Epidermolysis bullosa pruriginosa: dystrophic epidermolysis bullosa with distinctive clinicopathological features

Dystrophic epidermolysis bullosa: pathogenesis and clinical features

Dystrophic epidermolysis bullosa (DEB) is relatively well understood. Potential therapies are in development. This article describes the pathogenesis and clinical features of DEB. It also describes therapeutic options and the future of molecular therapies.

Mutation analysis and characterization of COL7A1 mutations in dystrophic epidermolysis bullosa

Dystrophic epidermolysis bullosa (DEB) is inherited in both an autosomal dominant DEB and autosomal recessive manner RDEB, both of which result from mutations in the type VII collagen gene (COL7A1). To date, 324 pathogenic mutations have been detected within COL7A1 in different variants of DEB; many mutations are clustered in exon 73 (10.74%) which is close to the 39 amino acid interruption region. Dominant dystrophic epidermolysis bullosa usually involves glycine substitutions within the triple helix of COL7A1 although other missense mutations, deletions or splice-site mutations may underlie some cases. In recessive dystrophic epidermolysis bullosa, the mutations include nonsense, splice site, deletions or insertions, 'silent' glycine substitutions within the triple helix and non-glycine missense mutations within the triple helix or non-collagenous NC-2 domain. The nature of mutations in COL7A1 and their positions correlate reasonably logically with the severity of the resulting phenotypes.

Clinical and molecular dilemmas in the diagnosis of familial epidermolysis bullosa pruriginosa

Dystrophic epidermolysis bullosa is a rare and clinically heterogeneous mechanobullous disorder. One unusual clinical variant is epidermolysis bullosa pruriginosa (EBP), in which the combination of pruritus and skin fragility can lead to hypertrophic, lichenified nodules and plaques. This form of inherited epidermolysis bullosa may not develop clinically until adult life, leading to diagnostic confusion with acquired disorders, such as nodular prurigo, lichen simplex, lichen planus, hypertrophic scarring, or dermatitis artefacta. As in all other forms of dystrophic epidermolysis bullosa, the molecular pathology involves mutations in the gene encoding the anchoring fibril protein, type VII collagen (COL7A1), but there is no clear genotype-phenotype correlation in EBP. In this report, we describe a Chinese-Singaporean family with EBP in whom an autosomal dominant glycine substitution mutation, p.G2251E, was identified in exon 86 of the COL7A1 gene. This heterozygous mutation was identified in the genomic DNA of all 4 affected adults tested, as well as 2 clinically unaffected offspring (aged 9-29 years). Based on DNA sequencing, we predict that these individuals may develop EBP later in life, although additional factors leading to disease expression may determine phenotypic expression. Nevertheless, we plan to closely monitor these potentially presymptomatic individuals for symptoms of pruritus and early signs of the genetic disorder.

Review of collagen VII sequence variants found in Australasian patients with dystrophic epidermolysis bullosa reveals nine novel COL7A1 variants

BACKGROUND

Dystrophic epidermolysis bullosa (DEB) is an inherited skin fragility disorder where blistering occurs in the sub-lamina densa zone at the level of anchoring fibrils (AFs) of the dermo-epidermal junction. Both autosomal dominant (DDEB) and recessive (RDEB) result from mutations in the type VII collagen gene (COL7A1).

OBJECTIVE

The purpose of this study was to understand the genotype-phenotype correlation in Australian patients with DEB.

METHODS

Skin biopsies from patients were processed for immunofluorescence mapping, the COL7A1 gene was screened for sequence variants.

RESULTS

We report 14 Australian families with different forms of dystrophic epidermolysis bullosa (DEB) with 23 different COL7A1 allelic variants, nine of which were novel. Four cases of RDEB-HS combined two premature termination codon (PTC) variants and three other cases of RDEB-HS with combined PTC and spice-site or glycine substitution variants. G2043R, a de novo dominant variant, was also identified in this study. Four "silent" glycine substitutions were found in this study, G2775S, G1673R, G1338V and G2719A. EB17, with combined R2791W and G2210V variants, had a DDEB-Pasini phenotype, in contrast to two family members who had severe DDEB pruriginosa, with the same genotype.

CONCLUSION

In this study, the RDEB variants included nonsense variants, splice site variants, internal deletions or insertions, "silent" glycine substitutions within the triple helix or N or C terminal ends of the triple helix and non-glycine missense variants within the triple helix domain. DDEB usually involves glycine substitutions within the triple helix of COL7A1 although other missense variants or splice-site alterations may underlie some cases.

Dystrophic epidermolysis bullosa pruriginosa in Italy: clinical and molecular characterization

Dystrophic epidermolysis bullosa (DEB) pruriginosa (DEB-Pr) is a rare variant of DEB due to COL7A1 dominant and recessive mutations, which is characterized by severe itching and lichenoid or nodular prurigo-like lesions, mainly involving the extremities. Less than 30 patients have been described showing variable disease expression, and frequently, delayed age of onset. We report the clinical and molecular characterization of seven Italian DEB patients, three affected with recessive DEB-Pr and four with dominant DEB-Pr. In all the patients, the signs were typical of a mild DEB phenotype, until the onset of pruritus, which was followed by worsening of the clinical picture, with appearance of the distinctive lichenified lesions of DEB-Pr. Nine mutations were found in the COL7A1 gene, three of which were novel and one was de novo. DEB-Pr patients with either dominant or recessive mutations were shown to synthesize a normal or variably reduced amount of type VII collagen, which was correctly deposited at the dermal-epidermal junction. Since six of these mutations have been reported in DEB patients in the absence of intense pruritus, these data implicate a role of yet unidentified phenotype-modifying factors in the pathogenesis of DEB-Pr.

Transient bullous dermolysis of the newborn in three generations

Transient bullous dermolysis of the newborn (TBDN) is a rare form of dystrophic epidermolysis bullosa (DEB) that presents with neonatal skin blistering but which usually improves markedly during early life or even remits completely. Skin biopsies reveal abnormal intraepidermal accumulation of type VII collagen which results in poorly constructed anchoring fibrils and a sublamina densa plane of blister formation. The reason for the spontaneous clinical improvement is not known, but there is a gradual recovery in type VII collagen secretion from basal keratinocytes to the dermal-epidermal junction, with subsequent improvement or correction of anchoring fibril morphology. In this report, we describe TBDN occurring in three generations of the same family. Blistering occurred only during the first few months after birth, and all affected individuals were found to have a heterozygous glycine substitution mutation in exon 45 of the type VII collagen gene, COL7A1, designated G1522E. This mutation represents the third report of a pathogenic COL7A1 mutation in TBDN. Despite limited understanding of the disease mechanism in TBDN, this distinct form of DEB is important to recognize as it typically has a benign and self-limiting course. However, not all cases of DEB associated with intraepidermal type VII collagen are 'transient'. Genetic counselling in such patients therefore should be guarded until the pathophysiology of TBDN is better understood.

Epidermólise bolhosa distrófica pruriginosa: relato de caso

A epidermólise bolhosa distrófica pruriginosa é doença genética rara cujo padrão de herança ainda não está bem estabelecido na literatura. O defeito genético, que envolve a codificação do colágeno tipo VII, está localizado no braço curto do cromossomo 3, ocorrendo mutação no gene COL7A1. Apresenta-se o caso de um paciente do sexo masculino que referia prurido nas pernas há cerca de 15 anos, cujo diagnóstico foi firmado com base nos exames dermatológico e imuno-histopatológico. Devido à raridade dessa condição patológica, realiza-se breve revisão do tema.

Thalidomide in the management of epidermolysis bullosa pruriginosa

Epidermolysis bullosa (EB) pruriginosa is a distinctive clinical subtype of dystrophic EB. We report a patient with dominant dystrophic EB pruriginosa, who had an excellent response to systemic thalidomide treatment. The mechanism of action of thalidomide in the management of pruriginous disorders is not yet completely understood. Most recent studies point towards an immunomodulatory action of thalidomide that may suppress excessive production of tumour necrosis factor-alpha and may downregulate certain cell surface adhesion molecules involved in leucocyte migration.

Epidermolysis bullosa: pathophysiology and nursing care

Epidermolysis bullosa (EB) is defined as a group of skin disorders that presents as blistering of the skin in varying degrees of severity. Most cases are inherited, but rare cases may be acquired. There are three main types: simplex, junctional, and dystrophic. The dermal-epidermal junction of the newborn skin is a vital area of attachment. Any defects in the components that comprise this junction can lead to fragility of the skin. EB diagnosis and testing can be per formed both prenatally and postnatally. There is no cure for EB. Treatment revolves around supportive care and prevention of complications. The NICU nurse plays an important role on the multidisciplinary team as primary caregiver to the infant and educator to the family.

The G2028R glycine substitution mutation in COL7A1 leads to marked inter-familiar clinical heterogeneity in dominant dystrophic epidermolysis bullosa

BACKGROUND

Glycine substitution mutations in COL7A1 not only cause dominant dystrophic epidermolysis bullosa (DDEB), but can also be silent mutations which lead to recessive dystrophic epidermolysis bullosa (RDEB) in combination with additional mutations in the other allele.

OBJECTIVE

In this study, we have examined a large American Caucasian pedigree in which 10 family members from four generations presented with simple toenail dystrophy without skin fragility in autosomal dominant manner.

METHOD

We sequenced COL7A1 of this pedigree.

RESULTS

Mutational analysis indeed detected a heterozygous G-to-A transition at nucleotide position 6082 leading to G2028R in all the affected members. Surprisingly, mutation database revealed that this G2028R mutation had been previously identified in two distinct Asian families with DDEB showing apparent skin fragility and blister formation. One case was a 17-month-old Chinese female with classical phenotype of DDEB and the other was a 27-year-old Japanese female with typical epidermolysis bullosa (EB) pruriginosa. To better understand the molecular mechanisms of this marked inter-familiar clinical heterogeneity, we examined the entire sequence of all the exons and exon-intron borders as well as the promoter region of COL7A1 in all the three families. Sequence results demonstrated no significant nucleotide difference in COL7A1 among the three pedigrees.

CONCLUSION

This paper has demonstrated for the first time that identical COL7A1 glycine substitutions can cause remarkably heterogeneous clinical phenotypes extending from simple toe nail dystrophy without skin fragility to typical DDEB and EB pruriginosa. In addition, the fact of inter-familiar, not intra-familiar clinical heterogeneity associated with G2028R suggest that the other molecular mechanisms not controlled by COL7A1 coding sequence might be responsible for the clinical heterogeneity.

A novel missense mutation in the COL7A1 gene underlies epidermolysis bullosa pruriginosa

Epidermolysis bullosa (EB) pruriginosa is a subtype of dominant dystrophic EB (DDEB), characterized by severe pruritus and blistering localized to the extensor surface of the extremities. EB pruriginosa exhibits extensive clinical heterogeneity with variable expression and delayed age of onset. Mutations in the COL7A1 gene, especially in glycine residues within Gly-X-Y repeats, have been shown to cause this form of DDEB. Here, we report a novel COL7A1 mutation in a Taiwanese pedigree with EB pruriginosa. Using PCR and direct sequence analysis we have identified a G-->T transversion at nucleotide 7097 in exon 92 of COL7A1, converting a glycine residue to valine (G2366V). The mutation resides within a consecutive, uninterrupted stretch of 17 Gly-X-Y residues in the triple-helical domain of type VII collagen. Interestingly, an affected member of this family also displayed elevated IgE levels, previously reported in some patients with this disorder. Our finding further implicates COL7A1 mutation in the pathogenesis of EB pruriginosa and underscores the heterogeneous clinical symptoms of glycine mutations in DDEB.

Epidermólise bolhosa albopapulóide (variante de Pasini)

A epidermólise bolhosa albopapulóide é doença rara, de caráter autossômico dominante, também conhecida como epidermólise bolhosa distrófica albopapulóide de Pasini. Os autores relatam o caso de uma paciente de 37 anos de idade, com início do quadro aos sete anos, com lesões bolhosas e milia nas áreas de traumatismo, além de máculas hipocrômicas e atróficas (lesões albopapulóides) no corpo. A paciente também apresenta pele apergaminhada, xerótica, e distrofia ungueal dos pés. A histopatologia da lesão bolhosa revelou clivagem subepidérmica, compatível com o diagnóstico clínico.

Atopic dermatitis: therapeutic challenge in an infant with dystrophic epidermolysis bullosa

Inherited epidermolysis bullosa (EB) manifests as blisters that usually result from minor trauma. The severity of expression ranges from mild occasional blistering to severe extensive bullae. We report an infant with dystrophic EB worsened by atopic dermatitis (AD). This concomitant skin disease exacerbated EB, because scratching induced bullae and milia. Careful management of AD provided a marked improvement in cutaneous involvement. This report shows that it is important to document and treat inflammatory skin disorders coexisting with EB, because they may influence the overall prognosis of EB.

The clinical spectrum of dystrophic epidermolysis bullosa

BACKGROUND

Dystrophic epidermolysis bullosa (DEB) is a genodermatosis resulting from mutations in COL7A1, the gene encoding type VII collagen. The site and specific nature of the underlying mutation determine the clinical phenotype, which ranges widely from a severe mutilating condition to a relatively mild disorder.

OBJECTIVES

To document the clinical spectrum of DEB within a defined complete population.

METHODS

Since 1992, when compilation of the U.K. epidermolysis bullosa register began, an exhaustive search for DEB sufferers within the Scottish population has been undertaken and their clinical features comprehensively recorded.

RESULTS

One hundred and twenty-eight DEB sufferers have been identified within the Scottish population. In descending order, the frequencies of the different forms of DEB were dominant DEB (DDEB) in 88 individuals (68%), DEB of uncertain inheritance in 24 (19%) and recessive DEB (RDEB) in 16 patients (13%). Within this latter group, nine (7%) had the mutilating Hallopeau-Siemens subtype (RDEB-HS), five (4%) had localized (RDEB-loc) and two (2%) had a predominantly flexural (inverse) form of RDEB. During the study, two patients with RDEB died from squamous cell carcinomas (SCCs), one originating in the skin and the second arising in the oesophagus. Gastrointestinal problems such as dysphagia, constipation and anal fissures, and restriction of mouth opening were experienced by the majority of patients with RDEB and by a significant minority of DDEB sufferers. Pseudosyndactyly was most severe in RDEB-HS, all those over 9 years of age having mitten deformities of the hands. Milder pseudosyndactyly or flexion contractures of the fingers were present in younger patients with this subtype, in most adults suffering from other subtypes of RDEB and in 6% of those with DDEB. External ear involvement, a feature not often reported in DEB, was common in RDEB and also occurred in a minority of those with DDEB. Pruriginous lesions and albopapuloid lesions were each present in both DDEB and RDEB.

CONCLUSIONS

Most patients with DEB have relatively mild dominantly inherited disease, only a minority suffering from severe recessive subtypes. Scarring, gastrointestinal involvement, albopapuloid lesions and a pruriginosa-like pattern each occur in both DDEB and RDEB. With increasing age, SCC is a major cause of morbidity and mortality.

Prurigo nodularis of Hyde: an update

Prurigo nodularis of Hyde is an unusual disorder of unknown aetiology characterized by extremely pruritic nodules with well defined clinical and histopathological aspects. The literature on this disease is reviewed, focusing on the historical background, aetiology, pathogenesis, histopathology and ultrastructure, clinical aspects, differential diagnosis and therapeutic alternatives.

Pretibial dystrophic epidermolysis bullosa: a recessively inherited COL7A1 splice site mutation affecting procollagen VII processing

Pretibial epidermolysis bullosa (PEB) is a rare form of localized epidermolysis bullosa dystrophica (EBD), a heterogeneous group of inherited, blistering diseases characterized by scarring, loss of dermal-epidermal adhesion and altered anchoring fibrils (AF). Mutations in the type VII collagen gene (COL7A1) underlie EBD and in a dominant PEB family a glycine substitution mutation has been identified. We report a 33-year-old man affected by PEB showing abnormal AF and reduced immunostaining for type VII collagen. Mutation search in the COL7A1 gene revealed a 14 bp deletion in the 115 exon-intron boundary (33563del14), which resulted in the in-frame skipping of exon 115 with elimination of 29 amino acids from the pro-alpha1(VII) polypeptide chain. As a consequence, procollagen VII failed to be processed to mature collagen VII and accumulated at the dermal-epidermal junction, as revealed by immunofluorescence staining using a NC-2 domain-specific antibody. The proband's father was a clinically unaffected heterozygous carrier of mutation 33563del14, whereas the maternal pathogenetic mutation has still not been identified. This represents the first report of a recessive deletion mutation in PEB and extends the range of EBD phenotypes associated with mutation 33563del14.

Allelic heterogeneity of dominant and recessive COL7A1 mutations underlying epidermolysis bullosa pruriginosa

The inherited mechanobullous disease, dystrophic epidermolysis bullosa, is caused by type VII collagen gene (COL7A1) mutations. We studied six unrelated patients with a distinct clinical subtype of this disease, epidermolysis bullosa pruriginosa, characterized by pruritus, excoriated prurigo nodules, and skin fragility. Mutation analysis using polymerase chain reaction amplification of genomic DNA, heteroduplex analysis and direct nucleotide sequencing demonstrated pathogenetic COL7A1 mutations in each case. Four patients had a glycine substitution mutation on one COL7A1 allele (G1791E, G2242R, G2369S, and G2713R), a fifth was a compound heterozygote for a splice site mutation (5532 + 1G-to-A) and a single base pair deletion (7786delG), and a sixth patient was heterozygous for an out-of-frame deletion mutation (6863del16). This study shows that the molecular pathology in patients with the distinctive clinical features of epidermolysis bullosa pruriginosa is heterogeneous and suggests that other factors, in addition to the inherent COL7A1 mutation(s), may be responsible for an epidermolysis bullosa pruriginosa phenotype.

Dominant dystrophic epidermolysis bullosa (Pasini) caused by a novel glycine substitution mutation in the type VII collagen gene (COL7A1)

A 12 y old girl with the albopapuloid variant (Pasini) of dominant dystrophic epidermolysis bullosa is studied. The albopapuloid lesions developed within the first year of life, contained milia and were associated with pruritus. Mutation detection of the COL7A1 gene revealed a G-->A transition at nucleotide position 6110 in the mutant allele converting a glycine to glutamic acid (G2037E). This report adds to the expanding database on COL7A1 mutations in dystrophic epidermolysis bullosa.

Three Hong Kong Chinese cases of pretibial epidermolysis bullosa: a genodermatosis that can masquerade as an acquired inflammatory disease

Three patients in two families presented with many years' history of fragile skin, blisters, erosions and scars affecting almost exclusively the shin areas, accompanied by a variable degree of itching. Two of the patients also had toenail dystrophy. Skin biopsy revealed dermal-epidermal blister formation and milia but no immunohistochemical evidence of immunoglobulin or complement deposition. Electron microscopic study of the lesional and perilesional skin showed very sparse or absent anchoring fibrils. Immunolabelling for type VII collagen using LH 7.2 monoclonal antibody revealed a bright, linear staining pattern at the dermal-epidermal junction. The clinicopathological features were thus compatible with pretibial epidermolysis bullosa, a subtype of dystrophic epidermolysis bullosa. Of note, the inflammatory nature of the skin lesions, and their resemblance to nodular prurigo and hypertrophic lichen planus, had caused diagnostic difficulties in all cases in the past. A high degree of awareness of this rare subtype of epidermolysis bullosa is important to establish the correct diagnosis, to allow for genetic counselling and to plan clinical management.

Lichen planoporitis: keratosis lichenoides chronica revisited

We report a 70-year-old woman who over a 7-year period developed a widespread violaceous, reticulate and striate eruption with a keratotic component in a clinical pattern previously described as keratosis lichenoides chronica. Multiple biopsies showed a lichenoid reaction centred over the acrosyringium and eccrine ducts entering the epidermis. The acrosyringeal ducts were surrounded by an epidermis that was associated with saw-tooth acanthosis. The ducts displayed hypergranulosis and keratin plugs that extended into the stratum corneum. In the upper dermis the eccrine ducts showed squamous metaplasia with liquefaction of degeneration of their basal cells as well as apoptotic keratinocytes. The subepidermal acrosyringial zone and the eccrine ducts were associated with lymphocytic inflammation and fibrosis. These histopathological findings may represent the counterpart of lichen planopilaris targeting the eccrine ducts. The clinical features defining keratosis lichenoides chronica probably represents a heterogeneous group of conditions including this distinctive subset of lichen planus which we have termed lichen planoporitis.

Sporadic dystrophic epidermolysis bullosa with concomitant atopic dermatitis

We describe a patient with sporadic dystrophic epidermolysis bullosa associated with well-documented atopic dermatitis. We discuss this case in relation to a newly described clinical subtype of epidermolysis bullosa known as epidermolysis bullosa pruriginosa, a dystrophic variant associated with prominent pruritus. The relations of this case of sporadic dystrophic epidermolysis bullosa with other dominantly inherited forms of dystrophic epidermolysis bullosa such as the Pasini variant, the pretibial variant, and Bart's syndrome are also discussed. The role of atopic dermatitis in exacerbating dystrophic epidermolysis bullosa in this patient raises an important consideration in the care of this group of patients.

A glycine-to-arginine substitution in the triple-helical domain of type VII collagen in a family with dominant dystrophic epidermolysis bullosa pruriginosa

Epidermolysis bullosa pruriginosa is a recently recognized variant of dystrophic epidermolysis bullosa (DEB) characterized by severe pruritus and scarring, mainly involving the extensors of the extremities. In this study, we searched for mutations in the type VII collagen gene (COL7A1) using polymerase chain reaction amplification of exonic segments of COL7A1, followed by heteroduplex analysis, in a Chinese pedigree with dominant DEB displaying a striking anastomosing network of lichenoid papules and scarring. The study revealed a G-to-A transition at nucleotide 6724 within exon 85 of COL7A1, converting a glycine to an arginine (G2242R) within the triple-helical domain of the type VII collagen in affected individuals. These findings demonstrate that EB pruriginosa in this family is a clinical variant of dominant DEB.

Genetic linkage between the collagen type VII gene COL7A1 and pretibial epidermolysis bullosa with lichenoid features

Pretibial epidermolysis bullosa is a rare form of dominant dystrophic epidermolysis bullosa. The disease was diagnosed after considerable delay in a large Belgian family and was remarkable for its late age at onset and its misleading clinical presentation in the proband, which strongly resembled keratosis lichenoides chronica. Both recessively and dominantly inherited forms of dystrophic epidermolysis bullosa have been shown to be linked to the collagen type VII gene, COL7A1. Two-point linkage analysis with two intragenic polymorphisms (PvuII, AluI) in COL7A1 was performed. Strong genetic linkage between the disease in this family and COL7A1 was demonstrated by a lod score of 4.45 (theta = 0) for the AluI polymorphism. The observed intrafamilial variability of clinical phenotypes contradicts the presently proposed classification of dominantly inherited dystrophic epidermolysis bullosa.