Differential Expression of Pyloric Atresia in Junctional Epidermolysis Bullosa with ITGB4 Mutations Suggests that Pyloric Atresia is due to Factors Other than the Mutations and Not Predictive of a Poor Outcome: Three Novel Mutations and a Review of the Literature

Abstract

Junctional epidermolysis bullosa with pyloric atresia (JEB-PA) is an autosomal recessive blistering disease including lethal and non-lethal variants due to mutations in ITGB4 and ITGA6. It is unclear whether PA is caused directly by the mutations in these genes or by other factors. Skin biopsies from patients with JEB were processed for immunofluorescence mapping. When staining for integrin beta4 or alpha6 was absent or reduced, ITGB4 was screened for mutations. A review of known mutations of ITGB4 and the phenotypes of patients with JEB-PA was undertaken. Three novel ITGB4 mutations were identified in 3 families with JEB-PA: 2 splice-site and one insertion mutation. Two families with lethal phenotypes (EB-050 and EB-049) were due to combinations of premature termination codons and missense mutations (658delC/R252C and 3903dupC/G273D, respectively). The third family EB-013 has 2 JEB affected siblings; a brother with PA and a sister without PA. Both were homo notzygous for ITGB4 264G>A/3111-1G>A. Two cases had no gastrointestinal symptoms or signs of PA. PA is an inconstant feature of the subtype of epidermolysis bullosa known as JEB-PA. It is most likely that multiple factors influence the development of PA and its presence is not predictive of a poor outcome. It is possible that institutions that do not routinely screen immunofluore notscence mapping for integrin alpha6beta4 staining in the absence of PA are missing this form of epidermolysis bullosa.