Abstract: Objective To summarize the clinical characteristics of a case of infantile cystinosis in order to improve clinicians' understanding of the disease. Method The clinical features of one case of infantile cystinosis were retrospectively analyzed. Results A 2 -year-old boy was admitted to hospital due to growth retardation in height for more than 1 year and weakness of lower extremities for 3 months. The boy presented with physical development retardation, lower extremities weakness, rickets, metabolic acidosis, hypophosphatemia, glycosuria, ketonuria, aminoaciduria, low-molecular-weight proteinuria and hypercalciuria. Genetic variation analysis showed complex heterozygous variation of CTNS gene. One was a splicing variation of c.140 +1G>C from the father, and the other was a missense variation of c.969C>G (p.N323K) from the mother, and the child was diagnosed as cystinosis (infantile type). Conclusions Infantile cystinosis is more common in infant, and the first clinical manifestations are mainly physical retardation and abnormal urine examination. Clinically, it was often misdiagnosed as Fanconi syndrome.

Key words: cystinosis; nephropathy; infantile type