Cystinosis is a rare autosomal recessive disorder resulting from defective 
lysosomal transport of cystine due to mutations in the cystinosin lysosomal 
cystine transporter (CTNS) gene. The clinical phenotype of nephropathic 
cystinosis is characterized by renal tubular Fanconi syndrome and development of 
end-stage renal disease during the first decade. Although metabolic acidosis is 
the classically prominent finding of the disease, a few cases may present with 
hypokalemic metabolic alkalosis mimicking Bartter syndrome. Bartter-like 
presentation may lead to delay in diagnosis and initiation of specific treatment 
for cystinosis. We report a case of a 6-year-old girl initially presenting with 
the features of Bartter syndrome that was diagnosed 2 years later with 
nephropathic cystinosis and a novel CTNS mutation.