Cystinosis

Reviewed February 2008

What is cystinosis?

Cystinosis is a condition in which the body accumulates the amino acid cystine (a building block of proteins) within cells. Excess cystine forms crystals that can build up and damage cells. These crystals negatively affect many systems in the body, especially the kidneys and eyes.

There are three distinct types of cystinosis. In order of decreasing severity, they are nephropathic cystinosis, intermediate cystinosis, and non-nephropathic or ocular cystinosis. Infants affected by nephropathic cystinosis initially exhibit poor growth and a particular type of kidney damage (renal Fanconi syndrome) that causes the kidneys to eliminate certain molecules that should be reabsorbed into the bloodstream. The kidney problems lead to the loss of important minerals, salts, fluids, and other nutrients. The loss of nutrients impairs growth and may result in soft, bowed bones (hypophosphatemic rickets), especially in the legs. The nutrient imbalances in the body lead to increased urination, thirst, dehydration, and abnormally acidic blood (acidosis). By about the age of 2, cystine crystals may be present in the clear covering of the eye (cornea). The buildup of these crystals in the eye causes an increased sensitivity to light (photophobia). Untreated children will experience complete kidney failure by about the age of 10. Other signs and symptoms that may occur in untreated people, especially after adolescence, include muscle deterioration, blindness, inability to swallow, diabetes, and thyroid and nervous system problems.

The signs and symptoms of intermediate cystinosis are the same as nephropathic cystinosis, but they occur at a later age. Intermediate cystinosis typically becomes apparent in affected individuals in adolescence. Malfunctioning kidneys and corneal crystals are the main initial features of this disorder. If intermediate cystinosis is left untreated, complete kidney failure will occur, but usually not until the late teens to mid-twenties.

People with non-nephropathic or ocular cystinosis usually do not experience growth impairment or kidney malfunction. In most cases, the only symptom is photophobia due to cystine crystals in the cornea.

How common is cystinosis?

Cystinosis affects approximately 1 in 100,000 to 200,000 newborns. The incidence is higher in the province of Brittany, France, where the disorder affects 1 in 26,000 individuals.

What genes are related to cystinosis?

All three types of cystinosis are caused by mutations in the CTNS gene. Mutations in this gene lead to a deficiency of a transporter protein called cystinosin. Within cells, this protein normally moves cystine out of the lysosomes, which are compartments in the cell that digest and recycle materials. When cystinosin is defective or missing, cystine accumulates and crystallizes in the lysosomes. The buildup of cystine crystals damages cells in the kidneys and eyes and may also affect other organs.

How do people inherit cystinosis?

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 treatment for cystinosis?

You may find information on treatment or management of cystinosis or some of its symptoms in the links below, particularly the links for Gene Reviews, MedlinePlus Encyclopedia, Educational resources, and Patient support.

Where can I find additional information about cystinosis?

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

MedlinePlus - Health information
- Encyclopedia: Fanconi syndrome (http://www.nlm.nih.gov/medlineplus/ency/article/000333.htm)
- Encyclopedia: Photophobia (http://www.nlm.nih.gov/medlineplus/ency/article/003041.htm)
- Health Topic: Kidney Diseases (http://www.nlm.nih.gov/medlineplus/kidneydiseases.html)
Educational resources - Information pages
- Genetics Education Center University of Kansas Medical Center (http://www.kumc.edu/gec/support/cystinos.html)
- Madisons Foundation (http://www.madisonsfoundation.org/index.php/component/option,com_mpower/diseaseID,268/)
- Orphanet (http://www.orpha.net//consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=213)
Patient support - For patients and families
- Children Living with Inherited Metabolic Diseases (CLIMB) (UK) (http://www.CLIMB.org.uk)
- Cystinosis Research Network (http://www.cystinosis.org/)
- National Organization for Rare Disorders (http://www.rarediseases.org/search/rdbdetail_abstract.html?disname=Cystinosis)
- The Cystinosis Foundation (http://www.cystinosisfoundation.org/)
- The Cystinosis Research Foundation (http://www.natalieswish.com/)

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

Gene Reviews - Clinical summary (http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=ctns)
Gene Tests - DNA tests ordered by healthcare professionals (http://www.genetests.org/query?testid=3377)
ClinicalTrials.gov - Linking patients to medical research (http://clinicaltrials.gov/search/condition=%22cystinosis%22)
PubMed - Recent literature (http://www.ncbi.nlm.nih.gov/pubmed?term=(Cystinosis[MAJR])+AND+(cystinosis[TIAB])+AND+english[la]+AND+human[mh]+AND+"last+1080+days"[dp])
Online Books - Medical and science texts
- Scriver's Online Metabolic and Molecular Bases of Inherited Disease (OMMBID): Cystinosis: A Disorder of Lysosomal Membrane Transport (http://books.mcgraw-hill.com/getommbid.php?isbn=0071459960&template=ommbid&c=199)
- Scriver's Online Metabolic and Molecular Bases of Inherited Disease (OMMBID): The Renal Fanconi Syndrome (http://books.mcgraw-hill.com/getommbid.php?isbn=0071459960&template=ommbid&c=196)
OMIM - Genetic disorder catalog
- OMIM topic: Cystinosis, late-onset juvenile or adolescent nephropathic (http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=219900)
- OMIM topic: Cystinosis, nephropathic (http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=219800)
- OMIM topic: Cystinosis, ocular nonnephropathic (http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=219750)

What other names do people use for cystinosis?

Cystine storage disease
Cystinoses

See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What if I still have specific questions about cystinosis?

See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.
Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).
Submit your question to Ask the Geneticist (http://www.askthegen.org/).

What glossary definitions help with understanding cystinosis?

acidosis ; acids ; amino acid ; autosomal ; autosomal recessive ; cell ; cornea ; cystine ; deficiency ; dehydration ; diabetes ; Fanconi syndrome ; gene ; incidence ; kidney ; lysosome ; mineral ; molecule ; mutation ; nervous system ; photophobia ; protein ; recessive ; renal ; rickets ; sensitivity ; sign ; symptom ; syndrome ; thyroid

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://ghr.nlm.nih.gov/glossary).

References

Delgado G, Schatz A, Nichols S, Appelbaum M, Trauner D. Behavioral profiles of children with infantile nephropathic cystinosis. Dev Med Child Neurol. 2005 Jun;47(6):403-7. (http://www.ncbi.nlm.nih.gov/pubmed/15938069?dopt=Abstract)
Gahl WA, Thoene JG, Schneider JA. Cystinosis. N Engl J Med. 2002 Jul 11;347(2):111-21. Review. No abstract available. (http://www.ncbi.nlm.nih.gov/pubmed/12110740?dopt=Abstract)
Kalatzis V, Antignac C. New aspects of the pathogenesis of cystinosis. Pediatr Nephrol. 2003 Mar;18(3):207-15. Epub 2003 Feb 27. Review. (http://www.ncbi.nlm.nih.gov/pubmed/12644911?dopt=Abstract)
Kleta R, Gahl WA. Cystinosis: antibodies and healthy bodies. J Am Soc Nephrol. 2002 Aug;13(8):2189-91. Review. No abstract available. (http://www.ncbi.nlm.nih.gov/pubmed/12138155?dopt=Abstract)
Kleta R, Gahl WA. Pharmacological treatment of nephropathic cystinosis with cysteamine. Expert Opin Pharmacother. 2004 Nov;5(11):2255-62. Review. (http://www.ncbi.nlm.nih.gov/pubmed/15500372?dopt=Abstract)
Kleta R, Kaskel F, Dohil R, Goodyer P, Guay-Woodford LM, Harms E, Ingelfinger JR, Koch VH, Langman CB, Leonard MB, Mannon RB, Sarwal M, Schneider JA, Skovby F, Sonies BC, Thoene JG, Trauner DA, Gahl WA; NIH Office of Rare Diseases. First NIH/Office of Rare Diseases Conference on Cystinosis: past, present, and future. Pediatr Nephrol. 2005 Apr;20(4):452-4. Epub 2005 Jan 27. Review. No abstract available. (http://www.ncbi.nlm.nih.gov/pubmed/15747161?dopt=Abstract)
Nesterova G, Gahl W. Nephropathic cystinosis: late complications of a multisystemic disease. Pediatr Nephrol. 2007 Nov 16; [Epub ahead of print]. (http://www.ncbi.nlm.nih.gov/pubmed/18008091?dopt=Abstract)
Servais A, Morinière V, Grünfeld JP, Noël LH, Goujon JM, Chadefaux-Vekemans B, Antignac C. Late-onset nephropathic cystinosis: clinical presentation, outcome, and genotyping. Clin J Am Soc Nephrol. 2008 Jan;3(1):27-35. (http://www.ncbi.nlm.nih.gov/pubmed/18178779?dopt=Abstract)
Sonies BC, Almajid P, Kleta R, Bernardini I, Gahl WA. Swallowing dysfunction in 101 patients with nephropathic cystinosis: benefit of long-term cysteamine therapy. Medicine (Baltimore). 2005 May;84(3):137-46. (http://www.ncbi.nlm.nih.gov/pubmed/15879904?dopt=Abstract)
Tsilou E, Zhou M, Gahl W, Sieving PC, Chan CC. Ophthalmic manifestations and histopathology of infantile nephropathic cystinosis: report of a case and review of the literature. Surv Ophthalmol. 2007 Jan-Feb;52(1):97-105. Review. (http://www.ncbi.nlm.nih.gov/pubmed/17212992?dopt=Abstract)

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? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.



	http://ghr.nlm.nih.gov/ A service of the U.S. National Library of Medicine®