Introduction-
Renal tubular dysgenesis is a severe disorder observed in developing fetuses. It can be an inherited disorder or may be acquired during fetal development. The kidney structures, particularly the proximal tubules, are underdeveloped in this condition. It results in various health risks, and the fetus fails to survive. The affected fetuses usually die before birth or are stillborn. The following article gives insight into renal tubular dysgenesis.
What Is Renal Tubular Dysgenesis?
Renal tubular dysgenesis is a severe disorder in which the proximal tubules of the kidneys are absent or underdeveloped. It is a congenital disorder that affects the fetuses of both genders. It is characterized by early onset and persistent anuria (absence of urine production), which results in oligohydramnios (decreased amniotic fluid volume) and Potters syndrome, and ossification defects. It can be acquired during development or inherited as an autosomal recessive disorder. Renal tubular dysgenesis is also referred to as autosomal recessive renal tubular dysgenesis and Allanson Pantzar McLeod syndrome.
What Are the Causes of Renal Tubular Dysgenesis?
Renal tubular dysgenesis can be due to genetic or acquired causes. It includes the following:
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Genetic Causes: These include mutations in the genes that are associated with the renin-angiotensin systems, such as ACE, AGT, AGTR1, or REN genes. These genes regulate blood pressure and the fluid and salt homeostasis in the body. It plays a vital role in renal development in the developing fetus. Mutations in these genes disrupt the production or function of angiotensin II and cause dysfunction of the renin-angiotensin system. This results in low blood pressure and reduced blood flow. As a result of hypoperfusion, the fetal tissues lack oxygen supply during development. Hence, renal development is impaired, and renal tubular dysgenesis occurs. Hypoperfusion also causes ossification defects in the skull. Renal tubular dysgenesis is inherited as an autosomal recessive disorder.
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Acquired Causes: These include maternal exposure to medications like angiotensin-converting enzyme (ACE) inhibitors to regulate blood pressure and non-steroidal anti-inflammatory agents (NSAIDs) and conditions that cause hypoperfusion during fetal development, such as fetal renal artery stenosis (narrowing), fetal renal vein thrombosis, cardiac problems, congenital hemochromatosis (deposition of iron at harmful levels), hypoplastic calvaria, trisomy 21, cranial hypoplasia (decreased cerebellar volume), medullary ray nodules, and complications like twin-to-twin transfusion syndrome (both fetuses share a common placenta resulting in disproportionate blood flow to one of the fetuses) in twin pregnancies.
What Are the Effects of Renal Tubular Dysgenesis?
The proximal tubules are essential for the reabsorption of nutrients, water, and other materials into the blood and for the excretion of waste products into the urine. If the proximal tubules are absent or nonfunctional, urine cannot be produced. This results in anuria. Fetal urine is the essential component of the amniotic fluid surrounding the fetus. Anuria results in oligohydramnios. Amniotic fluid protects the fetus, and it is essential for the development of organs, including the lungs. Oligohydramnios results in Potter’s syndrome. Renal tubular dysgenesis causes various abnormalities, and the affected fetus fails to survive. The affected fetus dies before birth, is stillborn, or dies soon after birth due to respiratory failure.
What Are the Signs and Symptoms Associated With Renal Tubular Dysgenesis?
The signs and symptoms are observed during fetal development. It includes the following:
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Fetal urine output is reduced (anuria), resulting in oligohydramnios, a condition in which amniotic fluid is reduced. This reduces the cushioning effect on the fetus and also disrupts organ development.
Signs and symptoms observed during fetal development include the following:
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Anuria.
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Oligohydramnios.
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Underdeveloped kidneys.
Signs and symptoms observed after birth include the following:
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Symptoms of Potter’s syndrome are observed as a result of oligohydramnios. It presents with typical facial features such as a flattened nose, large and low-set ears, the presence of large spaces between skull bones due to ossification defect, clubfeet, excess skin, and abnormal lung development.
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Anuria (lack of urine production).
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Low blood pressure.
What Are the Complications Associated With Renal Tubular Dysgenesis?
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Ossification defects in the skull.
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Low blood pressure and hypoperfusion.
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Kidney dysfunction.
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Breathing difficulties, respiratory failure.
How Is Renal Tubular Dysgenesis Diagnosed?
The diagnosis of renal tubular dysgenesis depends on the following:
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Prenatal Ultrasound Scans: These can help in detecting abnormal levels of amniotic fluid. The abnormalities in the fetal kidneys and defects in the skull can be detected.
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Genetic Testing: It is performed to confirm the diagnosis of renal tubular dysgenesis.
How Is Renal Tubular Dysgenesis Treated?
Fetuses with renal tubular dysgenesis do not survive and die before birth. Some fetuses are stillborn or die soon after birth. If the fetus survives after birth, the following treatment options are recommended:
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Fresh frozen plasma infusion is performed to improve and maintain blood pressure.
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Peritoneal dialysis is required to remove the waste products.
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Respiratory assistance is required to improve breathing in the newborn baby.
There is no specific treatment protocol for renal tubular dysgenesis. It is mainly aimed at supportive management.
Can Renal Tubular Dysgenesis Be Prevented?
There are no specific guidelines to prevent the occurrence of renal tubular dysgenesis. Genetic testing and prenatal ultrasound scans can help to detect the presence of renal tubular dysgenesis. Genetic counseling is essential if there is a family history of such abnormalities. A pregnant mother with high blood pressure should not consume renin-angiotensin blockers to prevent renal tubular dysgenesis in the fetus.
What to Expect With Renal Tubular Dysgenesis?
Renal tubular dysgenesis is a severe disorder, and the prognosis is poor. Most fetuses die during gestation, and 26 to 30 percent of the neonates are stillborn or die soon after birth. In rare cases, the affected baby survives into childhood. There are reports of children with this disorder who have survived over two years of age.
Conclusion
Renal tubular dysgenesis is a severe disorder observed in developing fetuses. The kidney structures, particularly the proximal tubules, are underdeveloped in this condition. It results in various health risks, and the fetus fails to survive. Prenatal scanning and genetic testing can help in determining this disorder. If the fetus survives this condition, supportive therapy is given.
