Autosomal recessive polycystic kidney disease (ARPKD)-lessons learned from the international ARPKD registry study ARegPKD

Autosomal recessive polycystic kidney disease (ARPKD) is rare but is one of the most important causes of kidney failure in childhood and adolescence. ARPKD is characterized by obligatory hepatorenal involvement and pronounced phenotypic variability. In most cases, it is caused by variants in the PKHD1 gene encoding the ciliary protein fibrocystin. The treatment of ARPKD is purely symptomatic. Targeted therapy has not yet been established. The prediction of clinical courses remains difficult in ARPKD. As ARPKD occurs significantly less frequently than autosomal dominant polycystic kidney disease (ADPKD), clinical or radiological risk markers for kidney disease progression could not be established for ARPKD in a similar manner. Genotype-phenotype correlations cannot fully explain the differences in the clinical courses. Clinical research in the field of ARPKD faces a number of challenges, such as rarity of the disease, complex disease courses, late, atypical or liver-predominant manifestations as well as incomplete understanding of the molecular pathogenesis. An exact longitudinal phenotypic characterization of large numbers of patients in international collaborations is helpful for the establishment of clinical, radiological and laboratory risk markers that are the basis for evaluation of first treatment options. In this setting, the European registry study ARegPKD was established. This article presents the evolution of the ARegPKD and extracts of lessons learned.