKGROUND

Many interventions have been described for inherited epidermolysis bullosa (EB), but it is unclear which are beneficial.

AIMS

A systematic review of randomized controlled trials (RCTs) was performed to inform practice and highlight research gaps.

METHODS

The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and the Cochrane Skin Group specialist library, from inception until 1 April 2007, were searched. Primary outcomes were healing of lesions or prevention of new lesions. Trials were assessed for quality of reporting and data were extracted.

RESULTS

Five randomized double-blind placebo-controlled crossover studies were identified (n = 102). Two studies assessed oral tetracyclines in EB simplex (EBS). In one study (n = 12), 4/6 patients improved and 2/6 deteriorated on a dose of 1500 mg of tetracycline daily; only two patients completed the study. In the second study (n = 21), 6/18 and 7/18 improved on oxytetracycline 1 g and placebo, respectively. Two RCTs assessed topical interventions for EBS: aluminium chloride hexahydrate solution 20% (n = 23) and bufexamac cream 5% (n = 8). Neither showed a benefit over placebo. One RCT of 36 patients with recessive dystrophic EB compared phenytoin with placebo and failed to show any difference in mean lesion counts (difference = 0, 95% CI -11 to 4).

CONCLUSIONS

There is no reliable trial evidence for interventions in inherited EB. In future, it may be that gene treatment becomes the best treatment approach for these diseases.

Anaesthetic management of two different modes of delivery in patients with dystrophic epidermolysis bullosa

Dystrophic epidermolysis bullosa is an inherited severe bullous condition characterised by extreme skin fragility and blistering in response to minor trauma. We present two obstetric cases with recessive dystrophic epidermolysis bullosa, one who underwent elective caesarean section, the other who delivered vaginally. The key points in the anaesthetic management of the obstetric patient with dystrophic epidermolysis bullosa include multidisciplinary preassessment, airway management strategies and the role of regional anaesthesia.

Epidermolysis Bullosa Simplex in Scotland Caused by a Spectrum of Keratin Mutations

Epidermolysis bullosa simplex (EBS) is an inherited skin disorder caused by mutations in keratins K5 (keratin 5) and K14 (keratin 14), with fragility of basal keratinocytes leading to epidermal cytolysis and blistering. Patients present with widely varying severity and are classified in three main subtypes: EBS Weber-Cockayne (EBS-WC), EBS Köbner (EBS-K), and EBS Dowling-Meara (EBS-DM), based on distribution and pattern of blisters. We could identify K5/K14 mutations in 20 out of the 43 families registered as affected by dominant EBS in Scotland; with previous studies this covers 70% of all Scottish EBS patients, making this the most comprehensively analyzed EBS population. Nine mutations are novel. All mutations lie within five previously identified rod domain hotspots and the severest blistering was associated with mutations in the helix boundary motifs. In some cases, the same mutation caused symptoms of EBS-WC and/or EBS-K, both within and between families, suggesting a contribution of additional factors to the phenotype. In some patients, no mutations were found in K5, K14, or K15, suggesting involvement of other genes. The results confirm that EBS is best considered as a single disorder with a spectrum of phenotypic variations, from severe EBS-DM at one extreme to mild EBS-WC at the other.

Junctional epidermolysis bullosa

Epidermolysis bullosa (EB) encompasses a heterogeneous group of genodermatoses, characterized by fragility and blistering of the skin, often associated with extracutaneous manifestations. The level of vesiculation within the skin defines 3 major subtypes of EB: EB simplex, junctional EB, and dystrophic EB. We present the case of a male neonate of 36 weeks of gestation, who was born with a few blisters with erosions and who rapidly developed extensive blistering of the skin. Histopathology revealed subepidermal blistering. Electron microscopy confirmed the cleavage of epidermis from dermis within the lamina lucida. Junctional EB was the diagnosis. The patient was discharged after hospitalization for 28 days. The development of new blisters with erosions were gradually improved after AQUACEL Ag dressing, and the general condition was much better than at admission. The patient likely has a subtype of junctional EB termed generalized atrophic benign EB that clinically improves with age. He has the potential to father children and has a normal life expectancy.

Molecular epidemiology of hereditary epidermolysis bullosa in a Middle Eastern population

Epidermolysis bullosa (EB) encompasses a large group of inherited blistering skin disorders caused by mutations in at least 10 genes. Numerous studies, mainly performed in European and US families with EB, have revealed a number of characteristic epidemiological and genetic features, which form the basis for current diagnostic and counseling strategies. However, little is currently known about the molecular epidemiology of EB in Middle East populations. In the present study, we assessed 55 EB families for pathogenic sequence alterations in the 10 genes known to be associated with EB. Our results show unique EB subtype distribution and patterns of inheritance in our cohort. We also failed to detect recurrent mutations frequently encountered in Europe and the US, and did not consistently observe genotype-phenotype correlations formerly established in Western populations. Thus, the molecular epidemiology of EB in the Middle East is significantly different from that previously delineated in Europe and the US. Our data raise the possibility that similar differences may also be found in other genetically heterogeneous groups of disorders, and indicate the need for population-specific diagnostic and management approaches.

Death from colonic disease in epidermolysis bullosa dystrophica

BACKGROUND

Squamous cell carcinomas and renal failure were reported the causes of death in patients with recessive dystrophic epidermolysis bullosa (RDEB). Death from colonic disease in epidermolysis bullosa (EB) is never reported.

CASE PRESENTATION

We demonstrate a male patient with RDEB. He suffered megacolon due to fecal impaction and died from sigmoid colon perforation with peritonitis at age 35 years.

CONCLUSION

Constipation is a common clinical feature of RDEB, but fetal complications of chronic constipation are rarely reported. To the author's best knowledge, it has not been reported or recognized in the English literature previously. The aggressive assessment of constipation with fecal impaction is recommended in patients with RDEB.

A homozygous missense mutation in TGM5 abolishes epidermal transglutaminase 5 activity and causes acral peeling skin syndrome

Peeling skin syndrome is an autosomal recessive genodermatosis characterized by the shedding of the outer epidermis. In the acral form, the dorsa of the hands and feet are predominantly affected. Ultrastructural analysis has revealed tissue separation at the junction between the granular cells and the stratum corneum in the outer epidermis. Genomewide linkage analysis in a consanguineous Dutch kindred mapped the gene to 15q15.2 in the interval between markers D15S1040 and D15S1016. Two homozygous missense mutations, T109M and G113C, were found in TGM5, which encodes transglutaminase 5 (TG5), in all affected persons in two unrelated families. The mutation was present on the same haplotype in both kindreds, indicating a probable ancestral mutation. TG5 is strongly expressed in the epidermal granular cells, where it cross-links a variety of structural proteins in the terminal differentiation of the epidermis to form the cornified cell envelope. An established, in vitro, biochemical cross-linking assay revealed that, although T109M is not pathogenic, G113C completely abolishes TG5 activity. Three-dimensional modeling of TG5 showed that G113C lies close to the catalytic domain, and, furthermore, that this glycine residue is conserved in all known transglutaminases, which is consistent with pathogenicity. Other families with more-widespread peeling skin phenotypes lacked TGM5 mutations. This study identifies the first causative gene in this heterogeneous group of skin disorders and demonstrates that the protein cross-linking function performed by TG5 is vital for maintaining cell-cell adhesion between the outermost layers of the epidermis.

The molecular genetics of keratin disorders

Keratins are the type I and II intermediate filament proteins which form a cytoskeletal network within all epithelial cells. They are expressed in pairs in a tissue- and differentiation-specific fashion. Epidermolysis bullosa simplex (EBS) was the first human disorder to be associated with keratin mutations. The abnormal keratin filament aggregates observed in basal cell keratinocytes of some EBS patients are composed of keratins K5 and K14. Dominant mutations in the genes encoding these proteins were shown to disrupt the keratin filament cytoskeleton resulting in cells that are less resilient and blister with mild physical trauma. Identification of mutations in other keratin genes soon followed with attention focussed on disorders showing abnormal clumping of keratin filaments in specific cells. For example, in bullous congenital ichthyosiform erythroderma, clumping of filaments in the suprabasal cells led to the identification of mutations in the suprabasal keratins, K1 and K10. Mutations have now been identified in 18 keratins, all of which produce a fragile cell phenotype. These include ichthyosis bullosa of Siemens (K2e), epidermolytic palmoplantar keratoderma (K1, K9), pachyonychia congenita (K6a, K6b, K16, K17), white sponge nevus (K4, K13), Meesmann's corneal dystrophy (K3, K12), cryptogenic cirrhosis (K8, K18) and monilethrix (hHb6, hHb1).In general, these disorders are inherited as autosomal dominant traits and the mutations act in a dominant-negative manner. Therefore, treatment in the form of gene therapy is difficult, as the mutant gene needs to be inactivated. Ways of achieving this are actively being studied. Reliable mutation detection methods from genomic DNA are now available. This enables rapid screening of patients for keratin mutations. For some of the more severe phenotypes, prenatal diagnosis may be requested and this can now be performed from chorionic villus samples at an early stage of the pregnancy. This review article describes the discovery of, to date, mutations in 18 keratin genes associated with inherited human diseases.

The clinical spectrum of epidermolysis bullosa simplex

As part of the U.K. National Epidermolysis Bullosa Register, we have systematically recorded clinical information on 130 (77%) of the 168 known Scottish epidermolysis bullosa simplex (EBS) sufferers. Three subtypes of EBS were recognized: Dowling-Meara (EBS-DM), Weber-Cockayne (EBS-WC) and Köbner (EBS-Kb), seen in 5%, 42% and 53% of patients, respectively. As there is considerable overlap between EBS-WC and EBS-Kb, with both phenotypes frequently seen within the same pedigree, EBS-WC is best regarded as a milder variant of EBS-Kb rather than a separate disorder. Improvement with age is common in all variants of EBS, but is not invariable. Pain due to acral blistering in EBS-Kb/EBS-WC has a more marked impact on life-style than the blisters of EBS-DM. Oral blistering, nail involvement and aplasia cutis congenita occur in all EBS subtypes and laryngeal involvement is a feature of EBS-DM. Seasonal variation is not seen in EBS-DM but is common in EBS-Kb/EBS-WC.

Human keratin diseases: the increasing spectrum of disease and subtlety of the phenotype-genotype correlation

Keratins are obligate heterodimer proteins that form the intermediate filament cytoskeleton of all epithelial cells. Keratins are tissue and differentiation specific and are expressed in pairs of types I and II proteins. The spectrum of inherited human keratin diseases has steadily increased since the causative role of mutations in the basal keratinocyte keratins 5 and 14 in epidermolysis bullosa simplex (EBS) was first reported in 1991. At the time of writing, mutations in 15 epithelial keratins and two trichocyte keratins have been associated with human diseases which include EBS, bullous congenital ichthyosiform erythroderma, epidermolytic palmoplantar keratoderma, ichthyosis bullosa of Siemens, diffuse and focal non-epidermolytic palmoplantar keratoderma, pachyonychia congenita and monilethrix. Mutations in extracutaneous keratins have been reported in oral white sponge naevus and Meesmann's corneal dystrophy. New subtleties of phenotype-genotype correlation are emerging within the keratin diseases with widely varying clinical presentations attributable to similar mutations within the same keratin. Mutations in keratin-associated proteins have recently been reported for the first time. This article reviews clinical, ultrastructural and molecular aspects of all the keratin diseases described to date and delineates potential future areas of research in this field.

Mutations in keratin K9 in kindreds with epidermolytic palmoplantar keratoderma and epidemiology in Northern Ireland

Epidermolytic palmoplantar keratoderma (EPPK, MIM #144200) is an autosomal dominant disorder in which hyperkeratosis confined to the palms and soles is characterized histologically by cytolysis of suprabasal keratinocytes. Mutations in the keratin 9 gene (KRT9), a type 1 keratin expressed exclusively in the suprabasal keratinocytes of palmoplantar epidermis, have previously been demonstrated in this disorder. Here, we have studied four Northern Irish kindreds presenting with EPPK. By direct sequencing of polymerase chain reaction products, heterozygous missense mutations in exon 1 of KRT9 were detected in all the families. These included a novel mutation M156T; as well as M156V in two kindreds; and R162Q in the remaining family. All mutations were confirmed by reverse strand sequencing and restriction enzyme analysis. The point prevalence of EPPK in Northern Ireland was found to be 4.4 per 100,000. To date, all reported EPPK mutations occur in the helix initiation motif at the start of the central coiled-coil rod domain of K9.