1. Table I. Nonsyndromic human CAKUT (Part 1)
Type of Cause Anatomical and histological Gene
malformation characteristics
Renal agenesis No interaction between Absence of the ureter and kidney Ret, GDNF
the UB and MM
Renal hypoplasia Aberrant interactions Reduced number of UB branches and Pax2, Sall1
among the UB, MM nephrons that are fully formed Six2, BMP4
or stroma Small kidney size HNF1β
UMOD
Renal dysplasia Aberrant inteactions Reduced number of UB branches and Pax2
among the UB, MM nephrons. Presence of undifferentiated HNF1β
or stroma stromal and mesenchymal cells, cysts or UMOD
cartilage. Frequently associated with Nphp1
kidney hypoplasia BMP4, Six2
XPNPEP3
Polycystic Aberrant tubular and Cysts in tubules and collecting ducts Pkd1, Pkd2
kidneys collecting duct patterning Normally formed glomeruli HNF1β
NPHP1
Multicystic Aberrant interactions Absence of glomeruli and tubules HNF1β
dysplastic among the UB, MM or Presence of large size cysts UPIIIA
kidneys stroma Poorly formed atretic ureters
Aberrant patterning Small remnant kidney (if organ
involutes

2. Table I. Nonsyndromic human CAKUT (Part 2)
Type of Cause Anatomical and histological Gene
malformation characteristics
Medullary Aberrant tubular and Tubular atrophy, interstitial fibrosis, UMOD
cystic kidney collecting duct patterning cysts in distal tubules and
disease medullary collecting ducts
Duplex Supernumerary UB Duplex ureters and kidneys or Robo2
ureters budding from the ND duplex ureters and collecting FoxC1, FoxC2
systems BMP4
May be associated with VUR or
obstruction if UB budding is ectopic
Horseshoe Defects in renal capsule Kidneys are fused at inferior lobes HNF1β
kidney Failed migration and located lower than usual
VUR Ectopic UB budding from Movement of urine from the bladder Robo2
the ND or insertion into into the ureter or kidney Slit2
the bladder Can be due to urethral atresia or PUV Pax2
Can be associated with dysplastic UMOD
Kidneys
PUV Retention of the remnants Folds of posterior urethra in males ACE, AT1R
of the urogenital membrane Associated with bilateral VUR,
hydroureter, hydronephrosis,
dysplastic kidneys