LAUSR

Considering the fact that the IgA vasculitis (IgAV), formerly known as Henoch-Schönlein purpura, is the most common systemic vasculitis in childhood, with an incidence fluctuating from 3 to 27 cases per 100 000 children [1, 2], it would be expected that there are uniform guidelines for diagnosis and treatment of this clinical entity and that we know a lot about the etiopathogenesis of the disease. However, everyday clinical practice confronts us with many unanswered questions and dilemmas concerning IgAV disease severity, duration of the autoimmune process, optimal treatment choices, and prognosis, and all of them arise from insufficient knowledge of the mechanisms of disease development. The main attribute of IgAV is palpable purpura which affects the lower extremities and buttocks [3]. Because in most cases the disease is self-limiting and has an excellent prognosis, these patients usually receive attention when complications occur, both acute, which are predominantly related to gastrointestinal system, and chronic, among which the most important is kidney involvement [4, 5]. Given that nephritis (IgAVN) occurs in 20 to 60% of children with IgAV [1, 4], of whom 1.6 to 15% may develop kidney failure [6, 7], this disease is of interest to nephrologists. These data also warn us that the disease should not be underestimated and that it does not always have to be benign. Therefore, we readwith special interest a series of articles by Koskela et al., published in this and previous editions of Pediatric Nephrology, which relate to aspects of the genetic basis of the disease, issues associated with different histological classifications of IgAVN, and selection of appropriate therapy [8–11]. With these papers, the authors nicely concluded the topic of IgAV while also pointing out the most important unresolved issues related to the disease. The latest article by Koskela et al. is a genome-wide association study (GWAS) in children with IgAV. Although this is neither the first nor the largest study in which GWAS is applied in the same target patient population [12], it brings novelties in the sense that a larger number of patients with IgAVN is included, and it is innovative in that the population of patients with IgAV is not only compared with the general reference population but also with patients with inflammatory bowel disease (IBD). The most important result that emerges from the above study is that haplotype DQA1*01:01/ DQB1*05:01/DRB1*01:01 is associated with susceptibility to IgAV but not with other autoimmune diseases.