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Nephronophthisis

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Background

  • Nephronophthisis is an inherited form of progressive kidney disease that affects children. Nephronophthisis is characterized by a progressive destruction of kidney tissue that leads to anemia, which occurs when the level of red blood cells becomes too low; polyuria (frequent urination); polydipsia (excessive thirst); short stature; and eventually kidney failure. If the kidneys fail, waste products accumulate in the blood and the body. As kidney function decreases, symptoms are related to the inability to regulate water and electrolyte balances, to clear waste products from the body, and to promote red blood cell production. Lethargy, weakness, shortness of breath, and generalized swelling may occur.
  • Nephronophthisis, first described in 1951, is sometimes referred to as familial juvenile nephronophthisis (FJN) or autosomal recessive medullary cystic kidney disease. There are at least four types of nephronophthisis, all of which are associated with the production of large amounts of urine and bedwetting early in life. In type 1 (NPH1), kidney failure develops at about age 13. In type 2 (NPH2), kidney failure usually develops from one to three years of age. In type 3 (NPH3), kidney failure develops at about age 19, and in type 4 (NPH4), kidney failure develops in the teenage years. In addition, about 15% of people with nephronophthisis also experience renal-retinal dysplasia (visual impairment caused by degeneration of the retinas). NPH1 is the most commonly documented type, so this monograph focuses on NPH1.
  • NPH1 is caused by a mutation or defect in the NPHP1 gene. This gene provides instructions for making the nephrocystin protein, which is essential for normal kidney functioning. This protein serves as a docking protein that interacts with proteins of adherens junctions, which are protein complexes that occur at cell-to-cell junctions, and focal adhesions, which are large groups of cells that serve as a link between a cell and the cell's external environment. In the case of NPH2, the mutated gene INV encodes for inversin, which is normally closely associated with the cytoskeleton and which allows for cell movement. A mutated INV gene may impair the function of cilia, the structures that allow a cell to move around, thereby contributing to cyst development. For NPH3, there is a genetic mutation in the NPHP3 gene, which encodes the protein nephrocystin-3, whose function is unknown. For NPH4, there is a genetic mutation in the NPHP4 gene, which encodes for the nephroretinin protein, whose function is also unknown. All types of nephronophthisis are inherited, or passed down among family members, as an autosomal recessive trait, meaning that an individual must inherit two copies of the defective gene, one from each parent, for the disease to occur.
  • Nephronophthisis accounts for about 10-20% of chronic kidney failure cases in children and young adults. Both males and females are affected equally, as are all races. It is often discussed with medullary cystic kidney disease, a similar degenerative kidney disease. Both conditions are inherited diseases, with similar renal morphology, characterized by bilateral cysts and end-stage renal disease (ESRD). Medullary cystic kidney disease is a distinct condition inherited as an autosomal dominant trait, and it affects people later in life than nephronophthisis.
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Types of the Disease

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Risk Factors

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Causes

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Signs and Symptoms

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Diagnosis

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Complications

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Treatment

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Integrative Therapies

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Prevention

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Author Information

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References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.