Variation of COL7A1 gene in dystrophic epidermolysis bullosa pruriginosa / 中华医学遗传学杂志

OBJECTIVE@#To perform gene mutation analysis in a Chinese pedigree with dystrophic epidermolysis bullosa pruriginosa (DEB-Pr), and explore phetotype, genotype, and genotypes-phenotypes relationship of DEB-Pr.@*METHODS@#Potential variants of the COL7A1 gene were detected by skin targeted sequencing panel and verified by Sanger sequencing. The pathogenicity of the variation was analyzed.@*RESULTS@#Compound heterozygous variants, c.4128delT and c.8234G>A, were detected in the COL7A1 gene of the two patients. The c.4128delT(p.Pro1376fs) variant was derived from their mother and unreported previously. According to the American College of Medical Genetics and Genomics Standards and Guidelines, it was suggested to be a pathogenic mutation. The c.8234G>A(p.Arg2745Gln) variant was derived from their father, and possibly is a pathogenic variation.@*CONCLUSION@#In this study, the compound heterozygous variants of c.4128delT(p.Pro1376fs) and c.8234G>A(p.Arg2745Gln) of the COL7A1 gene probably underlies the disease in this patient and his sister. And our study expands the database on mutations of DEB-Pr.

Inherited epidermolysis bullosa: update on the clinical and genetic aspects

Abstract Inherited epidermolysis bullosa is a group of genetic diseases characterized by skin fragility and blistering on the skin and mucous membranes in response to minimal trauma. Epidermolysis bullosa is clinically and genetically very heterogeneous, being classified into four main types according to the layer of skin in which blistering occurs: epidermolysis bullosa simplex (intraepidermal), junctional epidermolysis bullosa (within the lamina lucida of the basement membrane), dystrophic epidermolysis bullosa (below the basement membrane), and Kindler epidermolysis bullosa (mixed skin cleavage pattern). Furthermore, epidermolysis bullosa is stratified into several subtypes, which consider the clinical characteristics, the distribution of the blisters, and the severity of cutaneous and extracutaneous signs. Pathogenic variants in at least 16 genes that encode proteins essential for the integrity and adhesion of skin layers have already been associated with different subtypes of epidermolysis bullosa. The marked heterogeneity of the disease, which includes phenotypes with a broad spectrum of severity and many causal genes, hinders its classification and diagnosis. For this reason, dermatologists and geneticists regularly review and update the classification criteria. This review aimed to update the state of the art on inherited epidermolysis bullosa, with a special focus on the associated clinical and genetic aspects, presenting data from the most recent reclassification consensus, published in 2020.

Reproductive alternatives for patients with dystrophic epidermolysis bullosa / Opções reprodutivas para pacientes com epidermólise bolhosa distrófica

ABSTRACT Epidermolysis bullosa describes a group of skin conditions caused by mutations in genes encoding proteins related to dermal-epidermal adhesion. In the United States, 50 cases of epidermolysis bullosa per 1 million live births are estimated, 92% of which classified as simplex, 5% dystrophic, 1% junctional and 2% non-classified. Dystrophic epidermolysis bullosa is associated with autosomal, dominant and recessive inheritance. Epidermolysis bullosa causes severe psychological, economic and social impacts, and there is currently no curative therapy, only symptom control. Embryonic selection is available for epidermolysis bullosa patients in order to prevent perpetuation of the condition in their offspring.

RESUMO O termo "epidermólise bolhosa" descreve um grupo de afecções cutâneas causadas por mutações em genes que codificam proteínas relacionadas à aderência dermoepidérmica. Nos Estados Unidos, estima-se a ocorrência de 50 casos de epidermólise bolhosa por 1 milhão de nascidos vivos, sendo 92% deles da forma simples, 5% da forma distrófica, 1% da forma juncional e 2% não classificados. A epidermólise bolhosa do tipo distrófica foi associada a padrões autossômicos, dominante e recessivo. A epidermólise bolhosa causa sérios impactos psicológicos, econômicos e sociais, e não há tratamento curativo atualmente − apenas controle dos sintomas. A seleção embrionária é disponível para portadores de epidermólise bolhosa, a fim de evitar a perpetuação da condição em seus descendentes.

Scanning electron microscopy of a blister roof in dystrophic epidermolysis bullosa / Microscopia eletronica de varredura do teto de uma bolha de epidermolise bolhosa distrofica

In dystrophic epidermolysis bullosa the genetic defect of anchoring fibrils leads to cleavage beneath the basement membrane, with its consequent loss. We performed scanning electron microscopy of an inverted blister roof of a case of dystrophic epidermolysis bullosa, confirmed by immunomapping and gene sequencing. With a magnification of 2000 times a net attached to the blister roof could be easily identified. This net was composed of intertwined flat fibers. With higher magnifications, different fiber sizes could be observed, some thin fibers measuring around 80 nm and thicker ones measuring between 200 and 300 nm.

Na epidermólise bolhosa distrófica, o defeito genético das fibrilas ancorantes leva à clivagem abaixo da membrana basal, com sua consequente perda. Realizamos microscopia eletrônica de varredura do teto invertido de uma bolha de um caso de epidermólise bolhosa distrófica, cujo diagnóstico foi confirmado com imunomapeamento e com sequenciamento gênico. Com uma ampliação de 2.000 vezes, pôde ser facilmente identificada uma rede ligada ao teto da bolha. Essa rede era composta por fibras achatadas e entrelaçadas. Com grandes aumentos, fibras de diferentes tamanhos puderam ser observadas: algumas finas, medindo cerca de 80 nm, e outras mais largas, medindo entre 200 nm e 300 nm.

Clinical variability in dystrophic epidermolysis bullosa and findings with scanning electron microscopy / Variabilidade clínica em epidermólise bolhosa distrófica e achados de microscopia eletrônica de varredura

In dystrophic epidermolysis bullosa, the genetic defect of anchoring fibrils leads to cleavage beneath the basement membrane and its consequent loss. A 46 year-old female patient presented blisters with a pretibial distribution associated with nail dystrophy. Her two children had hyponychia and anonychia, which affected all toe nails and the thumb, forefinger and middle finger. DNA sequencing identified in exon 75 of COL7A1 gene a pathologic mutation: c.6235G>A (p.Gly2079Arg). Immunomapping of a blister demonstrated collagen IV (basal membrane) in the blister roof and collagen VII in its floor, confirming dystrophic epidermolysis bullosa. Scanning electron microscopy of an inverted blister showed net-forming collagen attached to the blister roof . The variability found in this family has already been reported and confirms, on a clinical basis, the nail subtype as a dystrophic variant.

Na epidermólise bolhosa distrófica, o defeito genético das fibrilas de ancoragem leva à clivagem abaixo da membrana basal com sua consequente perda. Uma paciente de 46 anos apresentava bolhas pré-tibiais associadas à distrofia ungueal. Seus dois filhos apresentavam hipo e anoníquia, afetando todas as unhas dos pododáctilos e dos primeiros, segundos e terceiros quirodáctilos. O sequenciamento de DNA identificou no exon 75 do gene COL7A1 uma mutação patológica: c.6235G>A (p.Gly2079Arg). O imunomapeamento identificou o colágeno IV no teto e colágeno VII no assoalho de uma bolha , confirmando o diagnóstico de epidermólise bolhosa distrófica. A microscopia eletrônica de varredura de um teto invertido de bolha demonstrou rede de colágeno aderida ao mesmo. A variabilidade clínica encontrada nessa família já foi escrita e confirma, que o subtipo ungueal das epidermólises bolhosas é uma forma distrófica.

Type VII Collagen Gene Mutations (c.8569G>T and c.4879G>A) Result in the Moderately Severe Phenotype of Recessive Dystrophic Epidermolysis Bullosa in a Korean Patient

Dystrophic epidermolysis bullosa (DEB) are caused by mutations in the COL7A1 gene, which encodes type VII collagen. Even though more than 500 different COL7A1 mutations have been identified in DEB, it still remains to be under-investigated. To investigate the mutation of COL7A1 in moderately severe phenotype of recessive DEB (RDEB) in a Korean patient, the mutation detection strategy was consisted of polymerase chain reaction (PCR) amplification of genomic DNA, followed by heteroduplex analysis, nucleotide sequencing of the PCR products demonstrating altered mobility. In this study, we found that one mutation (c.8569G>T) was detected within exon 116. The mutation of c.8569G>T in exon 116 changed the GAG (Glu) to TAG, eventually resulted in premature termination of type VII collagen polypeptide. Furthermore the mother did not have the mutation c.8569G>T in exon 116. The other novel mutation (c.4879G>A) was detected within exon 51 of both patient and mother, thereby resulting in changing valine (Val) to isoleucine (Ile) in type VII collagen polypeptide. Taken together, in this study we identified compound heterozygosity for COL7A1 mutations (c.8569G>T and c.4879G>A) in moderately severe RDEB in a Korean patient. We hope that this data contribute to the expanding database on COL7A1 mutations in DEB.

Epidermolysis bullosa pruriginosa: a rare autosomal dominant variant.

A 35 years female presented with extremely pruritic, violaceous, small vesiculopapular lesions over both shins since 11/12 years of age. The intensity of pruritus slightly descreased following oozing of fluid. History of similar incidence in her mother and maternal grandfather was present. There was no toe-nail dystrophy. Histopathology report showed the lesions had hyperkeratotic, mild acanthosis, dermal lymphohistiocytic infiltrate and subepidermal cleft. The case was diagnosed to be a case of epidermolysis bullosa pruriginosa.

Las epidermolisis bullosas distróficas en México: 2470insG representa la mutación mas común en 21 familias / 2470insG, represents the commonest mutation in Mexican patients with dystrophic bullous epidermolysis: a study of 21 families

Antecedentes: Las epidermolisis ampollosas congénitas son enfermedades caracterizadas por ampollas en piel y mucosas al mínimo traumatismo. Son tres tipos: simple, unión y distrófica. Las epidermolisis ampollosas distróficas (EAD) son causadas por mutaciones en el gen COL 7Al que codifica la producción del colágeno tipo VII localizado en las fibrillas de anclaje de la unión dermoepidérmica. Objetivo: Determinar las bases moleculares de las EAD en México. Material y métodos: se analizaron ADN de 21 familias mexicanas con EAD. Se realizó reacción en cadena de la polimerasa, estudios de heteroduplex secuenciación de nucleótidos en ADN de los pacientes. Resultados: Se detectó 59 de 67 mutaciones en 36 pacientes. Se encontraron seis mutaciones de tipo codón de terminación prematuro, substitución de glicina, remoción de intrones de novo y depleción interna. La mutación comúnmente más encontrada fue la 2470insG, en 21 (58.35%) de 36 pacientes. Conclusiones: En pacientes con EAD, la mutación 2470insG es la más frecuente en México. Recomendamos analizar esta mutación a Mexicanos con EAD como primera opción. Estos resultados son útiles para clasificar los subtipos de EAD, dar asesoramiento genético, así como para entender un poco más la fisiopatología de esta enfermedad mecano ampollosa.

BACKGROUND: Type VII collagen gene (COL 7 Al) mutations are the cause of dystrophic epidermolysis bullosa (DEB), but most mutations are specific to individual families and there is limited data on the nature of COL 7 Al mutations in certain ethnic populations. OBJECTIVE: To determine the molecular basis of DEB in Mexican patients and describe the most frequent mutation among this ethnic population. METHODS: Most subjects were approached at FUNDACION DEBRA MEXICO AC. Molecular analysis was performed by polymerase chain reaction (PCR) of genomic DNA using COL 7 A l-specific primers, heteroduplex analysis, and direct nucleotide sequencing. RESULTS: Fifty nine of 67 COL 7 Al possible mutations (88%) were identified; 36 individuals (31 recessive, five dominant) from 21 families. Recessive mutations included six frameshift mutations, four silent glycine substitutions and two splice site mutations. CONCLUSIONS: The present study informs a different kind of mutation observed in our patient population. Only two mutations informed in this study had been described earlier among another ethnic group. The most frequent mutation was 2470insG, affecting 21 (58.3%) out of 36 patients with DEB. These new data will be helpful in facilitating the accurate diagnosis of an DEB subtype, and will add further insight into the pathophysiology of this mechanobullous disease.

Novedades moleculares y clínicas de las colágenas / New molecular and clinical aspects of collagens

La colágena es una de las proteínas más abundantes del organismo. Junto con los otros componentes de la matriz extracelular (glucoproteínas no colagenosas, proteoglicanos, lamininas, fibronectinas, tromboespondinas, enectina y tenascina) promueve la adhesión celular, activa vías de señales intracelulares, y regula las actividades de varios factores de crecimiento y de otas proteínas. Durante los últimos 20 años se han identificado por lo menos 19 tipos de colágenas genéticamente diferentes, codificadas por más de 30 genes. En esta primera parte revisamos algunos aspectos novedosos sobre colágenas fibrilares, las formadoras de láminas, las que forman estructuras tipo abalorio, y las multiplexinas. Cuando fue posible correlacionamos las anormalidades de estas proteínas colagenosas con la enfermedad resultante