Nephropathic Cystinosis
What is Nephropathic Cystinosis?
Nephropathic cystinosis is an inherited error of metabolism affecting about 500 people in the United States. A genetic mutation disables the mechanism for clearing the amino acid cystine, a breakdown product of cellular proteins. This results in an accumulation of cystine crystals in all organs and tissues.
The condition is usually diagnosed in early childhood when patients exhibit poor growth, vision problems (photophobia) and specific kidney problems (called Fanconi syndrome) that result in increased urination, thirst, and dehydration. If left untreated, cystinosis destroys major organ systems including the kidneys, eyes, liver, muscles, pancreas and the brain. Additional complications include muscle wasting, poor growth, difficulty swallowing, diabetes and hypothyroidism.
Current Standard of Care
Studies have shown that cysteamine therapy may delay and/or prevent kidney transplant and other clinical manifestations of the disease.1,2,3,4 The goal of cysteamine treatment of cystinosis is to reduce cystine levels in cells. However, patient compliance is challenging due to frequent dosing and gastrointestinal side effects.2,4,5,6
Research and Development for Cystinosis Patients
Raptor is developing a delayed-release formulation of cysteamine, DR Cysteamine. DR Cysteamine is designed to potentially reduce the dose frequency and gastrointestinal side effects that have typically been associated with cysteamine therapy.
In addition to Raptor's efforts, a clinical study of cysteamine eyedrops is underway to address the build-up of cystine crystals in the eyes of cystinosis patients. This study is currently recruiting patients. Learn more about the ongoing clinical trial.
Meanwhile, dedicated researchers are seeking a cure for cystinosis. Much of this research is supported by grants from not-for-profit foundations such as the Cystinosis Research Foundation and Cystinosis Research Network.
Additional Resources
- The Cystinosis Foundation
- The Cystinosis Research Foundation
- The Cystinosis Research Network
- University of California, San Diego, Biochemical Genetics
- National Center for Biotechnology Information
- Cystinosis—Genetic Home Reference
- NIH List of Cystinosis Studies
References:
- Gahl WA, Balog JZ, Kleta R. Nephropathic cystinosis in adults: natural history and effects of oral cysteamine therapy. Annals of Internal Medicine. 2007;147:242-250.
- Levtchenko EN, van Dael CM, de Graaf-Hess AC, Wilmer MJ, van den Heuvel LP, Monnens LA, Blom HJ. Strict cysteamine dose regimen is required to prevent nocturnal cystine accumulation in cystinosis. Pediatr Nephrol. 2006;21:110–113.
- Markello TC, Bernardini IM, Gahl WA. Improved renal function in children with cystinosis treated with cysteamine. N Engl J Med. 1993;328:1157-1162.
- Kleta RK, Bernadini IM, Ueda M, Varade WS, Phornphutkul C, Krasnewich D, Gahl WA. Long-term follow-up of well-treated nephropathic cystinosis patients. J Pediatr. 2004; 145:555-60.
- Kleta R, Gahl WA. Pharmacological treatment of nephropathic cystinosis with cysteamine. Expert Opin. Pharmacother. 2004;5(11):2255-2262.
- http://www.fda.gov/medwatch/SAFETY/2007/Jun_PI/Cystagon_PI.pdf