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At least 19 recordsLinked to original sources
PubMed1989

Cystinuria in dogs: comparison of the cystinuric component of the Fanconi syndrome in basenji dogs to isolated cystinuria.

Two animal models for cystinuria have been examined: the Basenji dog with Fanconi syndrome and cystine stone-forming dogs of various breeds. Brush-border membranes were isolated from these animals and uptake of D-glucose and L-cystine was characterized. Experiments with isolated brush-border vesicles from Basenji dogs with cystinuria as a component of the Fanconi syndrome showed diminished sodium-dependent D-glucose uptake but no decrease in L-cystine uptake even though the cystine defect in vivo was as high as 94% (ie, 6% reabsorption). In contrast, brush-border vesicles isolated from the kidney of a cystine stone-forming dog (Welsh Corgi) with a cystine defect of only 16% (ie, 84% reabsorption) had decreased uptake of cystine compared to values found for Beagle and Basenji vesicles. Thus, cystinuria found in Basenji dogs with the Fanconi syndrome differs from that in classic stone-forming cystinuric dogs. The alteration responsible for the cystinuria of Basenji dogs with Fanconi syndrome does not appear to have a membrane locus and may reflect altered energetics for transport, which are not detected in isolated vesicles. The cystine defect in cystinuric stone-forming dogs does appear to be reflected in the isolated membrane.

Amino Acids↗
PubMed1985

Ontogeny modifies manifestations of cystinuria genes: implications for counseling.

Among 339,868 newborn infants screened at 3 weeks of age (91% compliance rate), 730 had elevated rates of excretion of cystine and the dibasic amino acids lysine, ornithine, and arginine; 191 infants had persistent "infantile cystinuria" on follow-up screening (100% compliance). Apparent incidence of the phenotype was 562 per million infants; this rate is seven times higher than for classic cystinuria in the adult segment of the Quebec population. We studied longitudinally 26 probands 2 to 4 months of age. Initially, each excreted cystine and dibasic amino acids at much higher levels than did normal infants or either parent. From parental phenotypes (heterozygous or homozygous normal) and urine amino acid excretion values at 6 months of age in probands, the infants were classified as either heterozygous for the various classic cystinuria genotypes--type I ("silent"), eight infants; type II (high excretor), three; type III (moderate excretor), nine--or homozygous (and genetic compound), six. Urine amino acid excretion diminished steadily with age, to reach the variant parental value in heterozygous infants but not in homozygotes. Cystinuria heterozygotes, with the possible exception of some type I individuals, could not be distinguished reliably from homozygotes in early infancy, although homozygotes had significantly higher excretion values as a group. We deduce that renal ontogeny amplifies phenotypic expression of cystinuria alleles, thus influencing correct classification of genotype (heterozygote vs homozygote, and type of allele). These findings have implications for counseling and the need for follow-up of infantile cystinuria.

Aging↗
PubMed1987

Cystine fluxes across the isolated jejunal epithelium in cystinuria: increased efflux permeability at the luminal membrane.

In cystinuria, renal clearance of cystine frequently exceeds creatinine clearance, suggesting net cystine secretion; and absorption of the (di)basic amino acid is impaired at the luminal membrane of the jejunal and probably also renal tubular epithelium. We studied cystine transport in vitro in jejunal biopsy specimens of eight subjects with homozygous cystinuria and in 12 controls. Cellular/medium cystine distribution ratio was reduced in cystinuria (1.36 +/- 0.36 versus 5.36 +/- 0.61, p less than 0.001). Cystine influx across the luminal membrane was normal (221 +/- 48 versus 261 +/- 79 pmol X h-1 cm-2). Measurement of transepithelial cystine fluxes showed net absorption in controls but secretion in cystinuria. Apparent permeability coefficients were close to normal in cystinuria except that the efflux permeability at the luminal membrane was significantly increased (0.839 +/- 0.22 versus 0.186 +/- 0.12 X h-1 cm-2), and, accordingly, at the luminal membrane, the influx over efflux permeability ratio was small (1.01 +/- 0.50 versus 4.95 +/- 0.80, p less than 0.001). The defect in cystine transport in cystinuria is apparently not caused by decreased influx but increased efflux of cystine (or cystine) from the cell to the lumen across the luminal membrane.

Adult↗
PubMed1975

Subacute combined degeneration of the spinal cord with cystinuria.

An 18-year-old man had noticed increasing difficulty in walking for 4 years. Examination disclosed spastic paraparesis and posterior column signs suggestive of subacute combined degeneration of the spinal cord. Urinalysis, urinary thin-layer chromatography, and intestinal biopsy disclosed typical cystinuria. Pernicious anemia and other known enteropathies were excluded. Although this could be a chance association of cystinuria and subacute combined degeneration, one other paper has reported a cystinuria patient with similar neurologic findings. A chance association between cystinuria and nonpernicious anemia subacute combined degeneration of the spinal cord should occur only once in 120 million individuals. Thus, identification of only a few more cases would suggest a pathogenetic link between the two disorders. These observations emphasize the need to search for neurologic signs in patients with cystinuria and to screen the urine of patients with spinal cord signs of obscure origin for cystinuria.

Adolescent↗
PubMed1991

Diagnostic and genetic studies in 43 patients with classic cystinuria.

We present results for laboratory screening and diagnostic tests--cyanide-nitroprusside test, semi-quantitative thin-layer chromatography, and quantitative amino acid column chromatography--of 43 patients with classic cystinuria. We report the efficaciousness of the cyanide-nitroprusside test and of thin-layer chromatography, as compared with quantitative amino acid chromatography, for detecting heterozygotes for type II or III cystinuria. The quantitative results for aminoaciduria in 57 blood relatives in 23 families were used to categorize the index patients with classic cystinuria. By column chromatography the ranges of excretion rates (mumol/24 h per 1.73 m2 body surface area) of diagnostic amino acids in the index patients were as follows: cystine 556-54044 (normal 20-128), arginine 131-11543 (10-80), lysine 768-21848 (51-514), ornithine 185-5685 (0-80). Also by column chromatography the median values for arginine and ornithine excretion in cystine-lysinuric heterozygotes (among the 57 blood relatives) were significantly higher (P less than 0.01) than in controls but never approached the values for homozygotes. The cyanide-nitroprusside test results were positive in urine samples of 41 of 43 index patients and in 16 (51.6%) of the urine samples of 31 obligate heterozygotes with column chromatographically proven cystine-lysinuria. Thin-layer chromatography detected all of the homozygotes, all the compound heterozygotes, and 54.8% of the carriers. According to the type of aminoaciduria in their relatives, 11 patients with classic cystinuria could be classified as having classic cystinuria type I, 11 as having type II or III, and three as being compound heterozygotes. We discuss the implications of these results for correct diagnoses and for genetic studies in classic cystinuria.

Amino Acids↗
PubMed1989

Cystinuria and its treatment: 25 years experience at St. Bartholomew's Hospital.

Cystinuria is an inherited condition affecting the active transport of the diamino acids cystine, ornithine, lysine and arginine across the renal tubule and the small intestine. The only clinical effect is the production of urinary tract stones and if these can be prevented the affected individuals can lead a normal life. In many people cystine stones can be dissolved and new stone formation prevented by a high fluid intake, but if this does not succeed regular treatment with penicillamine will do so. Although many side-effects have been described with penicillamine treatment it is rare for them to be severe enough to prevent its use in patients with cystinuria. Since the clinical effects of cystinuria can be prevented by either a high fluid intake or by penicillamine it is important to make the diagnosis in affected individuals as soon as possible and cystinuria should therefore be considered in all people (regardless of age) who form urinary stones.

Cystinuria↗
PubMed2026

Generation of a novel Slc7a9G105R mutant mouse identifies new biomarkers for cystinuria.

INTRODUCTION: Cystinuria is a rare inherited disease characterized by increased urinary cystine levels resulting in the formation of cystine stones in the urinary tract. Mutations in the genes encoding the cystine transporter complex, SLC3A1 and SLC7A9, are the primary drivers of the disease. Current mouse models used to study cystinuria rely on gene deficiency or spontaneous mutations in mice that do not accurately reflect the pathogenic mutations found in humans. METHODS: We generated a novel Slc7a9G105R knock-in mouse model in which glycine at position 105 is replaced by arginine, recapitulating the most common pathogenic mutation in human SLC7A9. Disease onset and progression were assessed using micro-CT imaging, fecal metagenomics, and urine and serum metabolomics and proteomics. RESULTS: Both male and female Slc7a9G105R mice developed a cystinuria phenotype by nine weeks of age, characterized by substantial cystine stone formation and increased urinary cystine, lysine, arginine, and ornithine. Slc7a9G105R mice displayed distinct serum and urinary metabolite profiles, mapped to dibasic amino acid pathways, and serum protein profiles, mapped to disease progression. Fecal metagenomics revealed that Slc7a9G105R mice had a heterogeneous microbiota with altered functional pathways, including increased L-cysteine biosynthesis. Antibiotic-induced depletion of the microbiota did not affect cystine stone burden but reduced urinary tract inflammation. Prophylactic or therapeutic dietary supplementation with alpha-lipoic acid reduced stone burden and inflammation, but it also caused urothelial damage. Untargeted metabolomics analysis following alpha-lipoic acid supplementation identified metabolites that can increase cystine solubility, reduce inflammation, and damage epithelial cells. Correlation analysis revealed novel serum metabolite biomarkers of stone burden, including 2-hydroxybutyric acid and 2-amino-2-thiazoline-4-carboxylic acid, which were also detected in human serum. CONCLUSIONS: Collectively, the Slc7a9G105R mutant mouse model offers a precise, rapid-onset, and translational platform for investigating cystinuria pathogenesis and evaluating potential therapeutic strategies.

SLC7A9↗
PubMed1979

Childhood cystinuria in New South Wales. Results in children who were followed up after being detected by urinary screening in infancy.

Homozygous cystinuria was diagnosed in 45 children and 19 of their siblings in the course of routine urine screening of 6-week-old infants in New South Wales. These children were followed for up to 14 years. During this time there were 5 clinical episodes of renal disease which could be ascribed to cystinuria. There was normal mental development in all the children except one. Of 49 children over 3 years, 4 had height centiles less than the midparent height centile, while 45 had height centiles equal to or above the midparent centiles. Family testing in these 45 cases showed that 60% were type I cystinurics, and 35% were of the mixed or compound type (5% were not classified). Data from the parents and grandparents showed that renal tract calculi had occurred in 14 of them. This study shows that children with homozygous cystinuria, detected by urinary screening in infancy, rarely have renal symptoms. Mental development was normal as was growth in height. There was an increased incidence of noncystine stone formation among the relatives of these children. The incidence of homozygous cystinuria in New South Wales in one in 17 286.

Adolescent↗
PubMed1971

Biochemical and genetic studies in cystinuria: observations on double heterozygotes of genotype I-II.

10 families with cystinuria were investigated by measuring: (a) quantitative 24 hr urinary excretion of amino acids by column chromatography; (b) endogenous renal clearances of amino acids and creatinine; (c) intestinal uptake of (34)C-labeled L-cystine, L-lysine, and L-arginine using jejunal mucosal biopsies; (d) oral cystine loading tests. All four of these were studied in the probands and the first two in a large number of the family members.49 members of 8 families were found to have a regular genetic pattern as described previously by Harris, Rosenberg, and their coworkers. Clinical or biochemical differences between the homozygotes type I (recessive cystinuria) and homozygotes type II (incompletely recessive cystinuria) have not been found. Both types excreted similarly excessive amounts of cystine, lysine, arginine, and ornithine, and had high endogenous renal clearances for these four amino acids. Some homozygotes of both types had a cystine clearance higher than the glomerular filtration rate. Jejunal mucosa from both types of homozygotes exhibited near complete inability to concentrate cystine and lysine in vitro. This was also documented in vivo with oral cystine loads. The heterozygotes type I were phenotypically normal with respect to the above four measurements. The heterozygotes type II showed moderate but definite abnormalities in their urinary excretion and their renal clearances of dibasic amino acids. Of the four amino acids concerned, cystine was the most reliable marker to differentiate between the heterozygotes type II and the homozygous normals. In this study, type III cystinuria, as described by Rosenberg, was not encountered. In two additional families, double heterozygotes of genotype I/II were found. The disease affecting these is clinically and biochemically less severe than that affecting homozygotes of either type I or type II. With respect to the four parameters used in this study, the double heterozygotes type I/II have results which are intermediate between those of the homozygotes type I and II and those of the heterozygotes type II.

Adolescent↗
PubMed1992

Bardet-Biedl syndrome and cystinuria.

An unusual association of Bardet-Biedl syndrome with cystinuria was described in one patient. A 21-year-old male was admitted to hospital because of renal failure, severe deterioration of visual acuity, polydactyly, brachydactyly, and mental retardation. Laboratory investigations revealed a serum creatinine of 292 mumol/L (3.3 mg/dL) and a GFR of 25 mL/min per 1.73 m2. Quantitative ion exchange chromatography demonstrated an increased urinary excretion rate of cystine, lysine, arginine, and ornithine. The ophthalmologic examination showed a severe atypical retinal dystrophy. Visual acuity was severely deteriorated and the patient could only count the examining physician's fingers. The patient had been previously evaluated at the age of 7 years for polyuria, polydipsia, and growth failure. His workup at that time demonstrated nephrogenic diabetes insipidus, normal GFR, and a urinary amino acid pattern consistent with the cystinuric phenotype. There was mental retardation notwithstanding the normal ophthalmologic examination. Intravenous pyelography showed calyceal clubbing, calyceal cysts, and lobulated renal outlines of the fetal type. The patient was evaluated again at the age of 13 years for deterioration of visual acuity and the ophthalmologic examination showed an atypical retinal dystrophy, with sparse pigmentation, central and peripheral atrophy, attenuated vessels, and marked optic disk pallor. To our knowledge the association of Bardet-Biedl syndrome with cystinuria has never been reported. It is unlikely that cystinuria may have contributed to the kidney damage. The possibility that mental retardation has been induced or aggravated by cystinuria cannot be excluded.

Adult↗
PubMed1990

A case of nephrotic syndrome due to alpha-mercaptopropionyl glycine in a patient with familial cystinuria.

A 26-year-old male with nephrotic syndrome (NS) due to alpha-mercaptopropionyl glycine (MPG) is described. In March, 1988, he was diagnosed as having familial cystinuria after receiving urolithiasis treatment since December, 1985. Massive proteinuria and slight pedal edema were noted. Nephrotic syndrome was suggested and renal biopsy was performed. The renal pathological finding demonstrated membranous glomerulonephritis (MN) at stage I. This case was defined as NS clinically associated with MPG, and glucocorticoid intake was initiated. The response to the glucocorticoids was fairly good with no clinical problems after discontinuation of MPG, and the cystinuria was maintained with alkaline medication. The patient's parents and younger brother were suggested and confirmed to have cystinuria based on urinary aminogram analysis, but displayed no symptoms. We present a rare case of NS due to MPG therapy in a patient with familial cystinuria. However, the mechanism of onset remains unclear.

Adult↗
PubMed1988

[Distribution of cystinuria subtypes in the Democratic Republic of Germany].

The classic cystinuria is a hereditary disorder characterized by a defective transport of cystine and the dibasic amino acids arginine, lysine and ornithine in the epithelial cells of the renale tubule and the gastrointestinal tract. The excretion patterns of cystine and the dibasic amino acids in 24-hour urine samples from heterozygotes can be used to the differentiation between the genetic subtypes. 120 probands in the age range from 3 to 70 years from 22 families with cystinuria were investigated by thin-layer chromatography and by ion exchange chromatography. In patients with cystinuria the genotype I-I has a frequency of 50%. These results and the distribution of the other subtypes are in accordance with published data. From 98 persons investigated in 22 families with cystinuria 14 run the risk to form cystine stones. Therefore, the knowledge of the subtypes is relevant for practice.

Adolescent↗
PubMed1977

CNS lesions in cystinuria.

A man with cystinuria developed, at the age of 23, a neurological disorder with relapses and remissions similar to multiple sclerosis. This is the third documented case of cystinuria with central neuraxis lesions, and it is suggested that neurological complications may occur in cystinuria more frequently than is generally recognized.

Adult↗
PubMed1985

Heterozygous cystinuria and urinary lithiasis.

Cystinuria is a recessively inherited transport disorder, with at least three mutant alleles (I, II, and III) demonstrable. I/I, II/II, and III/III homozygotes and I/II, I/III, and II/III compound heterozygotes (cystinuric patients) have high urinary concentrations of cystine, lysine, arginine, and ornithine and frequently form cystine stones. +/I heterozygotes (nondetectable) are phenotypically normal, whereas +/II and +/III heterozygotes (detectable) show variable increases in urinary cystine and lysine concentration and at times increases in urinary arginine levels. The objectives of the present study were to determine the frequency of +/II heterozygotes among stone-forming and nonstone-forming individuals from the same region of Brazil and to evaluate the possible relationship between heterozygous cystinuria and urinary lithiasis. When urine samples from 5,150 individuals (5,000 nonstone-forming individuals and 150 stone-forming individuals) were screened by the qualitative cyanide-nitroprusside cystine test, by thin-layer amino acid chromatography, and by quantitative amino acid determination by ion-exchange chromatography, 32 +/II or +/III heterozygotes (26 nonstone-forming and six stone-forming individuals) were detected. The frequency of detectable heterozygotes among the stone-forming individuals (1:25) was significantly higher than that among nonstone-forming individuals (1:104), which provides additional evidence that heterozygosity for +/II and +/III cystinuria is a risk factor in the formation of urinary stones. No significant difference was detected in urinary cystine concentration or in terms of the various characteristics of urolithiasis when stone-forming heterozygotes were compared to nonstone-forming heterozygotes. These data suggest that the tendency towards stone-forming among heterozygotes is probably owing to a complex and multifactorial mechanism.

Arginine↗
PubMed1975

Phenylketonuria in a patient with cystinuria.

During routine screening procedures for amino-acid disorders by thin-layer chromatography, a 16-year-old boy was found to have phenylketonuria and cystinuria. A phenylalanine and a cystine loading were carried out. The patient was found to be homozygous for phenylketonuria and heterozygous for cystinuria type II. His father was heterozygous for phenylketonuria and cystinuria, while his mother proved to be heterozygous only for phenylketonuria.

Adolescent↗
PubMed1986

Frequency of cystinuria among stone-forming patients in region of Brazil.

Occasional urine samples from 200 stone-forming individuals were screened by the successive application of the cyanide-nitroprusside test, qualitative-semiquantitative thin-layer amino acid chromatography, and quantitative ion-exchange amino acid analysis to determine the frequency of cystinuria in this region of Brazil. Only 1 homozygous cystinuria patient was detected, a lower frequency than 1 to 6 per cent reported in other countries. The patient's family showed a I/I genotype. Since 6 heterozygotes for cystinuria +/II or +/III were also detected, the relative rarity of homozygotes in this sample supports the view of the relatively greater contribution of etiologic factors other than gene frequency to stone formation. The importance of diagnosis based on quantitative amino acid analysis is emphasized because of the different therapeutic and prognostic implications of the homozygote and heterozygote forms of the disease.

Amino Acids↗
PubMed1979

Heterozygous cystinuria and calcium oxalate urolithiasis.

Many variables are known to be associated with the formation of calcium oxalate urolithiasis but none is essential for the initiation or growth of stones. It is likely that the predisposition to stone formation is related to multiple factors. We herein describe still another metabolic state that seems to predispose to calcium oxalate stone disease, namely heterozygosity for cystinuria. Cystine screening tests were done on 24-hour urine specimens obtained from 126 patients in whom recurrent calcium oxalate stones form and 84 controls and quantitative amino acid determinations were done on all positive specimens. Of those studied 17 of 126 stone patients and 1 of 84 controls were heterozygous cystinurics. A test of the differences between the relative frequencies of cystinuria heterozygotes in the 2 groups with Fisher's exact test revealed them to be highly significant (p less than 0.001). Our study indicates that carrier status for 1 of the cystinuria genes predisposes to calcium oxalate stone formation but, like other factors related to urolithiasis, it is not a necessary cause of stone disease.

Adolescent↗
PubMed1976

Cystinuria: a new genetic variant.

1. A family is reported with an unusual type of cystinuria. 2. The propositus presented with a cystine renal stone; the renal tubular reabsorption of cystine was grossly abnormal but the tubular reabsorption of ornithine, lysine and arginine was only slightly less than normal. 3. One of the children of the propositus escreted cystine and lysine in increased amounts typical of type II heterozygotes for cystinuria. 4. The renal transport defect in this family may represent one end of the spectrum of cystinuria or it may be a form akin to isolated hypercystinuria.

Amino Acids↗