Autosomal recessive polycystic kidney disease (ARPKD) was first clinically described in 1946 by E.L. Potter,1 who noted the presence of congenital polycystic kidneys in fetuses, neonates, and infants. More than half a century later, the PKHD1 gene implicated in ARPKD was identified in 2002 through positional cloning studies.2,3 PKHD1 is one of the largest genes in the human genome, located on chromosome 6 with 67 exons, with its longest mRNA transcript being around 16 kB. This gene produces a complex array of alternative transcripts, many of which remain poorly understood.