Cystinosis is the name given to a hereditary metabolic disease. It involves excessive accumulation of cystine in numerous organs.
What is cystinosis?
Cystinosis is a congenital metabolic disorder that is inherited. It is also known as cystinosis, cystine storage disease, amine diabetes, Abderhalden-Fanconi syndrome, or Lignac syndrome. In most cases, the disease manifests in childhood. There is also an adult form called Bürki-Rohner-Cogan syndrome. Typical features of cystinosis include accumulation of the amino acid cystine in several organs. These may be the muscles, kidneys, pancreas, eyes, as well as the brain. At different ages, it comes to attack different organs. Cystinosis is considered a very rare disease. It occurs in only one in 100,000 to 200,000 newborn children. In the whole world, only about 200,000 cases of the disease have been registered so far.
Causes
In cystinosis, it is important to differentiate between three forms of progression. Thus, there is an infantile-nephropathic, an adolescent-nephropathic, and an adult-benign form.
- The most common form is formed by the infantile-nephropathic variant. In this case, malfunctions of the kidneys occur in the affected child already at the age of six months.
- The adolescent nephropathic form, on the other hand, shows up only in adolescence.
- The adult-benign form occurs only in adults.
Cystinosis belongs to the group of hereditary diseases. It is inherited autosomal recessive. This means an inheritance on two autosomes. In addition, two genes are required from both the father and the mother. In each parent whose child has cystinosis, there is one normal gene and one defective gene. In the parents, cystinosis is not noticeable. A mutation of the CTNS gene is responsible for the development of cystinosis. This gene encodes cystinosin, which is a lysosomal cystine transporter. The transport disorder in the cystine lysosomes results in the accumulation of cystine in several organs. These are primarily the liver, spleen, kidneys, bone marrow, and the conjunctiva and cornea of the eyes (cornea). Since cystine is only slightly soluble, the amino acid causes crystals to form within the cell lysosomes. This probably leads to the destruction of the cells.
Symptoms, complaints, and signs
The symptoms of cystinosis depend on the particular form of progression. The infantile nephropathic form usually occurs between 6 and 18 months of age. It is characterized by general symptoms such as fever, vomiting, loss of appetite, weight loss and chronic constipation. In addition, polyuria (increased urine excretion), polydipsia (abnormal thirst), malgrowth and rickets occur. The disease usually has no effect on the intellectual development of affected children. Since the kidneys are affected by cystine storage disease, this leads to the loss of water and electrolytes as well as to acidosis (blood acidification). If infections are added to this, the affected babies and toddlers often suffer from lack of strength and considerable metabolic derailments. Spontaneous bone fractures and pseudofractures are also possible. In the adolescent nephropathic form of progression, cystinosis does not become apparent until between the ages of 10 and 12. The disease then progresses more rapidly, resulting in rapid kidney damage. The adult-benign form cannot be detected until adulthood. The only symptom in adults is usually deposits of crystals in the eyes.
Diagnosis and course
Because cystinosis is an extremely rare disease, its diagnosis is not always easy. However, it is possible to detect cystine deposition in the lymph nodes, rectal mucosa, fibroblasts, and leukocytes (white blood cells). If the eyes are examined with a slit lamp, cystine crystals can be detected in the cornea. If the back of the eye is mirrored, retinopathy can be seen. Prenatal diagnosis can also be performed in families at risk for cystinosis. This involves a chorionic biopsy between the 8th and 9th week of pregnancy.An amniocentesis can also be performed between the 14th and 16th week of pregnancy. Without special treatment, cystinosis results in fatal kidney failure in affected children. As a rule, they lose their kidney function by the age of 9. If a kidney transplant is performed, the new kidney will not be damaged in adulthood. However, without treatment with cysteamine, there is a risk of significant complications such as diabetes mellitus, dysphagia, and muscle loss, although this does not occur in every case.
When should you see a doctor?
If cystinosis is suspected, a physician should be consulted immediately. Depending on the form of progression, the disease manifests itself with different symptoms. In the infantile-neprhopathic form, the typical symptoms – including fever, vomiting, loss of appetite, weight retention, and chronic constipation – usually appear between the ages of 6 and 18 months. Parents who notice corresponding symptoms during this period should take their child to the family doctor immediately. Similar symptoms, which however only appear between the 10th and 12th year of life, indicate the adolescent nephropathic form. In this case, too, the rule is to go directly to the pediatrician and arrange for the child to be examined. In adulthood, the disease is usually manifested only by conspicuous deposits of crystals in the eyes. A specific diagnosis is therefore difficult. A visit to the doctor is recommended if a gradual decline in quality of life is felt for which no clear cause can be found. Anyone who already suffers from another metabolic disease should immediately talk to the responsible physician if symptoms are mentioned.
Treatment and therapy
It is not yet possible to treat the causes of cystinosis. Therefore, treatment is limited to the symptoms of the disease. For this purpose, affected children receive phosphate and vitamin D. In this way, rickets can be avoided. Also important is the intake of cysteamine, which serves to slow down kidney damage. Thus, the drug inhibits the deposition of cystine in the cells. Cysteamine also has a positive effect on the growth of children with the disease. The drug is usually administered in the form of capsules. To treat cystine deposits in the cornea of the eye, eye drops containing cysteamine are administered. Correction of electrolyte disturbances also takes place. Hemodialysis is performed to treat renal insufficiency. Sometimes a transplantation of the kidneys may be necessary. This form of treatment has been shown to be very effective.
Outlook and prognosis
The prognosis is unfavorable and depends on the form of cystinosis. This is determined by the age of manifestation of the patient and can be fatal in the worst cases. The hereditary disease is treated symptomatically, since no cure is possible with the available options. Nevertheless, significant medical progress has been made in recent years, resulting in symptom relief as well as prolonging the existing lifespan. The prospects of improved well-being as well as an increase in the quality of life have been achieved to a large extent by the new therapeutic options. The older the patient is at the first signs of the disease, the better his chances are. There are three types of cystinosis, which are essentially linked to the age of the patient. In infantile nephropathic cystinosis, kidney dysfunction occurs after only a few months of birth. This is the most common form of cystinosis and it occurs in infants as young as 6 months of age. Without medical care, the health condition worsens and kidney failure occurs. The prognosis improves as soon as there is a possibility of kidney transplantation. It can ensure the survival of the affected person, but numerous side effects or sequelae occur. Therefore, even with a donor kidney, a cure is not achieved.
Prevention
Cystinosis is among the congenital diseases that are inherited. For this reason, no preventive measures are possible.
Follow-up
Whether special measures of an aftercare are available to the affected person in case of cystinosis can usually not be predicted in general. These depend thereby strongly on the cause and also on the treatment of the Cystinose, whereby the concerning should already contact a physician with the first symptoms and signs of this illness.The earlier a doctor is consulted and treatment is initiated, the better the further course of the disease usually is. The treatment itself is usually carried out by taking medication and other supplements. The affected person should pay attention to a regular intake and also to a correct dosage. In the case of children, it is above all the parents who must check that the medication is being taken appropriately. Furthermore, a regular diet can also alleviate the symptoms of cystinosis. In this case, the attending physician can also prepare a diet plan for the affected person, which can alleviate the symptoms. Since the disease can lead to damage of the internal organs, regular examinations by an internist are also very useful. In particular, the kidneys should be examined. Possibly, there is a reduced life expectancy of the affected person due to this disease.
This is what you can do yourself
Cystinosis is a hereditary disease and cannot be treated causally. Affected individuals can therefore do nothing to combat the causes of the disease. It is imperative that any symptoms that occur be examined by a physician. The most common form of cystinosis is the infantile nephropathic form, which occurs in infants from about six months of age and is usually associated with kidney dysfunction. To alleviate the symptoms, affected children should receive phosphate and vitamin D. This prevents rickets. This prevents rickets. However, young parents often feel overwhelmed in this situation. They can find support from self-help associations, which are also active online. Cystinosis self-help groups inform affected parents about the current state of research, try to answer questions from everyday life and also establish contact with other families with children suffering from cystinosis. If requested, the staff of these associations will also accompany parents to meetings with doctors, educators or school administrators. Some self-help groups also provide videos and other informational materials that can be used to educate the social environment of affected children about the disease. In addition, many hospitals also offer special cystinosis consultations.
