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

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.

Connective tissue and related disorders and preterm birth: clues to genes contributing to prematurity

To identify candidate genes contributing to preterm birth, we examined the existing literature on the association between known disorders of connective tissue synthesis and metabolism and related diseases and prematurity. Our hypothesis was that abnormal matrix metabolism contributes to prematurity by increasing risk of preterm premature rupture of membranes (PPROM) and cervical incompetence. Based on this review, we identified gene mutations inherited by the fetus that could predispose to preterm birth as a result of PPROM. The responsible genes include COL5A1, COL5A2, COL3A1, COL1A1, COL1A2, TNXB, PLOD1, ADAMTS2, CRTAP, LEPRE1 and ZMPSTE24. Marfan syndrome, caused by FBN1 mutations, and polymorphisms in the COL1A1 and TGFB1 genes have been associated with cervical incompetence. We speculate that an analysis of sequence variation at the loci noted above will reveal polymorphisms that may contribute to susceptibility to PPROM and cervical incompetence in the general population.

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.

Clinical criteria for differentiating between recessive and dominant forms of dystrophic epidermolysis bullosa, elaborated from an analysis of 119 cases

We attempted to establish clinical criteria which differentiated between recessive dystrophic epidermolysis bullosa (RDEB) and dominant DEB (DDEB), since these two groups show prominent differences in prognosis, genetic recurrence risk and response to some types of treatment. The total of 119 cases examined consisted of our own 9 cases (2 of RDEB and 7 of DDEB) and 110 cases (26 of RDEB and 84 of DDEB) collected from the medical literature. They were analyzed by calculating the sensitivity and specificity of ten clinical features. We concluded that, syndactyly, presence of complications, dental lesions, remission-less course, and oral lesions are strongly indicative of RDEB (more than 70% specific). Intractable skin ulcer is suggestive of RDEB (more than 55% specific). Nail lesions, scar and atrophy, milia and pigmentation are not helpful in the differentiation because of their commonality. The proposed criteria are simple, reliable, and practical, providing us with a useful tool for differentiation of RDEB and DDEB in daily practice.

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.

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.

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.

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.