Cysteamine therapy: a treatment for cystinosis, not a cure

Abstract

Cystinosis as a clinical entity is a progressive dysfunction of multiple organs caused by the accumulation of cystine in the tissues, leading, for example, to end-stage renal failure, diabetes, hypothyroidism, myopathy, and central nervous system deterioration. Brodin-Sartorius and colleagues present a long-term study on the impact of cysteamine therapy on these complications. The data show that cysteamine improves the outcome and complications of cystinosis but does not prevent them.

Figure 1. Physiopathology of cystinosis

Cystinosis is a monogenic hereditary disease caused by mutations or deletions in the ubiquitous gene CTNS. This gene encodes a seven-transmembrane lysosomal protein, which is a proton-driven cystine transporter. However, the physiopathology of cystinosis suggests that cystinosin has other functions and/or other genes influence the pace and extent of the disease. This could explain the high variability in age of the appearance and severity of the complications observed in patients taking cysteamine, which allows cystine to exit the lysosomes. ADP, adenosine diphosphate; ATP, adenosine triphosphate; P_i, inorganic phosphate.