Particularly severe kidney manifestations, cystic KHD and KA, were detected in patients with CAKUT carrying the PAX2:c.76dupG variant not degraded by NMD and possibly eliciting a dominant-negative effect compared with patients with a PAX2 nonsense or frameshift variant in exon 3 to 7 with haploinsufficiency as the pathomechanism. This evidence concerns the gene PAX2 and congenital anomaly of kidney and urinary tract.