The PCR products from different colonies separated into 4 different molecular weight bands on gel electrophoresis (623 bp, 499 bp, 452 bp and 368 bp) (Additional Figure 3a), indicating the presence of 4 different splicing isoforms of PKHD1 around exon 43, in both control and ARPKD URECs. This evidence concerns the gene PKHD1 and autosomal recessive polycystic kidney disease.