Cystinosis

Cystinosis, sometimes referred to as amine diabetes, is a Cystinspeicherkrankheit based on a disturbance of the transport of cystine the lysosomes. The sparingly soluble cystine is stored mainly in the reticuloendothelial cells of various organs. Particularly affected are hereby cornea, conjunctiva, liver, spleen, lymph nodes and bone marrow. While the Cystinspeicherung in these organs usually caused no significant clinical symptoms, it comes in the kidney to serious malfunctioning. Synonymous terms are rarely used Abderhalden - Fanconi syndrome for occurring in childhood form of the disease and Bürki - Rohner Cogan 's syndrome for adults form.

Occurrence and development of disease

There are three forms of the disease after their course. The infantile nephropathic cystinosis or the most common form. It is based on a defect in the CTNS gene on chromosome 17 that encodes the lysosomal membrane protein Cystinosin. Cystinosin is responsible for the transport of cystine in the lysosome. The disease is inherited as an autosomal recessive trait and occurs in one in 200,000 births. Likewise, an adolescent form with onset in adolescence and adult form can be distinguished. The exact causes of the latter two forms have not yet been clarified.

Symptoms

After the first symptom-free months of life the disease with nonspecific constitutional symptoms such as anorexia, vomiting, chronic constipation, weight arrest, unexplained fever, dystrophy, polydipsia, polyuria and a vitamin D -refractory rickets begins. Intellectual development is not affected, at least with light blond and light- shy patients usually. With a slit-lamp examination many glowing cystine crystals in the cornea and conjunctiva can be detected. By the damaged kidneys it comes to water and electrolyte losses (primarily hypokalemia) and acidification of the blood ( = acidosis). Especially in the course of infection may result in infants and young children to serious metabolic imbalance and weakness. In addition, there may be spontaneous fractures and so-called pseudo fractures. The Cystinosis occurs in many progressive forms. Thus, there are also cases in which the first symptoms until 10 - 12 years occur (benign form), but the scenario is much faster, so that these young people soon have kidney damage and other symptoms. The adult form is found only in adults, then crystal deposits are mostly in the eyes of the only symptom.

Laboratory diagnostics

Proving is the quantitative detection of intracellular and Cystinvermehrung in peripheral lymphocytes, skin fibroblasts and from a Amnionzellkultur ( prenatal diagnosis ).

Therapy

This is yet symptomatic, however, contributes significantly to the life extension in good general condition with. Electrolyte and pH shifts need to be monitored and corrected if necessary. Rickets is treated with high doses of vitamins. A cystinentspeichernde therapy is done with cysteamine, in tablet form for the body and in drop or ointment to the eyes. In uremic final hemodialysis and, optionally, a kidney transplant is needed.