Cystinosis

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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: nephropathic cystinosis, intermediate cystinosis, and non-nephropathic or ocular cystinosis. Infants affected by nephropathic cystinosis initially exhibit poor growth and particular kidney problems (sometimes called renal Fanconi syndrome). The kidney problems lead to the loss of important minerals, salts, fluids, and other nutrients. The loss of nutrients not only impairs growth, but 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 age two years, 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 age 10 years. Other signs and symptoms that may occur in untreated patients 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 begins to affect individuals from age 12 years to age 15 years. 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 do not usually experience growth impairment or kidney malfunction. 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?

Mutations in the CTNS gene cause 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 saclike structures called lysosomes, which digest, process, and sort cellular components. 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 two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

Source: National Institutes of Health

New duodenal ulcer research from Keio University, Department of Surgery outlined

"Male Wistar rats were divided into a saline group (n=15) and a Candida group (n=17). Cysteamine-HCl (Sigma; 31 mg/100 g) was administered thrice on day 1 to both groups of animals. Candida albicans at a density of 10⁸ in 0.5 mL of saline was administered 1 h before, and 12 h and 24 h after the first administration of cysteamine in the Candida group. Perforated duodenal ulcers were observed in 94.1% of the rats in the Candida group, but only 26.7% of the rats in the saline group (p <0.01). The area of the duodenal ulcers in the Candida group was 40.89 ±33.07 mm2, whereas that in the saline group was 16.53 ±20.4 mm2 (p <0.05). The mortality rate was significantly higher in the Candida group than in the saline group. In the Candida group, colonization by C. albicans was recognized at the ulcer base, surrounded by marked granulocytic infiltration. The number of eosinophils infiltrating the ulcer base was also significantly greater in the Candida group than in the saline group. Immunohistochemical analysis revealed the expression of secretory aspartyl protease (SAP) in the region of the ulcer showing colonization by C. albicans in the Candida group. Candida albicans aggravates duodenal ulcer perforation in the experimental model of cysteamine-induced duodenal ulcer perforation," wrote T. Nakamura and colleagues, Keio University, Department of Surgery.

The researchers concluded: "The present findings suggest that SAP and host-parasite relationships, including granulocyte-dependent mechanisms, may be involved in the aggravation of ulcer perforation by C. albicans."

Nakamura and colleagues published their study in the Journal of Gastroenterology and Hepatology (Candida albicans aggravates duodenal ulcer perforation induced by administration of cysteamine in rats. Journal of Gastroenterology and Hepatology, 2007;22(5):749-56).

For additional information, contact T. Nakamura, Keio University School of Medicine, Dept. of Surgery, Tokyo, Japan.

Publisher contact information for the Journal of Gastroenterology and Hepatology is: Blackwell Publishing Asia, 54 University St., PO Box 378, Carlton, Victoria 3053, Australia.

Keywords: Japan, Tokyo, Cysteamine, Duodenal Ulcer, Experimental Model, Gastroenterology, Hepatology, Nephropathic Cystinosis Therapy, Radiation-Protective Agent.

This article was prepared by Biotech Business Week editors from staff and other reports. Copyright 2007, Biotech Business Week via NewsRx.com.