Table 2. Polycystic kidney disorders with possible prenatal onset.

	ARPKD	ADPKD	HNF1B -related disease	NPHP	TSC2-PKD1 microdeletion
Prevalence	1:20,000	1:500–1:1,000	Not known	1:50,000–1:1,000,000	Not known
Gene(s)	PKHD1	PKD1 , PKD2 GANAB , DNAJB11	HNF1B , deletion 17q12	NPHP1 , INVS , NPHP3 , NPHP4 , IQCB1 , CEP290 , GLIS2 , NEK8 , TMEM67 , TTC21B a , WDR19 , ZNF423 a , CEP164 , ANKS6 , CEP83 , DCDC2 , MAPKBP1	TSC2 , PKD1
Inheritance	AR	AD	AD	AR, AD a	AD
Typical renal ultrasonography findings 19	Bilaterally enlarged kidneys with heterogeneous parenchymal echogenicity with a salt-and-pepper pattern b Other forms of the renal sonographic phenotype are possible: kidney size may range from normal to massively enlarged, hyperechogenicity can be limited by the medulla or diffuse, and cysts can appear as ductal dilatation or as macrocysts of variable size, number, and localization Prenatal US : large hyperechogenic kidneys and oligohydramnios in severe cases	Multiple cortical and medullary cysts. Number of cysts increase with age Possible prenatal presentation with subtle cortical hyperechogenicity and renal enlargement	Variable findings: uni- or bilateral cysts, hypo- or dysplasia, agenesis, or normal kidney imaging The most common cause of kidney hyperechogenicity at prenatal US and of kidney cysts in older children Can mimic ARPKD and other cystic nephropathies	Nonspecific Juvenile NPHP: usually normal-sized or small kidneys and bilaterally increased echogenicity. Cysts are not mandatory for diagnosis. Cysts at the corticomedullary junction are suggestive for NPHP Infantile NPHP : usually enlarged kidneys with cortical microcysts	Kidney phenotype with numerous bilateral large cysts (>2.5 cm) that appear early in life, replace the renal parenchyma, and lead to kidney enlargement
Systemic hypertension	Severe, drug resistant in the first months of life	Before 15 years of life in early manifestation of ADPKD	No data	Not clinically relevant until late stage of the disease	No data
Hepatic fibrosis	100%	Rare	No	As extrarenal manifestation	No
Liver enzymes	Within normal ranges with the exception of GGTP which might be elevated	No data	Elevated	No data	No data
Median age of ESRD onset	1–2 decade of life	58.1 y ( PKD1 ) 79.9 y ( PKD2 )	No data	Significant cause of ESRD <25 y	No data
Extrarenal findings	Sporadically: intracranial or extracranial aneurysms, pancreatic cysts	Polycystic liver disease, pancreatic cysts, seminal vesicle cysts, arachnoid membrane cysts, intra-/extracranial aneurysms, abnormalities of the aorta and cardiac valves, colonic diverticulosis	Abnormalities of the genital tract (vaginal and uterine anomalies), pancreatic anomalies (atrophy, partial agenesis), endocrine/exocrine insufficiency, hypomagnesemia, increase liver enzymes	A broad spectrum of celiopathy-related extrarenal signs may occur (10–20% of patients)	Signs of tuberous sclerosis (e.g., cardiac rhabdomyoma in fetus, hypomelanotic macules, subependymal nodules)

Abbreviations: AD, autosomal dominant inheritance; AR, autosomal recessive inheritance; ARPKD, autosomal recessive polycystic kidney disease; NPHP, nephronophthisis; PKD, polycystic kidney disease; US, ultrasound.

^aNephronophthisis-related genes with possible autosomal dominant inheritance.

^b Salt-and-pepper pattern is typical for ARPKD but may also be seen in other ciliopathies. ²⁰