Kidney–Urinary Tract Involvement in Intermediate Junctional Epidermolysis Bullosa

Kidney-urinary tract (KUT) manifestations cause substantial morbidity in patients with junctional epidermolysis bullosa (JEB), but the spectrum of disease severity and the clinical course have been poorly characterized.To examine in a large cohort of patients with intermediate JEB the KUT manifestations, diagnostic and therapeutic procedures, genotype-phenotype correlations, and outcomes as a basis for recommendations, prognosis, and management.In this retrospective, longitudinal case series study, 99 patients with a diagnosis of JEB based on clinical and genetic findings who were treated in a single dermatology department in Freiburg, Germany, were assessed during an 18-year period (January 1, 2003, to December 31, 2021). Clinical, laboratory, and molecular genetic parameters were extracted from patients' medical records.Clinical characteristics, natural history, management of KUT manifestations, and genotype-phenotype correlations of intermediate JEB.Of the 183 patients with JEB, 99 (54%) had intermediate JEB and were included in this cohort. The cohort included 49 female patients and 50 male patients. None of 49 female patients and 15 of 50 male patients had KUT involvement affecting different levels of the urinary tract, resulting in a prevalence of 30% for males; thus, the overall prevalence was 15%. The mean age at onset of KUT manifestations was 6.9 years (range, first weeks of life to 20 years; age was not available for 1 patient). Median follow-up after diagnosis of KUT involvement was 13 years (range, 3 months to 54 years). Patients with laminin 332 or integrin β4 deficiency had at least 1 missense or splice site genetic variant, leading to residual expression of laminin 332 or integrin α6β4, respectively. Severity of KUT complications did not correlate with the extent of skin involvement but with the affected protein.Physicians and patients with JEB should be aware of the risk for KUT involvement in intermediate JEB, and physicians should apply interdisciplinary and individualized diagnostic and therapeutic procedures for management of these complications. Because this disorder is so rare, multicenter studies are required to make general recommendations.