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[Cystinosis from childhood to adulthood]
1Service de néphrologie pédiatrique AP HP, Hôpital Necker Enfants Malades, Université René Descartes, Paris.
Insights
Nephropathic cystinosis, a metabolic disorder causing cystine buildup, can be managed with early cysteamine treatment. This intervention delays kidney failure and growth issues, improving outcomes for affected children.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Context:
- Nephropathic cystinosis is a rare inherited metabolic disorder.
- Characterized by lysosomal cystine accumulation in multiple organs.
- Leads to progressive kidney damage and failure in childhood.
Purpose:
- To summarize the clinical presentation, diagnosis, and management of nephropathic cystinosis.
- To highlight the impact of early cysteamine treatment on disease progression.
- To discuss the genetic basis and diagnostic tools for cystinosis.
Summary:
- Nephropathic cystinosis presents in infancy with failure to thrive and proximal tubulopathy.
- Early cysteamine therapy significantly alters the disease course, preventing end-stage renal disease and growth failure.
- Diagnosis relies on leukocyte cystine assay; prenatal diagnosis and genetic identification offer further insights.
Impact:
- Early diagnosis and treatment are crucial for improving long-term outcomes in cystinosis.
- Cysteamine therapy transforms the prognosis, mitigating severe complications.
- Understanding the genetic defect provides a basis for improved diagnostics and potential future therapies.
Abstract:
Nephropathic cystinosis is a metabolic disease related to lysosomal cystine accumulation in almost all tissues of the body. The first symptoms set up from 5 or 6 months of age including anorexia vomiting polyurodipsia and failure to thrive associated with a proximal tubulopathy (glycosuria, tubular proteinuria, loss of bicarbonate, potassium, phosphorus, etc.) Treatment by cysteamine dramatically changed the prognostic. If started early this treatment allows to delay and possibly to prevent the spontaneous evolution towards end stage renal disease between 6 and 12 years of age and to avoid the growth failure. On the long term the disease involves other organs: eyes, thyroid endocrine pancreas, muscle and central nervous system. The diagnosis of cystinosis is based on the cystine leukocyte assay allowing also the follow up and the adjustment of the treatment. Prenatal diagnosis is possible on chorionic sample. The gene of this recessive disease, mapping on chromosome 17 was recently identified. This gene encodes a protein of the lysosomal membrane involved in the transport of cystine out of the lysosome. There is a juvenile, late onset, form of cystinosis its main symptom is proteinuria with variable tubular alterations. The so called adult form is asymptomatic its only symptom is corneal deposits most often found by chance examination.