Potter Syndrome

Potter syndrome, also known as Potter sequence, is a rare disorder that an infant is born with when there is a lack of amniotic fluid, the clear liquid that surrounds the fetus, during pregnancy (i.e., in utero). Amniotic fluid supports, cushions, and protects the developing fetus in the uterus. Without this fluid, the pressure on the developing fetus can cause the fetus’s skeletal and respiratory systems to develop atypically. 

Potter syndrome is generally caused by problems in the development of the fetus’s kidneys, which typically produce most of the amniotic fluid.

Potter syndrome is classified into several subtypes depending on the underlying cause, including classic Potter syndrome, type I, type II, type III, and type IV. Classic Potter syndrome, which is the most common type, results from bilateral renal agenesis, or the absence of both kidneys. Type I, on the other hand, is associated with autosomal recessive polycystic kidney disease, in which multiple cysts form within the kidneys and affect their function. Type II is due to kidney abnormalities that result from early kidney development in the uterus. Type III results from autosomal dominant polycystic kidney disease, which is similar to, but distinct from, the autosomal recessive polycystic kidney disease that causes type I. Finally, type IV is related to obstructive uropathy, or a blockage in the fetus’s urinary tract. 

Moreover, Potter syndrome can sometimes be caused by other pathologies. Occasionally, Potter syndrome can result from an undetected, early rupture of the amniotic membranes and subsequent, gradual leakage of amniotic fluid. Potter syndrome is also associated with Prune belly syndrome, in which deformities of the fetus’s abdominal muscles affect the development of the renal system. 

In rare instances, Potter syndrome can occur sporadically with no known associated cause. 

While Potter syndrome itself is not genetic, the underlying cause may be genetic in some cases. For example, polycystic kidney disease, which is a genetic condition that can be inherited either in an autosomal dominant or an autosomal recessive pattern, can cause Potter syndrome. Autosomal dominant polycystic kidney disease requires only one copy of the altered gene to be inherited from either parent in order for the condition to impact the fetus, whereas autosomal recessive polycystic kidney disease requires two copies of the affected gene, one from each parent, in order for Potter syndrome to develop. 

Additionally, mutations in the FGF20 gene on chromosome 8 and the GREB1L gene on chromosome 18 can also be inherited in an autosomal recessive manner and stop one or both kidneys from forming (i.e., renal agenesis), which is associated with classic Potter syndrome. 

Regardless, even though the aforementioned conditions can be inherited in a genetic manner, they can also occur spontaneously without any family history.

The diagnosis of Potter syndrome begins with a thorough review of medical history and physical examination of both the pregnant person and the fetus. During the examination, the use of abdominal or transvaginal ultrasound imaging is necessary for identifying the syndrome. Using sound waves, an ultrasound will produce an image of the developing fetus and allow the clinician to visualize certain structures, such as the fetal kidneys, as well as the amount of amniotic fluid present. 

If ultrasound findings are inconclusive, additional imaging, such as magnetic resonance imaging (MRI), may also be helpful in defining renal malformations. In cases with minimal amniotic fluid, better visualization may require amnioinfusion, the injection of additional fluid inside the amniotic cavity. If other chromosomal abnormalities are suspected, amniocentesis, in which amniotic fluid is taken from the uterus for testing, could offer valuable information for the diagnosis. However, this procedure can be extremely difficult and dangerous for the fetus, especially if the amount of amniotic fluid is already low.

If Potter syndrome is not detected before birth, different indications may lead to the diagnosis. Primarily, atypically low urine production for a newborn and the characteristic physical features described above are often indicative of Potter syndrome. Healthcare providers may also perform blood tests to assess electrolyte abnormalities, such as high sodium (i.e., hypernatremia) and potassium (i.e., hyperkalemia) concentrations in the blood, as well as low levels of calcium (i.e., hypocalcemia) and metabolic acidosis resulting from renal failure. Additionally, the infant’s serum creatinine levels may be assessed to determine renal function. An X-ray showing that the newborn’s lungs are underdeveloped may also indicate Potter syndrome. 

Potter syndrome, also known as Potter sequence, is a rare congenital disorder associated with a lack of amniotic fluid during pregnancy. In addition to impaired skeletal and respiratory development, characteristic physical features of infants with Potter syndrome, called Potter facies, include wrinkly skin, low-set ears, flat nose and chin, and widely separated eyes with epicanthal folds. Potter syndrome is often caused by various problems in the development of the kidneys, early rupture of membranes, or other rare congenital disorders. Diagnosis is primarily based on imaging, such as ultrasound and MRI scans, as well as blood tests. Treatment depends on the underlying cause and is available only for the few infants who survive gestation and birth, as Potter syndrome is terminal in most cases.