Renal tubular dysgenesis

Renal tubular dysgenesis (RTD) is a rare and severe disorder of kidney development characterized by the absence or poor development of the proximal tubules of the kidneys. This condition leads to a marked reduction or complete absence of urine production (oligohydramnios or anhydramnios) during fetal life, which in turn causes the Potter sequence — a constellation of features including pulmonary hypoplasia (underdeveloped lungs), limb contractures, and a characteristic flattened facial appearance resulting from compression due to insufficient amniotic fluid. Skull ossification defects are also frequently observed. The condition primarily affects the renal and pulmonary systems and is almost invariably fatal in the perinatal period due to respiratory failure and refractory hypotension. RTD can occur in both genetic (autosomal recessive) and acquired forms. The genetic form is caused by mutations in genes encoding components of the renin-angiotensin system (RAS), including AGT (angiotensinogen), REN (renin), ACE (angiotensin-converting enzyme), and AGTR1 (angiotensin II receptor type 1). These mutations result in a complete loss of function of the renin-angiotensin system, which is critical for normal renal tubular development and fetal blood pressure regulation. An acquired form of RTD can also occur in fetuses exposed to medications that inhibit the renin-angiotensin system, such as ACE inhibitors or angiotensin receptor blockers taken by the mother during pregnancy, or in the context of twin-to-twin transfusion syndrome. Currently, there is no curative treatment for the genetic form of renal tubular dysgenesis. Management is primarily supportive and palliative. Prenatal diagnosis is possible through ultrasound detection of oligohydramnios and molecular genetic testing when a familial mutation is known. Genetic counseling is essential for affected families, particularly given the autosomal recessive inheritance pattern and the 25% recurrence risk in subsequent pregnancies. Prevention of the acquired form involves avoiding RAS-inhibiting medications during pregnancy.

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