Rapid prenatal diagnosis of epidermolysis bullosa letalis using GB3 monoclonal antibody

Gene-edited cells: novel allogeneic gene/cell therapy for epidermolysis bullosa

Epidermolysis bullosa (EB) is a group of rare genetic skin fragility disorders, which are hereditary. These disorders are associated with mutations in at least 16 genes that encode components of the epidermal adhesion complex. Currently, there are no effective treatments for this disorder. All current treatment approaches focus on topical treatments to prevent complications and infections. In recent years, significant progress has been achieved in the treatment of the severe genetic skin blistering condition known as EB through preclinical and clinical advancements. Promising developments have emerged in the areas of protein and cell therapies, such as allogeneic stem cell transplantation; in addition, RNA-based therapies and gene therapy approaches have also become a reality. Stem cells obtained from embryonic or adult tissues, including the skin, are undifferentiated cells with the ability to generate, maintain, and replace fully developed cells and tissues. Recent advancements in preclinical and clinical research have significantly enhanced stem cell therapy, presenting a promising treatment option for various diseases that are not effectively addressed by current medical treatments. Different types of stem cells such as primarily hematopoietic and mesenchymal, obtained from the patient or from a donor, have been utilized to treat severe forms of diseases, each with some beneficial effects. In addition, extensive research has shown that gene transfer methods targeting allogeneic and autologous epidermal stem cells to replace or correct the defective gene are promising. These methods can regenerate and restore the adhesion of primary keratinocytes in EB patients. The long-term treatment of skin lesions in a small number of patients has shown promising results through the transplantation of skin grafts produced from gene-corrected autologous epidermal stem cells. This article attempts to summarize the current situation, potential development prospects, and some of the challenges related to the cell therapy approach for EB treatment.

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.

Carmi Syndrome in a Preterm Neonate: A Multidisciplinary Approach and Ethical Challenge

Epidermolysis bullosa (EB) is characterized by blistering of the skin and mucosal erosions caused by hemidesmosomal abnormalities. EB is divided into 3 major subgroups depending on the particular location of tissue separation: EB simplex, dystrophic EB, and junctional EB. Junctional EB (JEB) can further be broken down into Herlitz, non-Herlitz, and JEB with pyloric atresia (Carmi syndrome) depending on genetic and histologic testing. When extensive, management of a patient with EB can be challenging due to not only cutaneous but also extracutaneous manifestations as well. Families and health care teams are often faced with difficult decisions in their infant's best interest. We report a case of a preterm neonate with Carmi syndrome and unique findings on immunofluorescence studies. The patient's course was complicated by multisystem involvement and ultimately death. A multidisciplinary approach was crucial in the light of diagnostic, therapeutic, and ethical challenges.

Epidermolysis bullosa and congenital pyloric atresia

The association between epidermolysis bullosa (EB) and pyloric atresia (PA) is rare but well documented. Herein, we report a case of EB associated with congenital PA. A female baby, weighing 1480 g, was born vaginally to a 31-year-old gravida 7 lady at 33 weeks of gestation. Polyhydramnios was detected on antenatal assessment. The parents were non-consanguineous Saudis with no family history of significant illness. At birth, well-demarcated areas of peeled skin were present over knees, left leg and periumbilical region. Systemic examination revealed no other abnormality. On second day, the patient developed recurrent vomiting and abdominal distension. An abdominal X-ray revealed a single gastric gas bubble suggesting pyloric obstruction. Following gastroduodenostomy, the baby developed severe sepsis with multiorgan dysfunction and expired on 25th day of life. Skin biopsy showed cleavage within lamina lucida.

Inherited epidermolysis bullosa: past, present, and future

Inherited epidermolysis bullosa encompasses dozens of diseases characterized by mechanical fragility of the skin, blister formation, and abnormal wound healing. Most of the more severe subtypes are associated with clinically significant extracutaneous complications. Some subtypes may lead to death, even in early infancy. Over the past two decades substantial advances have been made to our understanding of the underlying molecular basis for each member of this protean group of diseases. Research has now shifted toward the identification of therapeutic interventions, to include gene therapy, recombinant protein infusions, intradermal injection of allogeneic fibroblasts, and stem cell transplantation, that might eventually lead to a definitive cure for this disease. Other developing therapies being explored are directed toward the enhancement of wound healing and the prevention of potentially life-threatening skin cancers in these patients.

Prenatal diagnosis for severe inherited skin disorders: 25 years' experience

BACKGROUND

Over the last 25 years there have been major advances in methods for prenatal testing of inherited skin disorders. Since 1979, our group at the St John's Institute of Dermatology has performed 269 prenatal diagnoses, using a variety of approaches, including fetal skin biopsy (FSB), chorionic villus sampling (CVS) and preimplantation genetic diagnosis (PGD).

OBJECTIVES

This study was designed to review the clinical indications, testing procedures and laboratory analyses for all prenatal tests conducted at St John's over this period.

METHODS

FSBs were examined for morphological and, when relevant or feasible, immunohistochemical abnormalities. The DNA-based tests involved screening by nucleotide sequencing, restriction enzyme digests or, in a few cases, by linkage analysis. Results Of the 269 tests, 191 were FSB, 76 were CVS and two were PGD. The major indications for FSB were epidermolysis bullosa (EB) (138 cases, including 88 junctional and 48 dystrophic), ichthyoses (37 cases, including 22 tests for harlequin ichthyosis) and oculocutaneous albinism (12 cases). Of the CVS procedures, 75 were for EB (40 junctional, 35 dystrophic) and one was for the EEC (ectrodactyly, ectodermal dysplasia, clefting) syndrome. Both of the PGD procedures were for the skin fragility-ectodermal dysplasia syndrome. All tests provided accurate diagnoses and the fetal loss rate was approximately 1% for both FSB and CVS.

CONCLUSIONS

The development of prenatal testing has proved to be of great benefit for individuals or couples at risk of having children with severe inherited skin disorders and, in the absence of a cure, prenatal testing along with appropriate counselling has become an important translational benefit of basic research and an integral part of clinical management.

Laminins and human disease

The laminin protein family has diverse tissue expression patterns and is involved in the pathology of a number of organs, including skin, muscle, and nerve. In the skin, laminins 5 and 6 contribute to dermal-epidermal cohesion, and mutations in the constituent chains result in the blistering phenotype observed in patients with junctional epidermolysis bullosa (JEB). Allelic heterogeneity is observed in patients with JEB: mutations that results in premature stop codons produce a more severe phenotype than do missense mutations. Gene therapy approaches are currently being studied in the treatment of this disease. A blistering phenotype is also observed in patients with acquired cicatricial pemphigoid (CP). Autoantibodies targeted against laminins 5 and 6 destabilize epithelial adhesion and are pathogenic. In muscle cells, laminin alpha 2 is a component of the bridge that links the actin cytoskeleton to the extracellular matrix. In patients with laminin alpha 2 mutations, the bridge is disrupted and mature muscle cells apoptose. Congenital muscular dystrophy (CMD) results. The role of laminin in diseases of the nervous system is less well defined, but the extracellular protein has been shown to serve an important role in peripheral nerve regeneration. The adhesive molecule influences neurite outgrowth, neural differentiation, and synapse formation. The broad spatial distribution of laminin gene products suggests that laminin may be involved in a number of diseases for which pathogenic mechanisms are still being unraveled.

Laminins of the dermo-epidermal junction

Laminins are the most abundant structural non-collagenous glycoproteins ubiquitously present in basement membranes. They are multidomain molecules constituting a family of possibly more than 50 members. Some members such as laminins 5, 6 and 10 are specific of the basal lamina present under stratified epithelia. Although only few intact laminin isoforms have been purified from cultivated cells or tissues, genetic engineering has opened the way for a rapid development of laminin structural biology. Moreover, the phenotypes resulting from gene targeting in mouse or from laminin defects in acquired or inherited human diseases highlight the pivotal role of laminins in morphogenesis, development, and physiology. Indeed, the laminins display a remarkable repertoire of functions, most importantly as structural elements forming a network throughout the basement membrane to which other collagenous or non-collagenous glycoproteins and proteoglycans attach. Furthermore, they are signaling molecules providing adjacent cells with diverse information by interacting with cell surface components.

Altered expression of epithelial integrins and extracellular matrix receptors in oral erythema multiforme

Inflammation and ulceration at the epithelium-connective tissue interface, a characteristic of erythema multiforme (EM), may be associated with altered molecular attachment of basal keratinocytes. To determine the expression of basal keratinocyte-associated integrins and their basement membrane ligands in oral EM, specimens of clinically and microscopically confirmed EM (n = 12) and mucosal controls (n = 7) were stained immunohistochemically for the integrins alpha 3, beta 6, beta 1, and beta 4 and for extracellular matrix proteins laminin 1, laminin 5, collagen IV, and collagen VII using a standard avidin-biotin-peroxidase technique. In EM, results showed increased staining intensity for all integrins studied in basal and suprabasal keratinocytes. Basement membrane-associated staining of a6 and b4 was intense, but disrupted and fragmented. In EM, integrin staining was most marked at the summit of the connective tissue papillae. Laminin 5 staining was more intense than in controls, was frequently fragmented, and extended into the lamina propria. Laminin 1 staining was discontinuous and was frequently less intense than in controls. Collagen IV staining in EM was interrupted along the basement membrane. Collagen VII staining was fragmented but unchanged in intensity. These alterations in interface adhesion molecules suggest that hemidesmosome-associated molecules are important in the pathogenesis of EM. The staining intensities and patterns of expression of these adhesion molecules suggest that oral EM is initially focused in the connective tissue papillae.

Gamma 2 chain of laminin-5 is recognized by monoclonal antibody GB3

Herlitz junctional epidermolysis bullosa is an autosomal recessive disorder characterized by generalized blistering at the lamina lucida of the cutaneous basement membrane. The monoclonal antibody GB3 has been used as a diagnostic probe because of its lack of reactivity in patient skin. The antigen recognized by GB3 has been identified as laminin-5, a glycoprotein consisting of three subunits (alpha 3, beta 3 and gamma 2). To identify the laminin-5 protein chain that contains the epitope recognized by GB3 and to determine if chain assembly is required for antibody recognition, we expressed a gamma 2 protein constructed from a full-length gamma 2 cDNA. Radioimmunoprecipitation of the culture medium from 293 cells revealed that both GB3 and anti-gamma 2 polyclonal antibodies were capable of directly precipitating recombinant gamma 2 without coprecipitation of other proteins. In immunodepletion experiments, each antibody removed most of the protein that was reactive with the other antibody. The epitope recognized by GB3 is present only when the complex is in the native conformation because GB3 reacted only with the non-reduced laminin-5, but not the reduced laminin-5 in immunoblots. Moreover, because GB3 reacted with laminin-5 of SCC25 cells (gamma 2 in the heterotrimer) but not recombinant gamma 2 in 293 cells (gamma 2 alone) during indirect immunofluorescence staining, this epitope may be dependent upon a less stable conformation of gamma 2. We conclude that GB3 recognizes the gamma 2 chain of laminin-5 and that the epitope is entirely contained in the native form of the gamma 2 chain.

Genetic basis of lethal junctional epidermolysis bullosa in an affected fetus: implications for prenatal diagnosis in one family

Fetal skin biopsy at 20 weeks' gestation in a woman at risk for a child with the lethal skin-blistering disorder junctional epidermolysis bullosa (Herlitz) confirmed an affected fetus. Genomic DNA from the aborted fetus was examined for mutations in laminin 5, a macromolecule involved in adhesion at the dermal-epidermal junction, and a candidate protein in this condition. Polymerase chain reaction (PCR) amplification of exon 10 and parts of the flanking introns of the gene encoding the beta 3 chain of laminin 5 (LAMB3) and subsequent analysis by agarose gel electrophoresis showed a more slowly migrating band in the affected fetus compared with the normal control. Nucleotide sequencing of the abnormal PCR product revealed a homozygous 77 bp duplication within the exon, resulting in a premature termination codon 250 bp downstream from the 3' end of the duplication. Maternal DNA was heterozygous for the mutant and wild-type alleles. These findings illustrate the genetic basis of the skin disease in this case and also offer the prospects of a simple, rapid, and reliable first-trimester DNA-based prenatal, or even preimplantation, diagnostic test for future pregnancies in this family.

Prenatal exclusion of pyloric atresia-junctional epidermolysis bullosa syndrome

BACKGROUND

The pyloric atresia--junctional epidermolysis bullosa (PA-JEB) syndrome is an autosomal recessive disorder with a poor prognosis. Electron microscopy of fetal skin has been the only reliable method for prenatal diagnosis.

OBJECTIVE

The purpose of this study was to make the prenatal diagnosis of PA-JEB syndrome with a more reliable method by means of immunocytochemical probes.

METHODS

Expression of a range of basement membrane antigens was examined in different types of JEB. On the basis of the results, a fetal skin biopsy specimen was obtained for prenatal diagnosis.

RESULTS

In PA-JEB syndrome (n = 2), GB3 antigen (BM600) was normally expressed; the 19-DEJ-1 antigen was completely absent. In fetal skin at risk for PA-JEB syndrome, the 19-DEJ-1 antigen was normally expressed, and no ultrastructural abnormality was found by electron microscopy. A normal male infant was delivered at 38 weeks of pregnancy.

CONCLUSION

19-DEJ-1 monoclonal antibody serves as a useful probe for the prenatal diagnosis of PA-JEB syndrome.

The National Epidermolysis Bullosa Registry

Since its inception in 1986, the NEBR has proved to be an excellent example of how a relatively small allocation of federal research funds for the development of a registry of cases of a single rare disease can have a major impact on the rapid expansion in the depth of knowledge of not only the disease itself but of a number of associated biologic principles, including keratinization and epithelial cell-extracellular matrix interactions. At present, the NEBR is generating extensive clinical, laboratory, and demographic data, both from cross-sectional and longitudinal perspectives, as well as establishing a centralized cell and tissue bank that will serve the scientific community at large as a valuable resource for future basic research on this oftentimes devastating genetic disease.

Developmental expression of nicein adhesion protein (laminin-5) subunits suggests multiple morphogenic roles

Nicein/kalinin (laminin-5) is a heterotrimeric laminin-like adhesion protein, which is secreted at the basement membrane of subsets of epithelia and is involved in the etiology of junctional epidermolysis bullosa, a severe human blistering disease characterized by disadhesion of epidermis from dermis. cDNA clones encoding the three chains of mouse nicein and antibodies specific to each polypeptide were used to examine the expression of the protein in the developing mouse embryo from 10.5 day post coitum to 7 days after birth. At various stages of development, co-expression of the three chains of nicein was observed in amnion, skin, and in epithelia of respiratory, urinary and digestive systems. High level expression of nicein was seen in enamel-secreting ameloblasts in developing teeth. Cell-specific distribution of nicein was also detected in other specialized tissues representative of the three primary embryonic germ layers with prominent secretory or protective functions. Differential and focal expression of nicein subunits was observed in the choroid plexus and the floor plate of the neural tube. Messenger for the heavy chain of nicein was detected in the floor plate, where mouse s-laminin messengers were also found. This suggests that nicein genes may play a role in the migration and polarization of motor neurons in the developing spinal cord.

Immunofluorescent analysis of the basement membrane zone in lichen planus suggests destruction of the lamina lucida in bullous lesions

Lichen planus is an inflammatory dermatosis which is characterized histologically by an intense lymphocytic infiltrate at the dermal epidermal junction. This frequently results in disruption of the basement membrane zone, occasionally causing clinical blisters. In order to better understand the specific portion of the basement membrane zone which is disrupted by the lymphocytic infiltrate, we examined 7 cases of lichen planus with antibodies directed against anchoring filaments (GB3), the bullous pemphigoid antigen, anchoring fibrils (type VII collagen) and type IV collagen. In lesions without separation at the BMZ, all antibodies were strongly expressed, as in normal skin. In lesions with early separation, there was a focal decrease in GB3 staining, but types VII and IV collagen labelled normally. In lesions resulting in blisters, GB3 staining was essentially absent, and anti-types IV and VII collagen remained, but stained in a disrupted, less discrete pattern. The bullous pemphigoid antigen showed only slight deviation from the normal staining pattern. These findings suggest that the basement membrane zone in lichen planus is disrupted in the lamina lucida region. The lamina densa and sub-lamina densa zones remain intact even in bullous lesions of lichen planus.

Kalinin is abnormally expressed in epithelial basement membranes of Herlitz's junctional epidermolysis bullosa patients

Kalinin is an extracellular adhesion molecule specific to epithelial basement membranes (BM) identified as a component of anchoring filaments of hemidesmosomes. This heterotrimeric protein is synthesized by cultured normal human keratinocytes and is involved in cell attachment. In indirect immunofluorescence studies, the epidermal BM of patients with junctional epidermolysis bullosa (JEB) of Herlitz's type were found not to be reactive with the anti-kalinin monoclonal antibodies ka146 and K140 and displayed a decreased immunoreactivity to two anti-kalinin antibodies cross-reacting with K-laminin, an anchoring filament component recently described. The intrinsic defect of JEB keratinocytes in the synthesis of kalinin was further documented by indirect immunofluorescence on in vitro cultures of these cells. In non-Herlitz JEB patients, staining of BM was constantly detected. Impairment of expression of kalinin correlated with the lack of reactivity to the monoclonal antibody GB3, which detects the BM component nicein/BM600. These results clearly demonstrate a defect of kalinin expression in epithelial basement membranes of Herlitz JEB patients and suggest that kalinin may play a role in the pathogenesis of the disease. Further studies are in progress to define possible relationships between kalinin and nicein.

Diagnosis and prenatal diagnosis of epidermolysis bullosa herpetiformis (Dowling-Meara) in a mother, two affected children, and an affected fetus

In utero skin biopsy was performed on a fetus at risk of an uncertain form of epidermolysis bullosa (EB). The mother had produced two affected offspring diagnosed variously as having junctional or dystrophic EB. The two offspring and the fetus were products of different fathers. The mother claimed to have no disease and on clinical examination was without blisters. Examination of the fetal skin biopsy by light and electron microscopy revealed separation of the epidermal sheet from the majority of the biopsy sample, although occasional remnants of basal cells remained associated with the basement membrane. Aggregations of keratin filaments were observed within basal cells of the detached epidermis and in the attached basal cell remnants. The diagnosis was thus suggested to be epidermolysis bullosa Dowling-Meara. Re-review of the clinical and laboratory data from the affected infants revealed a clinical and histological pattern consistent with this diagnosis. Further discussion with the mother revealed that her skin had blistered as a child and that she presently had hyperkeratotic palms and soles. This history is consistent with the autosomal dominantly inherited epidermolysis bullosa herpetiformis (Dowling-Meara). This is the first reported prenatal diagnosis of EB Dowling-Meara. The morphological criteria of intraepidermal blistering and clumped keratin filaments within basal and immediately suprabasal cells characteristic of an affected individual postnatally also identified an affected fetus. There is, however, insufficient experience to be certain that these findings will hold from region to region in the body or among all affected fetuses, and thus prenatal diagnosis on a morphological basis should still be made with caution.

Aplasia cutis congenita associated with epidermolysis bullosa and pyloric atresia: the diagnostic role of prenatal ultrasonography

Aplasia cutis congenita associated with epidermolysis bullosa and pyloric atresia is a rare congenital disease in which localized or widespread areas of skin are absent at birth. Alphafetoprotein (AFP) and skin biopsy have been used for prenatal diagnosis of this condition. A patient in whom normal levels of amniotic AFP at 16 weeks' gestation presumably excluded the disease and who was at risk for aplasia cutis congenita associated with epidermolysis bullosa and pyloric atresia is described. However, 10 weeks later, ultrasonographic examination revealed hydramnios, a dilated stomach, a deformed external ear, and a contracted fisted hand. All signs were confirmed postnatally. The role of ultrasonography and the value of other diagnostic methods in this congenital disease are discussed.

Lethal junctional epidermolysis bullosa with normal expression of BM 600 and antro-pyloric atresia: a new variant of junctional epidermolysis bullosa?

A newborn girl is described with a lethal junctional epidermolysis bullosa (Herlitz form) (JEB) associated with a congenital localized absence of skin, and a pyloric atresia (PA). The post-mortem examination of the digestive tract showed a widespread cleavage between the epithelium and the chorion. Immunohistological and electron microscopical examination showed a cleavage occurring through the lamina lucida of the digestive basement membrane, as for the skin blisters. Despite the lethal character of this form of JEB, the BM 600 glycoprotein was normally recognized at the dermo-epidermal junction by the monoclonal antibody GB3. This rare association of lethal JEB-PA-localized absence of skin, with a quite unusual GB3 positive immunophenotype could correspond to a new variant of JEB.

Structure and antigenicity of the skin basement membrane zone

The skin basement membrane zone is comprised of two major ultrastructural regions, four associated structures, and at least 17 different antigens. In this brief review, the ultrastructure, antigenicity, and ontogeny of normal human skin will be discussed in detail, as will alterations in expression or immune response to selected basement membrane components in specific mechanobullous and autoimmune diseases.

Alpha-fetoprotein and acetylcholinesterase are not predictive of fetal junctional epidermolysis bullosa, Herlitz variant

Junctional epidermolysis bullosa, Herlitz variant (junctional EB-Herlitz) is a lethal autosomal recessive skin disorder currently amenable to prenatal diagnosis only by direct analysis of fetal skin. However, elevated levels of alpha-fetoprotein, as well as the presence of acetylcholinesterase in amniotic fluid, have been associated with other severe fetal genodermatoses. Fetal skin samplings were performed in ten pregnancies at risk for fetal junctional EB-Herlitz, with three fetuses affected on the basis of electron microscopic detection of blisters within the lamina lucida and abnormal hemidesmosomes. In neither affected nor unaffected pregnancies were maternal serum or amniotic fluid alpha-fetoprotein levels elevated. Moreover, alpha-fetoprotein levels in both maternal serum and amniotic fluid were not statistically different comparing affected and unaffected fetuses. Acetylcholinesterase was not present in the amniotic fluid samples of the three affected pregnancies. Unlike other severe fetal genodermatoses, neither alpha-fetoprotein nor acetylcholinesterase was predictive of junctional EB-Herlitz.

Revised clinical and laboratory criteria for subtypes of inherited epidermolysis bullosa. A consensus report by the Subcommittee on Diagnosis and Classification of the National Epidermolysis Bullosa Registry

Inherited epidermolysis bullosa encompasses a number of diseases, with the common finding of blister formation after minor mechanical trauma to the skin. In some forms significant, if not eventually fatal, extracutaneous disease activity may occur. In recent years application of newer technologies has contributed substantially to an overall understanding of this collection of inherited diseases. Concurrently, many new phenotypes have been recognized, in part the result of ongoing prospective patient registries in the United States and abroad. Unfortunately, this has resulted in a massive literature that may appear to be confounded by seemingly excessive or arbitrary subdivision of epidermolysis bullosa variants. With these concerns in mind a subcommittee was established by the National Epidermolysis Bullosa Registry to summarize the current literature and to make recommendations as to the best clinical and laboratory criteria for the practical diagnosis and subclassification of patients with inherited epidermolysis bullosa.

GB3 monoclonal antibody for the diagnosis of junctional epidermolysis bullosa: results of a multicenter study

GB3 monoclonal antibody detects a normal basement membrane component (GB3 antigen) that is variably expressed in junctional epidermolysis bullosa. To assess the accuracy of GB3 in the diagnosis of junctional epidermolysis bullosa, we have reviewed its use in 250 cases of the major types of epidermolysis bullosa. In the majority of cases of the simplex and dystrophic forms of epidermolysis bullosa, GB3 antigen is normally expressed. In the Herlitz variant of junctional epidermolysis bullosa, GB3 antigen expression is consistently abnormal, but in the non-Herlitz and indeterminate forms of junctional epidermolysis bullosa, 40% of cases express GB3 antigen normally. We propose that GB3 monoclonal antibody is useful in the accurate identification of patients with Herlitz junctional epidermolysis bullosa and may prove equal to electron microscopy for the diagnosis of this disease. For the non-Herlitz variants, it should not be used as an alternative to electron microscopy but may be of special value in the determination of prognosis.

Prenatal diagnosis of junctional epidermolysis bullosa associated with pyloric atresia

Prenatal diagnosis of junctional epidermolysis bullosa associated with pyloric atresia was carried out in a couple at risk. Their two previous children had died during the first months of life of the same disorder despite surgery for the pyloric abnormality. Ultrastructural study of fetal skin biopsies obtained at 18 weeks' gestation showed dermal-epidermal separation at the lamina lucida level, while ultrasound showed marked stomach dilatation. Light microscopy of pyloric tissue obtained after termination showed the pyloric lumen to be replaced by loose connective tissue with no inflammatory reaction. Immunofluorescence studies on the skin specimens with the monoclonal antibody GB3, known to be absent in 'lethal' junctional epidermolysis bullosa skin, disclosed a marked positivity suggesting that the junctional epidermolysis bullosa in this case may be of the 'non-lethal' type.

Applicability of 19-DEJ-1 monoclonal antibody for the prenatal diagnosis or exclusion of junctional epidermolysis bullosa

Recently a monoclonal antibody (19-DEJ-1) was produced with binding specificity for the mid-lamina lucida of the skin dermo-epidermal junction, in very close association with overlying hemidesmosomes. Since skin cleavage occurs within the lamina lucida in the inherited blistering disorder, junctional epidermolysis bullosa (EB), and is associated with aberrations in the morphology and/or number of hemidesmosomes in such tissue, we have sought to determine whether this monoclonal antibody could be used for prenatal diagnosis. Fetoscopy-directed skin biopsies were obtained from two fetuses at risk for junctional EB and post-mortem samples from two other fetuses with the Herlitz type of junctional EB, the latter after prenatal diagnosis by electron microscopy and termination of each pregnancy. Specimens were examined in part by light and electron microscopy for evidence of skin cleavage or other alterations in morphology, and in part by indirect immunofluorescence for altered basement membrane antigenicity. Three of four fetuses were shown to have intra-lamina lucida blister formation indicative of, and hemidesmosome hypoplasia proving, junctional EB. Each was also shown to lack expression of GB3 and 19-DEJ-1 antigens, consistent with findings noted postnatally in junctional EB; diagnosis was confirmed in each at the time of therapeutic abortion. A fourth fetus had no abnormalities detected; lack of disease involvement was confirmed at the time of delivery, and subsequently over 8 months of careful serial evaluation. We conclude that 19-DEJ-1 monoclonal antibody is an accurate and sensitive immunohistochemical probe for junctional EB, and may be employed in the prenatal diagnostic evaluation of fetuses at risk for this disorder.

Chondroitin 6-sulfate proteoglycan but not heparan sulfate proteoglycan is abnormally expressed in skin basement membrane from patients with dominant and recessive dystrophic epidermolysis bullosa

Two distinct groups of proteoglycans, chondroitin 6-sulfate (C6-S) proteoglycan and heparan sulfate proteoglycan (HSPG), have been recently shown to reside within the lamina densa of normal human skin basement membrane (BM). To determine whether either or both antigens are normally expressed in one or more forms of epidermolysis bullosa (EB), a disease known to have specific alterations in skin BM, we have examined by indirect immunofluorescence 31 specimens of clinically normal skin from 28 EB patients (simplex, 5; junctional, 8; dominant dystrophic [DDEB], 9; recessive dystrophic [RDEB], 9) with monoclonal antibodies to C6-S and HSPG. HSPG was normally expressed in all EB and control skin specimens, whereas C6-S was absent along the dermoepidermal junction of 9 of 9 RDEB and 7 of 9 DDEB, and reduced in 2 of 9 DDEB cases. In contrast, C6-S was normally expressed in 5 of 5 EB simplex, 5 of 6 junctional EB, and all control skin specimens. We have subsequently extracted a greater than 400 kD C6-S proteoglycan from normal skin BM and have found that the core protein may also contain heparan sulfate side chains. Our findings suggest that 3B3 monoclonal antibody recognizes a hybrid proteoglycan in human skin, and that its absent or reduced binding in dystrophic EB skin BM may reflect either absence of associated core protein or posttranslational alterations in the proteoglycan side chains.

Prenatal diagnosis of dominant and recessive dystrophic epidermolysis bullosa: application and limitations in the use of KF-1 and LH 7:2 monoclonal antibodies and immunofluorescence mapping technique

Prenatal diagnosis is now possible for junctional and recessive dystrophic forms of epidermolysis bullosa (EB); however, there is no similar published experience for dominant dystrophic EB, although data with KF-1 monoclonal antibody suggests that both forms of dystrophic EB can be identified at least postnatally with this unique probe. We now report our experience with light microscopy, electron microscopy, immunofluorescence mapping, and KF-1 and LH 7:2 monoclonal antibodies, in both a mother with dominant dystrophic EB and her fetus at risk, and in a fetus previously shown to be affected with recessive dystrophic EB. KF-1 and LH 7:2 antigens were absent in recessive dystrophic EB fetal skin, identical to findings observed postnatally. LH 7:2 was normally expressed in a mother with dominant dystrophic EB and in her fetus at risk for this disease. In contrast, while KF-1 antigen was abnormally expressed in the affected mother, it was normally expressed in only 1/7 fetal biopsies despite the fact that this fetus was shown by light and electron microscopy and immunofluorescence mapping to be unaffected with dominant dystrophic EB. We conclude that 1) transmission electron microscopy can be used to prenatally exclude the diagnosis of dominant dystrophic EB (Cockayne-Touraine variety), 2) immunofluorescence mapping is an accurate technique for prenatal as well as postnatal diagnosis of EB, and 3) KF-1 cannot by itself be used as an accurate probe for the prenatal diagnosis of dominant dystrophic EB, due to the apparent variability in the time for the normal expression of KF-1 in fetal skin during the second trimester.