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Genetics Home Reference: Nephronophthisis

09/30/2014 11:30 PM EDT

Source: National Library of Medicine - NIH

Nephronophthisis

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Reviewed September 2014

What is nephronophthisis?

Nephronophthisis is a disorder that affects the kidneys. It is characterized by inflammation and scarring (fibrosis) that impairs kidney function. These abnormalities lead to increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). In addition, affected individuals develop fluid-filled cysts in the kidneys, usually in an area known as the corticomedullary region. Another feature of nephronophthisis is a shortage of red blood cells, a condition known as anemia.

Nephronophthisis eventually leads to end-stage renal disease (ESRD), a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively. Nephronophthisis can be classified by the approximate age at which ESRD begins: around age 1 (infantile), around age 13 (juvenile), and around age 19 (adolescent).

About 85 percent of all cases of nephronophthisis are isolated, which means they occur without other signs and symptoms. Some people with nephronophthisis have additional features, which can include liver fibrosis, heart abnormalities, or mirror image reversal of the position of one or more organs inside the body (situs inversus).

Nephronophthisis can occur as part of separate syndromes that affect other areas of the body; these are often referred to as nephronophthisis-associated ciliopathies. For example, Senior-Løken syndrome is characterized by the combination of nephronophthisis and a breakdown of the light-sensitive tissue at the back of the eye (retinal degeneration); Joubert syndrome affects many parts of the body, causing neurological problems and other features, which can include nephronophthisis.

Read more about Senior-Løken syndrome and Joubert syndrome.

How common is nephronophthisis?

Nephronophthisis is found in populations worldwide. It occurs in an estimated 1 in 50,000 newborns in Canada, 1 in 100,000 in Finland, and 1 in 922,000 in the United States. Its incidence in other populations is unknown. Nephronophthisis is the most common genetic cause of ESRD in children and young adults.

What genes are related to nephronophthisis?

Nephronophthisis has several genetic causes, which are used to split the condition into distinct types. Nephronophthisis type 1, which is the most common type of the disorder and one cause of juvenile nephronophthisis, results from changes affecting the NPHP1 gene. The proteins produced fromNPHP1 and the other genes involved in nephronophthisis are known or suspected to play roles in cell structures called cilia. Cilia are microscopic, finger-like projections that stick out from the surface of cells and are involved in chemical signaling. Cilia are important for the structure and function of many types of cells and tissues, including cells in the kidneys, liver, and brain and the light-sensitive tissue at the back of the eye (the retina).

The genetic mutations involved in nephronophthisis are thought to impair the structure or function of cilia in some way, which likely disrupts important chemical signaling pathways during development. Although researchers believe that defective cilia lead to the features of nephronophthisis, the mechanism remains unclear. It is unknown why some people with mutations in nephronophthisis-associated genes have only kidney problems, while others develop additional signs and symptoms.

How do people inherit nephronophthisis?

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Where can I find information about diagnosis or management of nephronophthisis?

These resources address the diagnosis or management of nephronophthisis and may include treatment providers.

You might also find information on the diagnosis or management of nephronophthisis in Educational resources and Patient support.

General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.

To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.

Where can I find additional information about nephronophthisis?

You may find the following resources about nephronophthisis helpful. These materials are written for the general public.

MedlinePlus - Health information (5 links)
Educational resources - Information pages (3 links)
Patient support - For patients and families (3 links)

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

Genetic Testing Registry - Repository of genetic test information (13 links)
ClinicalTrials.gov - Linking patients to medical research
OMIM - Genetic disorder catalog (13 links)

What other names do people use for nephronophthisis?

NPH
NPHP

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines and How are genetic conditions and genes named? in the Handbook.

What if I still have specific questions about nephronophthisis?

Ask the Genetic and Rare Diseases Information Center

Where can I find general information about genetic conditions?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding nephronophthisis?

adolescent ; anemia ; autosomal ; autosomal recessive ; breakdown ; cell ; cysts ; end-stage renal disease ; ESRD ; fibrosis ; gene ; incidence ; inflammation ; inherited ; juvenile ; kidney ;neurological ; polydipsia ; polyuria ; recessive ; renal ; renal disease ; retina ; situs inversus ; stage ;syndrome ; tissue

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

References (5 links)

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.