This study is designed to describe the relationship between compliance of patients with cystinosis treated with cysteamine and treatment efficacy and to understand the pathophysiologic mechanism of neurological disorders. Is cysteamine crossing the blood brain barrier? What is the impact of cystine accumulation in Cerebro Spinal Fluid and Central Nervous System? Our Primary objective is to study the relationship between compliance of patients treated with cysteamine and the WBC cystine level.