Cystinuria is a frequent inherited metabolic disorder in Czech population (frequency 1/5 600 of live births). It is caused by a defect in the renal transport of cystine and dibasic amino acids (arginine, lysine and ornithine). The disease is characterized by increased urinary excretion of amino acids and often leads to recurrent urolithiasis. For many years cystinuria has been classified into three subtypes based on the urinary excretion of cystine and dibasic amino acids in obligate heterozygotes and intestinal absorption in homozygotes. Cystinuria is currently classified into two subtypes (type I and type non-I) based on urinary excretion of cystine and dibasic amino acids in obligate heterozygotes. Two genes coding for proteins constituting heterodimeric transporter are currently associated with cystinuria. Cystinuria type I is caused predominantly by mutations in the SLC3A1 gene (2p16.3) encoding a heavy subunit (rBAT) of the heterodimeric transporter. Cystinuria non-I type is caused by mutations in the SLC7A9 gene (19q13.1), encoding a light subunit (b0+AT) of this transporter. Despite extensive research in the field, many questions still remain open.

        Key words: cystinuria, SLC3A1, SLC7A9, transport.