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Context: Children with nephropathic cystinosis (NC) show persistent hypophosphatemia, due to Fanconi syndrome, as well as mineral and bone disorders related to chronic kidney disease (CKD); however, systematic analyses are lacking., Objective: To compare biochemical parameters of bone and mineral metabolism between children with NC and controls across all stages of CKD., Design: Cross-sectional multicenter study., Setting: Hospital clinics., Patients: Forty-nine children with NC, 80 CKD controls of the same age and CKD stage., Main Outcome Measures: Fibroblast growth factor 23 (FGF23), soluble Klotho, bone alkaline phosphatase (BAP), tartrate-resistant acid phosphatase 5b (TRAP5b), sclerostin, osteoprotegerin (OPG), biochemical parameters related to mineral metabolism, and skeletal comorbidity., Results: Despite Fanconi syndrome medication, NC patients showed an 11-fold increased risk of short stature, bone deformities, and/or requirement for skeletal surgery compared with CKD controls. This was associated with a higher frequency of risk factors such as hypophosphatemia, hypocalcemia, low parathyroid hormone (PTH), metabolic acidosis, and a specific CKD stage-dependent pattern of bone marker alterations. Pretransplant NC patients in mild to moderate CKD showed a delayed increase or lacked an increase in FGF23 and sclerostin, and increased BAP, TRAP5b, and OPG concentrations compared with CKD controls. Post-transplant, BAP and OPG returned to normal, TRAP5b further increased, whereas FGF23 and PTH were less elevated compared with CKD controls and associated with higher serum phosphate., Conclusions: Patients with NC show more severe skeletal comorbidity associated with distinct CKD stage-dependent alterations of bone metabolism than CKD controls, suggesting impaired mineralization and increased bone resorption, which is only partially normalized after renal transplantation., (© Endocrine Society 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Temporal changes in kidney transplant outcomes for cystinosis are unknown. We used the SRTR to identify all kidney transplants performed for cystinosis in patients younger than 31 years between 1987 and 2017. We divided time into three equal eras (1987-1997, 1998-2007, and 2008-2017) to assess changes in outcomes using Cox proportional and linear regression models. We examined 441 transplants in 362 patients. Age at ESRD progressively increased (12.1 vs 13.3 vs 13.4; P = .046). Eras 2 and 3 had lower risk of acute rejection (aHR 2 vs 1:0.45; P < .001) (aHR 3 vs 1:0.26; P < .001) and higher 5-year mean GFR (difference 2 vs 1:9.2 mL/min/1.73 m 2 ; P = .005) (difference 3 vs 1:12.9 mL/min/1.73 m 2 ; P = .002) compared with era 1. Five-year graft survival was similar across eras, but 5-year patient survival was higher for era 2 (aHR: 0.25; P = .01). Seventy-nine patients underwent retransplantation. Five-year patient (94.2% vs 92.5%; P = .57) and graft survival (79.1% vs 74.1%; P = .52) were similar between primary and subsequent transplants. Age at ESRD, acute rejection, GFR at 5 years, and patient survival improved over time. Kidney retransplantation is associated with excellent outcomes in children and young adults with cystinosis., (© 2019 Wiley Periodicals, Inc.)

Nephropathic cystinosis is a rare disorder causing the accumulation of intracellular cystine crystals in tissues. The damage to the proximal tubules of the kidneys results in Fanconi syndrome, and patients with cystinosis experience the progression of chronic kidney disease, resulting in the need for kidney transplantation. Treatment of cystinosis with cysteamine has proven to be effective; however, it has many gastrointestinal side effects that are concerning for transplant specialists during the immediate post-transplant period. Transplant specialists routinely discontinue cysteamine therapy for up to six weeks to ensure proper immunosuppressant absorption. This practice is worrisome because it communicates the acceptability of lapses of cysteamine treatment to patients. It may be better to re-initiate cysteamine therapy shortly after transplantation while the patient is followed more closely by the transplant team. This report presents two pediatric patients with nephropathic cystinosis who successfully restarted cysteamine therapy in the immediate post-transplant period without issue in regard to immunosuppression absorption or gastrointestinal side effects. These cases challenge current practice of discontinuing cysteamine therapy during kidney transplantation, and immediate re-initiation of cysteamine therapy in cystinosis patients post-transplant should be considered., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Introduction: infantile nephropathic cystinosis (INC) is an autosomal recessive disorder that causes defects in cystine transport with subsequent accumulation in almost all body tissues, especially kidneys. There are few studies regarding the nutritional status assessment of patients with INC. It has been reported that patients with INC showed increased urinary losses of carnitine, resulting in plasma and muscle carnitine deficiency also increased metabolic requirements of carnitine in this patients have also been proposed, but to date carnitine supplementation is controversial., Objective: the aim of this study was to compare carnitine blood concentrations with nutritional status assessed by three anthropometric parameters: body mass index, mid-upper arm circumference and tricipital skin fold in patients with INC., Material and Methods: anthropometric assessment of 10 patients with INC which included measurement of weight, height, mid-upper arm circumference and tricipital skin fold thickness. Free carnitine (C0) was measured by tandem mass spectrometry in fasting blood samples., Results: a total of 10 patients with INC were analyzed, 5 with and 5 without renal graft. According to the body mass index, 3/10 presented malnutrition. Muscular mass was found low in 8/10 patients (3 without renal graft and all the transplanted) the mid-upper arm circumference showed correlation with C0 blood concentrations (r2 = 0.353); non transplanted patients had C0 levels significantly lower than the transplanted ones (Chi2 = 0.0027)., Conclusion: in this study we found that 70% of patients had low C0 blood levels that had a correlation with depleted lean body mass. It is recommendable to evaluate the nutritional status of these patients as part of their routine medical evaluation., (Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.)

Cystinosis is a rare disease caused by homozygous mutations of the CTNS gene, encoding a cystine efflux channel in the lysosomal membrane. In Ctns knockout mice, the pathologic intralysosomal accumulation of cystine that drives progressive organ damage can be reversed by infusion of wildtype bone marrow-derived stem cells, but the mechanism involved is unclear since the exogeneous stem cells are rarely integrated into renal tubules. Here we show that human mesenchymal stem cells, from amniotic fluid or bone marrow, reduce pathologic cystine accumulation in co-cultured CTNS mutant fibroblasts or proximal tubular cells from cystinosis patients. This paracrine effect is associated with release into the culture medium of stem cell microvesicles (100-400 nm diameter) containing wildtype cystinosin protein and CTNS mRNA. Isolated stem cell microvesicles reduce target cell cystine accumulation in a dose-dependent, Annexin V-sensitive manner. Microvesicles from stem cells expressing CTNS(Red) transfer tagged CTNS protein to the lysosome/endosome compartment of cystinotic fibroblasts. Our observations suggest that exogenous stem cells may reprogram the biology of mutant tissues by direct microvesicle transfer of membrane-associated wildtype molecules.

Cystinosis as a clinical entity is a progressive dysfunction of multiple organs caused by the accumulation of cystine in the tissues, leading, for example, to end-stage renal failure, diabetes, hypothyroidism, myopathy, and central nervous system deterioration. Brodin-Sartorius and colleagues present a long-term study on the impact of cysteamine therapy on these complications. The data show that cysteamine improves the outcome and complications of cystinosis but does not prevent them.

Cystinosis is a rare, autosomal recessive disease with cystine deposits in different tissues. First signs come from kidneys and eyes, but during progression of the disease other organs can also be affected. Previously, patients with cystinosis had a very poor prognosis, but it is now considerably improved due to new methods of treatment. The purpose of this paper is to give a brief review of the disease and discuss the significant improvement of the prognosis, which has been achieved by specific medical treatment with cystine-depleting agents, and, if needed, by kidney transplantation.

Yeagy and colleagues present long-term data from a preclinical model of cystinosis after hematopoietic stem cell transplantation. The results suggest a therapeutic benefit independent of target tissue differentiation but dependent on the level of bone marrow chimerism. The mode of action remains mysterious, but positive effects are seen. Although the work presents a potential therapeutic option for an otherwise dismal disease, the search for the mechanism of action in cellular therapies continues.

The prospect of cell-based therapy for kidney disease remains controversial despite its immense promise. We had previously shown that transplanting bone marrow and hematopoietic stem cells could generate renal cells and lead to the preservation of kidney function in a mouse model for cystinosis (Ctns(-/-)) that develops chronic kidney injury, 4 months post transplantation. Here, we determined the long-term effects of bone marrow stem cell transplantation on the kidney disease of Ctns(-/-) mice 7 to 15 months post transplantation. Transfer of bone marrow stem cells expressing a functional Ctns gene provided long-term protection to the kidney. Effective therapy, however, depended on achieving a relatively high level of donor-derived blood cell engraftment of Ctns-expressing cells, which was directly linked to the quantity of these cells within the kidney. In contrast, kidney preservation was dependent neither on renal cystine content nor on the age of the mice at the time of transplant. Most of the bone marrow-derived cells within the kidney were interstitial and not epithelial, suggesting that the mechanism involved an indirect protection of the tubules. Thus, our model may help in developing strategies to enhance the potential success of cell-based therapy for kidney injury and in understanding some of the discrepancies currently existing in the field.

In the September 2009 issue of Blood, Syres et al. [1] report on syngeneic bone marrow cell (BMC) and haematopoietic stem cell (HSC) therapy as a successful treatment in a mouse model of cystinosis, an autosomal recessive metabolic disease caused by a defect in the transport of cystine across the lysosomal membrane. The accumulation of cystine crystals in lysosomes leads to a multi-organ dysfunction including proximal tubulopathy and renal failure, corneal deposits, myopathy and central nervous system defects. By using Ctns knock-out (Ctns(-/-)) mice as a model for cystinosis, Syres et al. show that BMC transplantation leads to a major reduction of cystine content in all tissues tested, reflected by a significant attenuation of the development and progression of kidney injury and reduction in the number of mice with corneal cystine crystals. These changes were correlated with the engraftment of donor BMC producing a functional cystine transporter in the tissues tested. The transplantation of mouse HSC had the same therapeutic effect than whole BMC in this model, which is important as such HSC can readily be isolated from peripheral blood in humans. This work suggests that BMC or HSC transplantation is a potential treatment for cystinosis and other renal tubular disorders.

Cystinosis is an autosomal recessive metabolic disease that belongs to the family of lysosomal storage disorders. The defective gene is CTNS encoding the lysosomal cystine transporter, cystinosin. Cystine accumulates in every organ in the body and leads to organ damage and dysfunction, including renal defects. Using the murine model for cystinosis, Ctns(-/-) mice, we performed syngeneic bone marrow cell (BMC), hematopoietic stem cell (HSC), and mesenchymal stem cell transplantation. Organ-specific cystine content was reduced by 57% to 94% in all organs tested in the BMC-treated mice. Confocal microscopy and quantitative polymerase chain reaction revealed a large quantity of transplanted BMC in all organs tested, from 5% to 19% of the total cells. Most of these cells were not from the lymphoid lineage but part of the intrinsic structure of the organ. The natural progression of renal dysfunction was prevented, and deposition of corneal cystine crystals was significantly improved in the BMC-treated mice. HSC had the same therapeutic effect as whole BMC. In contrast, mesenchymal stem cell did not integrate efficiently in any organ. This work is a proof of concept for using HSC transplantation as a therapy for cystinosis and highlights the efficiency of this strategy for a chronic, progressive degenerative disease.

Cystinosis is an autosomal recessive lysosomal storage disease that results in renal failure. CNS manifestations are rare. We report a 29-year man who presented with a cervical myelopathy due to cystinosis. Biopsy of the brain lesions demonstrated cystine crystal deposition and an intense perivascular with inflammatory vasculopathic changes. Symptomatic improvement attended the use of higher doses of cysteamine and corticosteroid therapy. Cystinosis of the nervous system may present as spinal cord disease and be associated with a CNS vasculopathy/vasculitis. As more patients with cystinosis experience long term survival, there will likely be an increased frequency of CNS disease.

An 11 year old boy with nephropathic cystinosis developed moderate to severe bilateral optic disc edema two months after he received a deceased donor renal allograft. The bilateral optic disc edema was found to be a result of intracranial hypertension diagnosed by lumbar puncture. No etiology was found. He was treated with acetazolamide and his optic dis edema resolved over a period of eight months and did not recur after acetazolamide was discontinued. The mechanism of intracranial hypertension in patients with nephropathic cystinosis is not well understood, but may involve obstruction of cerebrospinal fluid outflow due to deposition of cystine crystals in arachnoid villi.

Purpose: As a result of successful renal transplantation, patients with nephropathic cystinosis are now living into adulthood. As these patients age, anterior segment ocular complications, other than deposition of corneal crystals, become more evident. With our experience with 172 patients followed up at the National Institutes of Health between 1976 and 2000, the prevalence of anterior segment complications in nephropathic cystinosis was determined., Methods: A cross-sectional examination of age-specific prevalence was performed with logistic regression analysis of prevalence change with age., Results: Besides the corneal crystals apparent in all age groups, superficial punctate keratopathy, filamentary keratopathy, severe peripheral corneal neovascularization, band keratopathy, and posterior synechiae with iris thickening and transillumination were noted in the older age groups. The prevalence increased with age for each complication., Conclusions: As patients with cystinosis grow older, more severe ophthalmic manifestations become evident. It remains to be seen how the prevalence of these complications will be altered by early initiation of oral and topical cysteamine therapy.

Objective: To characterize the pulmonary dysfunction in patients with nephropathic cystinosis after renal transplantation., Design: Cross-sectional analysis of consecutive adult patients., Patients: Twelve adult, nephropathic cystinosis patients and 3 adult, ocular, nonnephropathic cystinosis patients admitted to the National Institutes of Health Clinical Center., Results: The 12 nephropathic cystinosis patients (age range, 21 to 40 years) showed an extraparenchymal pattern of restrictive lung disease, with inspiratory and expiratory dysfunction. Specifically, the mean FVC was 58% of predicted, the mean FEV(1) was 57% of predicted, and the mean total lung capacity was 66% of predicted, while the mean residual volume was normal. Furthermore, the mean maximal inspiratory pressure for the eight patients tested was 40% of predicted, and the mean maximal expiratory pressure was 26% of predicted. Two patients died of respiratory insufficiency. All the patients had lived at least 17 years, while lacking compliant cystine-depleting therapy with oral cysteamine. Seven patients had a conical chest, restricting excursion, and 10 of the 12 patients had evidence of the myopathy that typifies late cystinosis. In fact, the severity of pulmonary disease correlated directly with the severity of myopathy in our group of 12 patients. In contrast, the lung parenchyma was essentially normal, as gauged by chest radiographs and CT scans of the lung. The three patients with nonnephropathic cystinosis displayed entirely normal pulmonary function., Conclusion: The distal myopathy characteristic of nephropathic cystinosis results in an extraparenchymal pattern of restrictive lung disease in adults who have not received long-term cystine depletion. Whether or not oral cysteamine therapy can prevent this complication remains to be determined.

Because cystinotic patients are polyuric and may have severe proteinuria, each of which is a potential risk factor for graft thrombosis, preemptive transplantation for them is questionable. The objectives of this study were to characterize the changes in urine volume and protein excretion at various stages of cystinosis, determine whether there is serologic evidence of hypercoagulability, and review the clinical experience in renal transplantation in cystinotic children. The records of cystinotic patients followed at the Montreal Children's Hospital between 1992 and 1998 were reviewed. Urinary volume, protein excretion, and coagulation markers were collected to determine the glomerular filtration rate (GFR) >50 ml/min/1.73 m2, <20 ml/min/1.73 m2, before and after starting dialysis. In addition, graft failure and graft thrombosis rates were obtained from the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) database. Urinary volume and protein excretion remained elevated throughout different phases of the disease. Coagulation factors were within normal limits for all patients. In the NAPRTCS database there were four thromboses among the 114 patients transplanted cystinotic patients. All these occurred in cadaveric grafts and only one occurred after preemptive transplantation. Despite polyuria and severe proteinuria, children with cystinosis do not appear to be at an increased risk of graft failure or graft thrombosis.

A 16 year-old boy with nephropathic cystinosis and kidney transplantation was successfully treated with rhGH because of growth retardation. After 15 months of rhGH therapy he developed impaired glucose tolerance. Various causes like cystinosis itself, the immunosuppressive therapy with cyclosporine A and cortisone, but rhGH too might have been the responsible factors for that. Treatment with rhGH was initiated again after 4 months of interruption of therapy because no relation between impaired glucose tolerance and GH could be established.

Fourteen families of children with infantile nephropathic cystinosis were evaluated using the Stanford-Binet Intelligence Scale, Fourth Edition [Thorndike et al., 1986: Stanford-Binet Intelligence Scale, Fourth Ed.]. The IQs of 15 children with cystinosis, their 23 sibs and 24 parents were compared in order to evaluate a potential effect of cystinosis on intelligence. Children with cystinosis had a significantly lower mean IQ than their sibs and their parents (P = .001). Thus, even though the mean IQ of the children with cystinosis (94.4 +/- 10) was within the average range, there is evidence that these children have a mild global intellectual deficit relative to their expected IQ based upon the IQs of other relatives. In addition, to a subset of the subjects we administered a measure of scholastic ability, the Wide Range Achievement Test-Revised [Jastak and Wilkinson, 1984: The Wide Range Achievement Test-Revised], which consists of spelling, reading, and arithmetic subtests. The 11 cystinosis subjects scored significantly lower (P = .01) than their 16 sibs and their 14 parents in the area of spelling, whereas they did not significantly differ in their performance in the areas of reading and arithmetic.

Objective: To delineate the clinical characteristics of infantile nephropathic cystinosis in adult patients who have undergone renal transplantation., Design: Case series., Setting: Clinical research unit., Patients: All 36 adult patients with nephropathic cystinosis referred to the National Institutes of Health., Outcome Measures: Longevity, growth, renal allograft survival, visual acuity, endocrine insufficiency, myopathy and swallowing dysfunction, cerebral calcifications, and occupational status., Results: Of the 36 patients, seven were dead, five with functioning allografts. The 1-year and 5-year graft survival rates for 30 cadaveric allografts were 90% and 75%, respectively. The patients' mean height and weight were severely retarded. Five patients were legally blind, and three others had severely impaired vision in one eye. Thirty-one (86%) of 36 patients required thyroid hormone replacement therapy. One third had a distal myopathy, and 21 had moderate to severe swallowing abnormalities. Eight patients had cerebral calcifications on computed tomographic scan. Despite these complications, the sighted patients engaged in a normal variety of occupations. Only 11 patients were receiving adequate cystine-depleting therapy with cysteamine (mercaptamine) or phosphocysteamine., Conclusions: Adult patients with nephropathic cystinosis suffer serious complications of the disease.

Objective: To evaluate reproductive function in patients with cystinosis and in renal transplant recipients without cystinosis., Design: Cross-sectional study., Setting: Clinical Center, National Institutes of Health., Patients: Ten male patients, 15 to 28 years old, with nephropathic cystinosis and renal allografts formed the study group; 11 renal transplant recipients who had a primary renal disorder other than cystinosis and were matched with study patients for age and renal function served as the control group., Measurements: Tanner staging, serum gonadotropin determinations, and testosterone and testosterone-binding globulin assessments. Selected patients also had a human chorionic gonadotropin (HCG) stimulation test, a gonadotropin-releasing hormone (GnRH) stimulation test, and serial sampling for luteinizing hormone (LH)., Main Results: Although testosterone levels were within normal limits in 7 of 10 patients with cystinosis, the mean testosterone level in patients with cystinosis was 11.5 +/- 2.0 nmol/L compared with 24.2 +/- 3.0 nmol/L in control patients (P < 0.005). No patient with cystinosis reached Tanner stage 5 (full pubertal development), whereas 9 of 11 control patients did. Seven of 10 patients with cystinosis had elevations in LH or follicle-stimulating hormone (FSH) levels, suggesting testicular failure. These patients also had normal LH and FSH responses after GnRH stimulation, increased LH pulse frequency, and reduced testosterone response after HCG stimulation. In comparison, only 3 of 11 control patients had minimally elevated gonadotropin levels, and all 11 had normal testosterone levels. Microscopic testicular examination in one patient showed cystine crystals, germinal dysplasia, increased fibrosis, and Leydig cell hyperplasia., Conclusions: Abnormalities in the pituitary-testicular axis are common in male patients with cystinosis. These changes appear to be related to the disease cystinosis and not to treated renal failure per se.

We report on three children who underwent cadaveric renal transplantation and subsequently developed an immunoblastic lymphoma, leading to death in two patients. The development of the lymphoma occurred following a multi-drug immunosuppression regimen ending with monoclonal antilymphocyte (OKT3) treatment for biopsy-proven cellular and vascular acute rejection. These patients represent three of 11 children who received OKT3 treatment for rejection in the last 18 months at this institution. Following the diagnosis of lymphoma, all three patients were treated by transplant nephrectomy, cessation of immunosuppression, and administration of intravenous acyclovir. The first two patients died at 4 days and 4 weeks, respectively, after the definitive diagnosis was made with widespread metastatic disease. The remaining child is a short-term survivor (13 months), free of demonstrable malignancy. Multidrug regimens for immunosuppression have a profound effects on T cell function. These effects, when combined with a primary infection by the Epstein-Barr virus, are implicated in the rapid development of the lymphomas and are responsible for the death of these two children.

In 1989, 22 children (11 boys, 11 girls aged 8-23 years) with nephropathic cystinosis, who had received a total of 28 renal allografts over the previous 14 years, were reviewed. Nineteen were alive, of whom 17 had functioning grafts 5 months to 13 years after transplantation. The mean serum creatinine level in these 17 was 135 mumol/l. Patient and graft survival did not differ from non-cystinotic children. Persistent hypothyroidism was found in 3 patients, transient diabetes mellitus in 1, severely disturbed vision in 1 and brain atrophy in 11. Arterial hypertension was present in 16 patients. Growth retardation was universal, although in 4 patients on cyclosporin A post-transplant catch-up growth occurred. Five patients over 15 years completed puberty. Readjustment in terms of school performance was good but was less good for psychosocial development. None of the patients had ever been treated with cystine-depleting agents; the data will therefore provide a historical control group with which to compare the results from a group treated with these agents.

In an experience of more than 700 kidney transplants, three recipients are known to have had congenital cystinosis. A cadaver kidney transplant in a 10 yr old child with nephropathic cystinosis functioned well for 7 1/2 yr before it was rejected and the graft was free of recurrent cystinosis after that interval. This prolongation of life was associated with marked accumulation of cystine in the patient's thyroid gland, presenting as a mass in the neck. If additional longevity is achieved in this patient, abnormal intracellular cystine accumulation may be expected in other host tissues. Retransplantation was carried out with the father as donor, accepting the possibility of increased cystine levels in the retransplant. This patient's age of 18 yr identifies him as one of the longest known survivors of infantile nephropathic cystinosis.

10 children underwent cadaveric renal transplantation between the ages of 8.0 and 12.5 years for uremia secondary to infantile cystinosis. 6 children are doing well 6-62 months after-transplantation. 3 of the 4 other recipients required a second graft and eventually died of uremia or fulminant viral encephalitis, the other lost her first graft due to accelerated acute rejection and is now on maintenance hemodialysis. No further systemic complications of cystinosis have been observed in the patients with functioning grafts. Our experience confirms that kidney transplantation is the treatment of choice for uremic children with infantile cystinosis.

Twenty-four biopsies of generally cadaveric renal allografts from 20 patients with cystinosis were examined by light, polarization, phase contrast and electron microscopy. Cystine crystals, or cytoplasmic crystalline spaces compatible with cystine, were observed in interstitial cells in 23 of the 24 biopsies and in glomeruli in six. Among the six, crystalline spaces were identified by electron microscopy in cells compatible with macrophages in the mesangium in two, and, in one of the latter, dark, presumably cystine-containing cells were also present in the mesangium. On the premise that cystine-containing cells derive from the host, these findings support the thesis that in man cells of the mononuclear phagocyte system of extrarenal origin may exist in the mesangium. However, in comparison with infiltration of the interstitium, infiltration of the glomerulus by macrophages from extrarenal sources is scant, as studied under conditions of renal transplantation.

Nephropathic cystinosis causes renal death by approximately age 10 years. With increased life span due to kidney transplantation, ten to 25 years of cystine accumulation has resulted in pancreatic complications in individuals with cystinosis. We noted severe hyperglycemia in five posttransplant patients, three of whom remained insulin-dependent diabetics several years after transplant. The clinical findings were not consistent with steroid-dependent or insulin-resistant diabetes. Pancreatic cystine deposition was detected histologically and biochemically on post-mortem examination of two other patients. We conclude that hyperglycemia may be anticipated in the immediate posttransplant period in cystinotic patients and that some patients will require insulin therapy years later. The use of cystine-depleting agents should be considered in posttransplant cystinosis as an attempt to prevent potential damage to the pancreas and other organs from cystine deposition.

Objective: To review the history, basic defect, pathogenesis, clinical manifestations, diagnosis, and treatment of nephropathic cystinosis., Design: Lysosomal membrane transport studies, clinical reports, and a historically controlled 7-year trial of oral cysteamine therapy., Setting: University centers in the United States and Canada., Patients: One hundred forty-eight children, aged 0 to 12, with nephropathic cystinosis before renal transplant, who had renal tubular Fanconi syndrome, failure to grow, corneal cystine crystals, and elevated leukocyte cystine; 34 patients, aged 9 to 29, after transplant, some with visual impairment, corneal erosions, pancreatic dysfunction, or neurologic deterioration., Intervention: Before transplant, replacement of renal losses, and treatment with oral cysteamine (55 mg/kg body weight.d for 1 to 6 years) and topical cysteamine eyedrops (0.1%, 1 drop/h while awake, for 6 months). After transplant, oral cysteamine and symptomatic treatment of late complications., Measurements and Main Results: Untreated patients reached renal failure at age 10. Oral cysteamine lowered leukocyte cystine over 80%, and in patients before transplant, improved growth and preserved renal function (mean creatinine clearance [+/- SE], 0.64 +/- 0.04 mL/s.1.73 m2 [38.5 +/- 2.5 mL/min.1.73 m2] in the cysteamine group compared with 0.50 +/- 0.03 mL/s.1.73 m2 [29.7 +/- 2.0 mL/min.1.73 m2] in controls; 95% CI for the difference, 1.8 to 15.8). Cysteamine eyedrops cleared the corneal crystals of two children less than 2 years old., Conclusions: Cystinosis is a lysosomal storage disease due to impaired transport of cystine out of lysosomes. In young children, growth can be improved and renal deterioration delayed or prevented by oral cysteamine. Nonrenal complications after transplant might be prevented with long-term oral cysteamine.