Hereditary and genetic, cystinosis results from a mutation in the cystinosin gene. Transmitted in an autosomal recessive manner, this disease requires that both parents carry the mutated gene. Treatments are being considered to mitigate its effects.
1. Definition of cystinosis
Cystinosis, a rare genetic disease, causes an accumulation of cystine in cells due to a problem with lysosomes. There are three forms of cystinosis. The first, classic or nephropathic infantile cystinosis, is the most severe and can lead to serious kidney problems from childhood. Then there is the intermediate form, which presents similar symptoms but later in life, often during adolescence. Finally, there is ocular cystinosis, where only the eyes are affected, leaving the kidneys unharmed. Although cystinosis is rare, it can affect anyone, regardless of their origin. In France, around five new people are affected each year. According to the association Overcoming Lysosomal Diseases, the nephropathic form of cystinosis is present in 95% of affected individuals.
2. Symptoms of cystinosis
The symptoms of cystinosis vary depending on the form of the disease, but they share a number of manifestations that can have a significant impact on the daily life of those affected. Eye problems, such as photophobia (sensitivity to light) and progressive worsening of vision, are common signs of cystinosis, especially in the ocular form. The nephropathic form, the most severe, is characterized by serious kidney problems, often leading to early kidney failure. In all cases, growth retardation is a common symptom, affecting the physical development of affected individuals. These physical symptoms are often accompanied by emotional and social challenges, making management of cystinosis a complex undertaking that may require a holistic approach to improve the quality of life of people living with this rare disease.
3. Diagnosis of cystinosis
The biochemical diagnosis of cystinosis is based on the measurement of cystine inside leukocytes. To determine the presence or absence of associated genetic mutations, molecular diagnosis based on mutation testing can also be performed. Families with a history of cystinosis can opt for prenatal diagnosis, which consists of measuring the level of cystine in cells taken from the amniotic fluid and placed in culture, or in the cells of the chorionic villi, which are the future placenta. It is recommended that all people with cystinosis undergo appropriate examinations, such as kidney function tests, evaluation of thyroid functions, and regular eye examinations to effectively monitor and manage complications related to this disease.
4. Treatment of cystinosis
As stated in the Medical Biological Review, the goal of cysteamine treatment is to reduce the presence of cystine in lysosomes. Children may be prescribed growth hormone to promote growth and increase phosphate reabsorption. Angiotensin-converting enzyme inhibitors may be used to relieve severe glomerular proteinuria. Kidney transplantation is considered when creatinine clearance is very low and azotemia and hypertension are rapidly progressing, although this treats Fanconi syndrome without resolving other multisystem complications.
Currently, oral cysteamine treatment, administered in the form of cysteamine bitartrate, has revolutionized the management of nephropathic cystinosis. However, it must be administered early, regularly and in high doses to slow the progression of the disease. In addition to oral treatment, treatment in the form of eye drops is recommended to prevent and moderate eye damage. Although cysteamine has become a global treatment of choice for cystinosis, patients who do not receive this treatment early and consistently can develop a variety of major complications.
Sources
Read also :
⋙ 5 Misconceptions about genetic diseases
⋙ Kidney pain: when should you consult?
⋙ Low or high leukocytes: how to analyze your results and what rate is worrying?