Cystinosis

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Classification according to ICD-10
E72.0 Disorders of the amino acid
transport cystinosis
ICD-10 online (WHO version 2019)

The cystinosis or cystinosis , sometimes referred to as amine diabetes called, is a Cystinspeicherkrankheit that on a transport disturbance of cystine from the lysosome is based. The poorly soluble cystine is mainly stored in reticuloendothelial cells of various organs. The cornea , conjunctiva , liver , spleen , lymph nodes and bone marrow are particularly affected . While the cystine storage in the organs mentioned usually does not cause any significant clinical symptoms, severe functional disorders occur in the kidneys.

Seldom used synonymous terms are Lignac syndrome , Abderhalden-Fanconi syndrome for the form of the disease occurring in childhood and Bürki-Rohner-Cogan syndrome for the adult form.

Occurrence and development of the disease

A distinction is made between three forms of the disease according to their course. Infantile or nephropathic cystinosis is the most common form. It is based on a defect in the CTNS gene on chromosome 17, which codes for the lysosomal membrane protein cystinosine. Cystinosine is responsible for transporting cystine out of the lysosome. The condition is inherited as an autosomal recessive trait and occurs in 1 in 200,000 births. A distinction is also made between an adolescent form with the onset of the disease in adolescence and an adult form. The exact causes of the latter two forms have not yet been clarified.

Symptoms

After the first symptom-free months of life, the disease begins with unspecific general symptoms such as loss of appetite, vomiting, chronic constipation, weight arrest, unclear fever, dystrophy , polydipsia , polyuria and vitamin D-refractory rickets . The intellectual development of the mostly light-blond and light-shy patients is usually not influenced. With a slit lamp examination , many light-scattering cystine crystals can be detected in the cornea and conjunctiva. The damaged kidneys lead to water and electrolyte losses (especially hypokalemia ) and acidification of the blood (= acidosis ). Especially in the course of infections, this can lead to severe metabolic imbalances and weakness in babies and toddlers . In addition, there may be spontaneous fractures come and so-called pseudo-fractures. Cystinosis occurs in many different forms. There are also cases in which the first symptoms do not appear until the 10th to 12th year of life (benign form), but the course is much faster, so that these adolescents also soon have kidney damage and other symptoms. The adult form is only discovered in adults, then crystal deposits in the eyes are usually the only symptom.

Laboratory diagnostics

Evidence is provided by the quantitative evidence of an intracellular cystine increase in peripheral lymphocytes , skin fibroblasts and from an amniotic cell culture ( prenatal diagnosis ).

therapy

This has so far been symptomatic, but contributes significantly to extending life in a good general condition. Shifts in electrolytes and pH values ​​must be observed and corrected if necessary. Rickets is treated with high doses of vitamins. A cystine-storing therapy takes place with cysteamine , in tablet form for the body and in drop or ointment form for the eyes. There are now successor drugs called Cystagon, and the latest Procysbi. Medicines are taken every 6 hours, or now more likely every 12 hours, so that at least the night's rest is guaranteed. In uremic final state is a hemodialysis and possibly a kidney transplant needed.

literature

  • JP Schadé: Lexicon of Medicine and Health. MedicaPress, 2003, p. 99.

Individual evidence

  1. ↑ John W. Foreman: Fanconi Syndrome and other Proximal Tubule Disorders. In: Jürgen Floege, Richard J. Johnson, John Feehally: Comprehensive Clinical Nephrology. 4th edition. St. Louis 2010, pp. 586f.

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