Abstract

LOPES, Altina et al. Cystinuria: a review and study of molecular bases of 4 patients. Nascer e Crescer [online]. 2010, vol.19, n.4, pp.244-250. ISSN 0872-0754.

Introduction: Classically, based on the phenotype, two types of cystinuria were identified and classified as type I and non‑type I.  More recently a new classification was proposed based on molecular genetics: cystinuria type A (caused by mutations on SLC3A1 gene), type B (involving mutations on SLC7A9 gene) and type AB if there is a digenic inheritance (SLC3A1 and SLC7A9). Objective and methodology: We reviewed the state of the art on the diagnosis, incidence/prevalence, biochemical classification, genetic data and treatment of cystinuria. Furthermore we characterized four patients with cystinuria at molecular level by sequencing SLC3A1 and SLC7A9 genes. Results: On SLC3A1 we detect five mutations, two of them (c.1597T>A and c.611­‑2A>C) are novel and three (c.647C>T; c.1190A>G and c.2019C>G) were been previously reported in literature. Sequencing of SLC7A9 gene showed one (c.614_615insA) previously published mutation. It was possible to classify three type A patients (one homozygote and two compound heterozygotes) and one patient as heterozygous type B, which is consistent with the observed urinary excretion of cystine. Conclusions: Genotypic characterization of patients with cystinuria contributes to the understanding of the pathophysiology, confirms the clinical and biochemical diagnosis and provides genetic counseling to relatives at risk. The authors underline the need of a multidisciplinary team approach in the follow‑up of these patients.

Keywords : cystinuria; nephrolithiasis; amino acids; cystine; SLC3A1; SLC7A9.

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