Potter syndrome

The features of Potter syndrome may be evident during the prenatal period and may include a history of oligohydramnios or ultrasonography which reveals cysts within the kidneys. During the neonatal period, there may be an absence or minimal amounts of urine output or respiratory distress. Physical findings may include 'Potter facies', which consists of a flattened nose, recessed chin, epicanthal folds, and low-set abnormal ears; pulmonary hypoplasia (underdevelopment of the lungs); skeletal malformations such as hemivertebrae (wedge-shaped spinal bones), sacral agenesis (absence of all or part of the sacrum, the lowest section of the spine) and limb anomalies; ophthalmologic malformations; and cardiovascular malformations.^[1]  

More detailed information about these findings can be accessed through the eMedicine web site.

A sequence of events causes the features of Potter syndrome. After approximately 16 weeks gestation, the amount of amniotic fluid present mainly depends on fetal urine production. In normal fetal development, the fetus continuously swallows amniotic fluid, which then gets reabsorbed by the GI tract and then reintroduced into the amniotic sac by the kidneys. Oligohydramnios (too little of amniotic fluid) occurs if the volume of amniotic fluid is less than normal for that period of gestation. This may be due to decreased urine production caused by bilateral renal agenesis, obstruction of the urinary tract, or, occasionally, prolonged rupture of membranes. The resulting oligohydramnios is the cause of the abnormalities seen in Potter syndrome. The mechanism of lung hypoplasia (underdevelopment) in this condition is not clear, but it is believed that adequate space for fetal movement and the movement of amniotic fluid into the fetal lungs is required for the normal development of lungs.^[1]

In one study that looked at 80 cases of Potter syndrome, the authors stated that the abnormal renal findings leading to oligohydramnios were bilateral renal agenesis in 21.25%; cystic dysplasia in 47.5%; obstructive uropathy in 25%; and others in 5.25%.^[2]

Potter syndrome itself is not inherited, because the name refers to a group of common features that can result from oligohydramnios, regardless of the primary cause of the oligohydramnios. In many individuals, the underlying cause of the renal failure/abnormality is undetermined. However, the primary cause is genetic and/or inherited in some cases. Genetic abnormalities which may cause developmental abnormalities leading to Potter syndrome may include:

• autosomal recessive polycystic kidney disease
• autosomal dominant polycystic kidney disease (rare in neonates)
• hereditary renal adysplasia (agenesis or dysplasia) , which may be due to mutations in the RET gene, UPK3A gene, or another gene; may be autosomal dominant.^[3]
• other genetic syndromes in which the development of the kidney is often affected; for a list of syndromes associated with renal hypoplasia/dysgenesis click here.
• chromosome abnormalities (some of which may be inherited); for a list of chromosome abnormalities associated with renal agenesis click here.