Cystinuria is an autosomal recessive disorder that is characterized by an impaired transport of cystine and dibasic amino acids in the proximal renal tubule and epithelial cells of the gastrointestinal tract. This condition results in an elevated urine concentration of  cystine, lysine, ornithine and arginine. The transport of these amino acids is mediated by the rBAT/b^0,+AT transporter, the subunits of which are encoded by the genes SLC3A1, located on chromosome 2p16.3-21, and SLC7A9, located on chromosome 19q12-13.1. Based on the urinary cystine excretion patterns of obligate heterozygotes, cystinuria is classified into two types: type I and non-type I. Mutations in SLC3A1 gene cause type I cystinuria, while mutations in SLC7A9 gene, are responsible for non-type I cystinuria. Here we present two novel mutations in SLC3A1 gene (C242R and L573X) and three in SLC7A9 gene (G73R V375I, 1233_1236delACTC). The mutations were determined by direct sequencing. C242R and L573X mutations in SLC3A1 gene, and G73R mutation in SLC7A9 gene were found in patients from Serbia, V375I in SLC7A9 gene was found in a patient from Macedonia, while 1233-1236del ACTC mutation in SLC7A9 gene was found in a patient from Turkey.

Key words: Cystinuria, SLC3A1, SLC7A9, mutations, rBAT/b^0,+AT transporter