The disease is noticed at about 6 months of age with symptoms of renal tubular dysfunction presenting as the Fanconi syndrome. Renal loss of phosphate leads to hypophosphataemia and rickets. Later there is glomerular damage. In the eye corneal deposits are seen due to the presence of crystalline cystine, and photophobia occurs in most patients. A later onset form with milder renal disease also occurs, referred to as “intermediate” or “adolescent” cystinosis.
Enzyme Tests: The disease may be diagnosed by measurement of [35S]-cystine incorporation.