A Novel Mutation in A Patient With Cystinosis

Background and aim: cystinosis is an autosomal recessive disorder characterized by an accumulation of the amino acid cystine in lysosomes throughout the body. cystinosis is an inherited disease resulting from failure of lysosomal cystine transport. the responsible gene ctns, encoding the lysosomal cystine carrier cystinosin.methods: in this study, we reviewed genetic basis of cystinosis and introduced a novel mutation in an iranian case. a 9 years old symptomatic female with renal insufficiency was diagnosed as having cystinosis based on her clinical features and laboratory tests. after genetic counseling, blood samples were obtained from the patient and her parents. genomic dna was extracted from whole blood and mutation analysis was performed using pcr and sequencing methods for all exons of ctns gene.at least 148 different pathogenic and deleterious mutations in ctns gene have been reported up to date.results: based on prominent clinical features of cystinosis in our patient, we carried out a targeted search for mutations in ctns gene. this led us to identify a novel homozygous dna variation c.256_257delct in exon 6 of the gene. as expected, the mentioned mutation existed in both her parents in a heterozygous state.conclusion: the variation c.256_257delct in ctns gene is a frame shift and truncating mutation that affects product function and result in relatively mild signs and symptoms of cystinosis. the present finding will be useful for genetic diagnosis and carrier detection in the family and for other patients with similar disease manifestations.