Renal agenesis, bilateral

Bilateral renal agenesis (BRA), also known as Potter syndrome or Potter sequence, is a severe congenital condition characterized by the complete absence of both kidneys at birth. This condition arises from a failure of kidney development during embryogenesis. Without functioning kidneys, the fetus cannot produce urine, which is the primary contributor to amniotic fluid during the second and third trimesters of pregnancy. The resulting severe oligohydramnios (critically low amniotic fluid) leads to a cascade of secondary abnormalities collectively known as Potter sequence, including pulmonary hypoplasia (underdeveloped lungs), characteristic facial features (flattened nose, recessed chin, low-set ears), and limb abnormalities due to compression in utero. Bilateral renal agenesis is a lethal condition in the vast majority of cases. Affected infants are typically stillborn or die within hours to days after birth, primarily due to respiratory failure caused by severely underdeveloped lungs. The condition can be detected prenatally through ultrasound, which may reveal absent kidneys and severe oligohydramnios, typically becoming apparent in the second trimester. Additional prenatal findings may include absence of the fetal bladder. The condition affects the urogenital system broadly, and associated anomalies of the genital tract, cardiovascular system, gastrointestinal tract, and musculoskeletal system may also be present. Bilateral renal agenesis can occur as an isolated finding or as part of a broader genetic syndrome. It may arise sporadically or follow an autosomal dominant pattern with incomplete penetrance and variable expressivity, particularly in familial cases linked to mutations in genes such as RET, FGF20, or ITGA8. Some cases are associated with autosomal recessive inheritance. Currently, there is no curative treatment. Management is primarily supportive and palliative. Experimental approaches including serial amnioinfusion during pregnancy and postnatal peritoneal dialysis followed by kidney transplantation have been explored in a very limited number of cases, but these remain investigational and outcomes are uncertain. Genetic counseling is recommended for affected families, as first-degree relatives may carry unilateral renal agenesis or other renal anomalies.

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