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Renal tubular dysgenesis
A rare disorder of the fetus characterized by absent or poorly developed proximal tubules of the kidneys, persistent oligohydramnios, leading to Potter sequence (facial dysmorphism with large and flat, low-set ears, lung hypoplasia, arthrogryposis and limb positioning defects), and skull ossification defects.
ORPHA:3033Classification level: Disorder
The incidence of renal tubular dysgenesis is unknown.
The clinical picture is of early onset oligohydramnios, skull ossification defects and neonatal pulmonary and renal failure.
Non-syndromic renal tubular dysgenesis can be acquired during fetal development due to drugs taken by the mother (such as in utero exposure to ACE inhibitors) or in the context of twin-twin transfusion syndrome (TTTS). The genetic form is due to biallelic pathogenic variations in genes encoding either angiotensinogen (AGT; 1q42.2), renin (REN; 1q32.1), angiotensin converting enzyme (ACE ; 17q23.3) or angiotensin 2 receptor type 1(AGTR1; Xq23). Other disorders that can feature renal tubular dysgenesis include severe fetal cardiopathy, congenital hemochromatosis, and severe fetal renal artery stenosis.
The diagnosis is based on renal histology with or without proximal tubule labeling, and molecular genetics.
The differential diagnosis includes secondary forms of renal tubular dysgenesis and leakage of amniotic fluid.
Diagnosis may be suspected on routine prenatal ultrasound by presentation of oligohydramnios in the presence of a normal kidney scan. In families with an antecedence, genetic prenatal diagnosis is possible where the pathogenic variations have been previously identified.
For the genetic form, transmission is autosomal recessive. Genetic counseling should be offered to at-risk couples (both individuals are carriers of a disease-causing mutation) informing them that there is a 25% risk of having an affected child at each pregnancy.
Management and treatment
Management is typically expectant. Severe pulmonary hypoplasia is not treatable. Few cases with less severe respiratory disease were treated with peritoneal dialysis, followed by renal transplantation when the weight was sufficient. In cases due to twin-to-twin transfusion, fetoscopic laser photocoagulation, amnioreduction or delivery be suggested.
The prognosis is extremely severe in the majority of cases.
A summary on this disease is available in Deutsch (2021) Español (2021) Français (2021) Nederlands (2021) Português (2021) Italiano (2012) Japanese (2021, pdf)