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Background: Cystinuria, one of the first diagnosed inborn errors of metabolism, recognized by hyperexcretion of cystine, lysine, ornithine and arginine into the urine. So far, two genes associated with cystinuria have been identified: SLC3A1 (2p16.3) that encodes the heavy subunit rBAT of the renal b0,+ transporter and SLC7A9 (19q13.1), which encodes the light subunit b0,+AT. Patients with type A cystinuria have two SLC3A1 mutations, whereas patients with type B have two SLC7A9 mutations and finally patients with type AB have one mutation in each gene. Considering the population-specific distribution of mutations in disease, limited studies on the genetic bases of the cystinuria have been done in Middle East. This research presents the results of mutation analysis on patients with cystinuria in Iran. Methods: Thirty unrelated patients with cystinuria operated to remove kidney stones were screened by urologist .The patients were analyzed for mutation using amplification refractory mutation system (ARMS) and polymerase chain reaction-Restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) methods. Findings: We found some variations including missense mutations, polymorphism and intron variant, but the most frequent mutations, M467T and also T216M and R333W, were not detected in our patients. Conclusion: Our research may confirm the ethnic distribution of mutations in cystinuria and this study can expand our concept of the genetic basis of cystinuria in Iranian patients.

Telomeres consist of repetitive DNA sequences and a variety of non-nucleosomal proteins which are essential to survive chromosome. Telomeres protect the ends of chromosomes, but can also inhibit the expression of nearby genes, called telomere position effect. The telomeric cap is a dynamic structure between a fully capped closed and a partially uncapped or open conformation. The protection of chromosome termini from being sensed by the cell as broken DNA is an important function of the telomeres as the capping function. Functional telomeres have a special role in response to DNA damage. The presence of telomere and the length of telomere are two important determinants for binding of chromosomes to the nuclear envelope in meiosis. Future studies about the characteristics of epigenetic factors in telomere length will lead to a better understanding of telomere regulation and its role in human cancers. It seems that telomere dysfunction, rather than telomere length alone, may create insights not only into the pathogenesis, but could also have significant impact on the diagnosis of cancer. Keywords: Role, Telomere, Tumorigenesis, Telomere dysfunction

Telomeres are special structures at the ends of chromosomes, especially in eukaryotes, that include repetitive sequences of deoxyribonucleic acid (DNA) and non-nucleosomal proteins. These structures are essential to protect chromosomes from recombination and degradation. Telomeres are gene-poor repetitive sequences, but they are close to the more gene-rich subtelomeric regions. Proteins associated with telomeres are able to interact directly with the TTAGGG repeats and also can bind to other factors to form large protein complexes. These proteins are involved in DNA repair and telomere stability. Therefore, defects in the synthesis of these proteins could induce imperfections in telomere maintenance and DNA repair; and accordingly, should cause a number of genetic syndromes. Keywords: Telomere, DNA damage, Genetic diseases