Cystinosis

Nephropathic cystinosis is an autosomal recessive inborn error of metabolism characterized by the lysosomal storage of the disulphide amino acid cystine. It produces a variety of clinical manifestations including failure to thrive, the renal Fanconi syndrome, eye findings, and end-stage renal disease. A variety of phenotypes are known; however, the molecular defect underlying any of the forms has not yet been identified. Therapy of cystinosis with cysteamine averts the otherwise inevitable renal failure, but systemic therapy does not improve the corneal keratopathy. A number of presentations in this review detail approaches to gene identification, systemic therapy with cysteamine, measurement of cystine, and pathophysiological effects at the cellular and clinical level.