A European Multicenter Study to Evaluate Cysteamine Toxicity on Human Osteoclasts in Nephropathic Cystinosis Patients

What this Trial Is About

Nephropathic Cystinosis (NC) is a rare inherited disease caused by a deficiency in the cystine lysosomal transport protein, cystinosin. This condition leads to a generalized lysosomal storage disorder and is usually treated with cysteamine. Bone problems have been identified as a late complication in NC patients, especially during adolescence or early adulthood, possibly due to cysteamine toxicity or effects from the CTNS mutation. The study aims to better understand how cysteamine affects bone cells and to describe the bone health of NC patients according to their genetic background. This observational study involves NC patients who are currently receiving cysteamine treatment. Researchers will collect blood samples to evaluate the effect of cysteamine on the formation and activity of bone-resorbing cells called osteoclasts. The study will assess this relationship based on patients' genotypes to understand differences in bone disease progression. Participants will provide a 25 mL blood sample for analysis of osteoclastic cells. Researchers will measure the number of specific cells called Tartrate-resistant acid phosphatase (TRAP) positive cells one day after sample collection. The study also includes clinical assessments of patients' bone status depending on their genotype. Participants and/or their guardians must agree to participate, with the study lasting until October 2026.

CYSTEA-BONE Clinical Study