Actualización de la cistinuria: aspectos clínicos, bioquímicos y genéticos

Abstract

Cystinuria is an autosomal recessive disorder with an estimated incidence of 1 case in 7000 live births, that results in elevated urinary excretion of cystine and dibasic aminoacids: ornithine, lysine and arginine. Discussed by Sir Archibald Edward Garrod, in 1908, as one of the four first known inborn errors of metabolism, it is characterized by a defect in transport of cystine and dibasic aminoacids, that affects their reabsortion in both renal tubule and gastrointestinal tract. To date, according to the recent molecular findings, two genes have been identified as responsible for this disease: SLC3A1 and SLC7A9. A more accurate pheno/genotyping identification of cystinuric patients will allow to improve prophilaxis and therapy for this illness. Cystinuria only causes recurrent urolithiasis (about 1-2 / of renal calculi in adults) and its associated complications as clinical feature because of poor cystine solubility at low pH. An accurate control over prohylaxis (based on high water intake and potassium citrate treatment, on first line, and tiol-derivatives treatment, on second line) must be taken in patients -like homozygous type I- with high lithiasis risk. However, approximately one half of patients under prophylaxis control will develop recurrent lithiasis; in this case, only urology or surgical approaches would be possible. 474 Updated knowledge about biochemical, genetic, clinical, diagnosis, prevention, treatment and prognosis aspects of this, relatively unusual, disease has been reviewed in this article.