Etude d’une maladie héréditaire monogénique: La cystinurie

Abstract

Cystinuria is an inherited, autosomal recessive metabolic disease that is caused by a problem responsible for the renal and intestinal transport of cystine, leading to urinary stones and kidney failure. The objective of this work was to determine the prevalence of cystinuria and to study some epidemiological parameters of this disease, and to analyze urinary stones and crystalluria; in patients referred to the laboratory (STEVA) "urinary lithiasis" at the University of Mostaganem. We consulted all the files of lithiasis patients recruited between 2000 and 2020; there were 16 cases with cystinuria out of a total of 2112 lithiasis patients, giving a prevalence of 0.76%. We noted: sex, age, existence of family history of urolithiasis, consanguinity and possible recurrence, as well as the composition of urinary stones (pure or mixed). The diagnosis was made by morphological analysis of the stones by a stereo microscope and confirmed by an infrared spectrophotometer. A study of crystalluria was performed on fresh urine in the morning. The average age of the patients is 24.9 years. The most affected age group is 30 to 40 years old. There is a male predominance, with an sex ratio of 1.7. The family history was 61.5% and consanguinity 36.4%. The morphological analysis of the stones showed that the stone which characterizes cystinuria is of type Va, it is yellowish in color with a rough surface or made of small stacked crystals of waxy appearance or honey candy the section is poorly organized, sometimes diffuse radial crystalline. Infrared analysis of urinary stones revealed characteristic spectra of cystine (peaks of 845 and 540 cm-1). These calculations were in 87% of cases pure and in 13% mixed. Recurrence was 60%. The study of crystalluria allowed the observation of cystine crystals they are flat and have an irregular hexagonal morphology of 30 to 70μm. In the absence of other diagnostic techniques for cystinuria, morphological and infrared analysis of the stone and the study of crystalluria remain simple and effective means for the diagnosis of this serious disease. This study allowed us to have some epidemiological data on this genetic disease.