PKHD1 and autosomal recessive polycystic kidney disease: PKHD1 exhibits a high level of allelic heterogeneity, and more than 300 mutations have been described throughout PKHD1. A clear genotype/phenotype correlation has been described in ARPKD, with two truncating mutations associated with the most severe phenotype, while one or two missense changes are associated with milder disease [39].