Epidermolisis bullosa (EB): Patogénesis, aspectos clínicos, diagnósticos y genéticos, base molecular, aspectos epidemiológicos, manejo del paciente con EB e implicaciones translacionales del análisis de mutaciones

Abstract

Under the term "Epidermolysis Bullosa" (EB), there is a heterogeneous group of vesicular disorders that are generally congenital and of genetic origin, and affect skin and often mucosas. It is remarkable the extreme fragility of these epithelia; the vesicles arise spontaneously as well as induced by even slight trauma or the influence of high temperatures. Their content is sero-hemorrhagic and in the scarring can be very difficult. As a consecuence of the scarring processes, joint contractures and fusion of digits (pseudo-syndactyly) can occur. Pathogenetically, EB is caused by abnormal blistering at the basement membrane zone in the dermal-epidermal attachment zone and its surroundings. This is due to alterations in the attachment complexes, and some mutations have been identified in a total of 10 genes expressed in such level. Four main types of EB can be distinguished (simple, junctional, dystrophic and hemidesmosomal), depending on the level at which the cleavage that forms the bulla takes place, although about 30 subtypes have been described. The clinical characteristics or optic microscopy are not adequate for diagnosis, and it is mandatory to perform electron microscopy, immunofluorescent and immunohistochemical studies, as well as mutation analysis if available. Regarding the epidemiological aspects, in the Spanish Collaborative Study of Congenital Malformations (ECEMC), since 1976 up to December 2004, a total of 2,204,264 liveborn infants were controlled and, among them 27 cases have been identified, for a minimum frequency of 0.12 per 10,000 (95% confidence interval:0.08-0.18). It seems generally accepted that the determination of the frequency of EB is subject to multiple biases and registration of cases is always incomplete. We have also reviewed the issues related to management of EB patients by clinicians.