Renal Dysplasia, Bilateral

Bilateral renal dysplasia is a form of renal dysplasia (RD; see this term), a renal tract malformation in which the development of both kidneys is abnormal and incomplete. Bilateral RD can be segmental, and of variable severity, with renal aplasia corresponding to extreme RD.

Epidemiology

The prevalence of bilateral renal dysplasia is unknown.

Clinical description

The classic antenatal presentation of renal dysplasia is of either large or small bright kidneys, with or without cystic spaces at the routine 20-week scan. Extreme bilateral RD may limit renal function to such an extent that oligohydramnios occurs with the Potter sequence (lung hypoplasia, severe renal failure, wide-set eyes, flattened nose, receding chin, large and low-set ears deficient in cartilage). Neonates born with the Potter sequence will die shortly after birth. Patients with some residual renal function may develop hypertension, proteinuria and renal failure during childhood.

Etiology

The etiology of RD is unknown. RD can be part of a syndrome, such as Kallmann syndrome, Bardet-Biedl syndrome, Beckwith-Wiedemann syndrome, diGeorge syndrome, Fraser syndrome, renal coloboma syndrome, and renal cysts and diabetes syndrome (see these terms). HNF1B (17q12), PAX2 (10q24.3-q25.1) and uroplakins genes, which are associated with some of these syndromes, may have an important role in the pathogenesis of RD. Renal dysplasia can also be found in cases of urine obstruction in utero, such as posterior urethral valves, vesicoureteral reflux (see these terms), or pelviureteric junction obstruction. Whether the dysplasia is a parallel presentation of these congenital anomalies, or a consequence of the high urine pressure, remains to be determined.