RT-qPCR confirmed that ARPKD URECs express lower levels of total PKHD1 (70%, as assessed using primers that do not differentiate among different splicing isoforms around exon 43) and lower levels (40%) of transcript A, containing a full-length exon 43, compared to the average abundance in the two unrelated controls (Fig. 2d, Additional Figure 5a). Here, PKHD1 is linked to autosomal recessive polycystic kidney disease.