Late symptoms in infantile cystinosis

Neurologic involvement in cystinosis: Focus on brain lesions and new evidence of four-repeat (4R-) Tau immunoreactivity

Nephropathic cystinosis is a rare autosomal recessive storage disorder caused by CTNS gene mutations, leading to autophagy-lysosomal pathway impairment and cystine crystals accumulation. Neurologic involvement is highly variable and includes both neurodevelopmental and neurodegenerative disturbances, as well as focal neurologic deficits. By presenting longitudinal data of a 28-year-old patient with a large infratentorial lesion, we summarized the pathology, clinical and imaging features of neurological involvement in cystinosis patients. Brain damage in form of cystinosis-related cerebral lesions occurs in advanced disease phases and is characterized by the accumulation of cystine crystals, subsequent inflammation with vasculitis-like features, necrosis, and calcification. Epilepsy is a frequent comorbidity in affected individuals. Steroids might play a role in the symptomatic treatment of "stroke-like" episodes due to edematous-inflammatory lesions, but probably do not change the overall prognosis. Lifelong compliance to depleting therapy with cysteamine still represents the main therapeutic option. However, consequences of CTNS gene defects are not restricted to cystine accumulation. New evidence of four-repeat (4R-) Tau immunoreactivity suggests concurrent progressive neurodegeneration in cystinosis patients, highlighting the need of innovative therapeutic strategies, and shedding light on the crosstalk between proteinopathies and autophagy-lysosomal system defects. Eventually, emerging easily accessible biomarkers such as serum neurofilament light chains (NfL) might detect subclinical neurologic involvement in cystinosis patients.

Nephropathic cystinosis: an update

PURPOSE OF REVIEW

Over the past few decades, cystinosis, a rare lysosomal storage disorder, has evolved into a treatable metabolic disease. The increasing understanding of its pathophysiology has made cystinosis a prototype disease, delivering new insights into several fundamental biochemical and cellular processes.

RECENT FINDINGS

In this review, we aim to provide an overview of the latest advances in the pathogenetic, clinical, and therapeutic aspects of cystinosis.

SUMMARY

The development of alternative therapeutic monitoring strategies and new systemic and ocular cysteamine formulations might improve outcome of cystinosis patients in the near future. With the dawn of stem cell based therapy and new emerging gene-editing technologies, novel tools have become available in the search for a cure for cystinosis.

Pancytopenia in a patient with cystinosis secondary to myelosuppression from cystine crystal deposition: a case report

Introduction

Cystinosis is a rare metabolic genetic disorder caused by a mutation in the cystinosin lysosomal cystine transporter gene. Clinically, it is characterized by systemic accumulation of cystine crystals in tissues causing end-organ dysfunction in the kidney, eyes, muscles, and other organs in the body. In very rare cases, it can also involve the bone marrow and the resulting cystine crystal deposition can cause myelosuppression leading to pancytopenia.

Case presentation

Here we report the case of a 26-year-old white woman with cystinosis and other complex medical comorbidities who developed pancytopenia. She was worked up extensively and ruled out for common causes of pancytopenia (infectious disorders, vitamin deficiencies secondary to gastrointestinal malabsorption, rheumatologic, and hematologic disorders). On bone marrow biopsy she was found to have extensive deposits of cystine crystals, which was thought to be the cause of her myelosuppression leading to her pancytopenia. As a result, by treating her underlying cystinosis more aggressively we were able to observe an improvement in her pancytopenia a few months afterwards.

Conclusions

Pancytopenia secondary to myelosuppression from cystine crystal deposition in the bone marrow is a very rare complication that has been reported in only a handful of case reports. This case illustrates the importance of keeping a broad differential diagnosis and systematically ruling out common causes of pancytopenia. It also demonstrates the importance of bone marrow biopsies in the evaluation of unexplained pancytopenia.

Excellent long-term outcome of renal transplantation in cystinosis patients

Background

Cystinosis is a rare lysosomal disorder leading to end stage renal disease in more than 90 % of patients before 20 years of age. Data about safety and efficiency of renal transplantation in patients with cystinosis is scarce. We evaluated long-term outcomes of renal transplantation in adult patients with cystinosis.

Methods

Data of renal transplantation (n = 31) in 30 adult patients with cystinosis in 5 French university transplant centers between 1980 and 2013 were retrospectively analyzed. A control cohort of 93 patients was matched for age, graft date, living/deceased donor status and transplant center.

Results

Median age at transplantation was 20.4 years (7–36.5). At transplantation, all patients with cystinosis had corneal cystine deposits, 3 had diabetes and 7 had hypothyroidism. Graft survival was better in patients with cystinosis than in control patients (p = 0.013). Multivariate analysis confirmed that cystinosis was an independent protective factor for graft survival (Hazard Ratio (HR) 0.11; CI95 [0.02-0.61]). Specific complications of cystinosis occurred during follow up: diabetes mellitus (n = 4), hypothyroidism (n = 1), liver involvement (n = 1), neurologic involvement (n = 2). Proportion of post-transplant diabetes mellitus (PTDM) was not statistically different in cystinosis group compared to control group: 4 (13.0 %) compared to 5 (5.0 %), respectively (p = 0.25), with no differences regarding calcineurin inhibitors and steroids treatments during follow-up.

Conclusions

Renal transplantation appears to be safe with excellent long-term outcomes in patients with cystinosis. These patients may receive standard immunosuppressive regimens with steroids and calcineurin inhibitors.

Nephropathic cystinosis: an international consensus document

Cystinosis is caused by mutations in the CTNS gene (17p13.2), which encodes for a lysosomal cystine/proton symporter termed cystinosin. It is the most common cause of inherited renal Fanconi syndrome in young children. Because of its rarity, the diagnosis and specific treatment of cystinosis are frequently delayed, which has a significant impact on the overall prognosis. In this document, we have summarized expert opinions on several aspects of the disease to improve knowledge and provide guidance for diagnosis and treatment.

Executive function in nephropathic cystinosis

OBJECTIVE

We studied executive function (EF) in children and adolescents with cystinosis.

BACKGROUND

Cystinosis is a genetic metabolic disorder in which the amino acid cystine accumulates in all organs of the body, including the brain. Previous research has shown that individuals with cystinosis have visuospatial deficits, but normal intelligence and intact verbal abilities. Better understanding of the behavioral phenotype associated with cystinosis could have important implications for treatment.

METHODS

Twenty-eight children with cystinosis and 24 control participants (age range 8 to 17 years) underwent selected Delis-Kaplan executive function system tests for neuropsychological assessment of EF, and the participants' parents completed the behavior rating inventory of executive function.

RESULTS

Participants with cystinosis performed significantly more poorly than controls on all Delis-Kaplan Executive Function System indices examined and on the behavior rating inventory of executive function metacognition index and global executive composite.

CONCLUSIONS

EF is an area of potential risk in cystinosis. Our data have implications not only for the function of affected children and adolescents in school and daily life, but also for disease management and treatment adherence. Our findings can aid in the design and implementation of interventions and lead to a greater understanding of brain-behavior relationships in cystinosis.

Cysteamine therapy delays the progression of nephropathic cystinosis in late adolescents and adults

Nephropathic cystinosis is a multisystem autosomal recessive disease caused by cystine accumulation, which is usually treated by oral cysteamine. In order to determine long-term effects of this therapy, we enrolled 86 adult patients (mean age 26.7 years) diagnosed with nephropathic cystinosis, 75 of whom received cysteamine. Therapy was initiated at a mean age of 9.9 years with a mean duration of 17.4 years. By last follow-up, 78 patients had end-stage renal disease (mean age 11.1 years), 62 had hypothyroidism (mean age 13.4), 48 developed diabetes (mean age 17.1 years), and 32 had neuromuscular disorders (mean age 23.3 years). Initiating cysteamine therapy before 5 years of age significantly decreased the incidence and delayed the onset of end-stage renal disease, and significantly delayed the onset of hypothyroidism, diabetes, and neuromuscular disorders. The development of diabetes and hypothyroidism was still significantly delayed, however, in patients in whom therapy was initiated after 5 years of age, compared with untreated patients. The life expectancy was significantly improved in cysteamine-treated versus untreated patients. Thus, cysteamine decreases and delays the onset of complications and improves life expectancy in cystinosis. Hence, cysteamine therapy should be introduced as early as possible during childhood and maintained lifelong.

Radiotherapy-induced hyperthyroidism in a cystinotic kidney transplant patient with Hodgkin lymphoma

Hypothyroidism is a well-known complication of cystinosis. PTLD incidence in pediatric renal transplant population ranges between 1 and 4.5%. We describe the case of a young cystinotic patient who developed hyperthyroidism after radiotherapy for Hodgkin lymphoma. He is a 23-yr-old male who was diagnosed with cystinosis at the age of two. He developed renal failure and other extrarenal complications but never presented hypothyroidism. At the age of 12, he received a successful kidney transplant from a cadaveric donor. Two yr later, EBV-positive Hodgkin lymphoma was diagnosed and chemotherapy and radiotherapy were administered. He achieved remission. Eight yr later, autoimmune hyperthyroidism secondary to previous radiation was detected, and he slowly became symptomatic. Clinical symptoms and laboratory data spontaneously normalized. This is the first case of a cystinotic patient developing hyperthyroidism. Thyroid disorders, especially hypothyroidism, have been reported in association with neck irradiation. Hypothyroidism would have been considered to be a late complication of cystinosis and not a consequence of radiotherapy. Thyroid hormones, clinical examination, and history evaluation for thyroid dysfunction should be periodically monitored after neck radiotherapy. The thyroid should always be excluded from the irradiation fields. Multidisciplinary interaction in difficult cases should be encouraged.

Nephropathic cystinosis: late complications of a multisystemic disease

Cystinosis is a rare autosomal recessive disorder due to impaired transport of cystine out of cellular lysosomes. Its estimated incidence is 1 in 100,000 live births. End-stage renal disease (ESRD) is the most prominent feature of cystinosis and, along with dehydration and electrolyte imbalance due to renal tubular Fanconi syndrome, has accounted for the bulk of deaths from this disorder. Prior to renal transplantation and cystine-depleting therapy with cysteamine for children with nephropathic cystinosis, their lifespan was approximately 10 years. Now, cystinotic patients have survived through their fifth decade, but the unremitting accumulation of cystine has created significant non-renal morbidity and mortality. In this article we review the classic presentation of nephropathic cystinosis and the natural history, diagnosis, and treatment of the disorder's systemic involvement. We also emphasize the role of oral cysteamine therapy in preventing the late complications of cystinosis.

Hematological manifestations of nephropathic cystinosis

Pancytopenia is an uncommon manifestation of cystinosis, a congenital lysosomal storage disease. We describe a 34-year-old patient with nephropathic cystinosis with multisystem involvement who developed progressive bone marrow failure after renal transplantation. Bone marrow examination demonstrated widespread deposition of cystine crystals in histiocytes and in the background. We review the literature on the hematologic manifestations of cystinosis and discuss the available treatment options for patients with bone marrow failure secondary to cystine accumulation. The availability of effective oral therapy and the limited activity of hematopoietic growth factors in these patients highlight the importance of bone marrow examination early in the evaluation of cystinosis patients with abnormal blood counts.

Ophthalmic manifestations and histopathology of infantile nephropathic cystinosis: report of a case and review of the literature

Cystinosis is a rare autosomal recessive metabolic disorder characterized by the intracellular accumulation of cystine, the disulfide of the amino acid cysteine, in many organs and tissues. Infantile nephropathic cystinosis is the most severe phenotype. Corneal crystal accumulation and pigmentary retinopathy were originally the most commonly described ophthalmic manifestations, but successful kidney transplantation significantly changed the natural history of the disease. As cystinosis patients now live longer, long-term complications in extrarenal tissues, including the eye, have become apparent. A case of an adult patient with infantile nephropathic cystinosis is reported. He presented with many long-term ocular complications of cystinosis. After 4 years of follow-up, the patient died from sepsis. Pathology of the phthisical eyes demonstrated numerous electron-transparent polygonal spaces, bounded by single membrane, in corneal cells, retinal pigment epithelial cells, and even choroidal endothelial cells. The ophthalmic manifestations and pathology of infantile nephropathic cystinosis are discussed and reviewed in light of the current report and other cases in the literature.

Nodular regenerative hyperplasia and severe portal hypertension in cystinosis

BACKGROUND & AIMS

Cystinosis is a rare autosomal-recessive disorder characterized by the intralysosomal accumulation of cystine, which is responsible for widespread tissue destruction. Liver biopsy specimens of patients with cystinosis show cystine crystal formation in Kupffer cells. However, significant liver disease and portal hypertension is not a common complication of cystinosis. We report the case histories of 2 young men with poorly treated nephropathic cystinosis who developed noncirrhotic portal hypertension with evidence of nodular regenerative hyperplasia (NRH).

METHODS

Liver biopsy examinations, upper and lower endoscopy with biopsy examination, imaging studies, venous pressure measurements, and laboratory investigations were used to evaluate the causes of the liver disease and portal hypertension.

RESULTS

Histologic examination of liver biopsy specimens from both patients showed changes characteristic of NRH with portal hypertension documented by measurement of pressure gradients. In addition, endoscopy in the first patient showed varices and portal hypertensive gastropathy.

CONCLUSIONS

NRH was confirmed by histologic examination of the liver in both patients and is the likely cause of their portal hypertension. NRH may represent a rare, late complication of cystinosis, although the mechanism remains undefined.

Impaired activity of the gamma-glutamyl cycle in nephropathic cystinosis fibroblasts

Cystinotic patients have been shown to excrete in their urine high levels of pyroglutamate, an intermediate metabolite of the adenosine triphosphate (ATP)-dependent gamma-glutamyl cycle, which is responsible for glutathione (GSH) synthesis. Human fibroblasts were used to study the mechanisms leading to pyroglutamate accumulation in nephropathic cystinosis (NC). We show that inhibition of ATP synthesis caused a marked intracellular accumulation of pyroglutamate, reflecting decreased GSH synthesis. Despite similar degrees of ATP depletion, pyroglutamate increased more in cystinotic fibroblasts than in controls, while GSH decreased to lower levels. In addition, cystinotic cells exposed to oxidative stress (hydrogen peroxide) were unable to increase their GSH concentration above baseline. These results could not be attributed to differences in mitochondrial oxidative activity or to increased apoptotic cell death. Together, these results support the hypothesis that cysteine derived from lysosomal cystine efflux limits the activity of the gamma-glutamyl cycle and GSH synthesis.

Delayed puberty in chronic illness

Delayed puberty can be defined as the lack of pubertal development at an age of 2 SD above the mean, which corresponds to an age of approximately 14 years for males and 13 years for females, taking both sex and ethnic origin into consideration. Its incidence associated with chronic illnesses is unknown; however, its clinical importance is relevant due to the larger percentage of patients with chronic disorders surviving until the age of puberty. Virtually every child with any chronic disease could present with delayed puberty (due to recurrent infections, immunodeficiency, gastrointestinal disease, renal disturbances, respiratory illnesses, chronic anaemia, endocrine disease, eating disorders, exercise and a number of miscellaneous abnormalities). Pubertal delay associated with chronic illness is accompanied by a delay in growth and the pubertal growth spurt. The degree to which growth and pubertal development are affected in chronic illness depends upon the type of disease and individual factors, as well as on the age at illness onset, its duration and severity. The earlier its onset and the longer and more severe the illness, the greater the repercussions on growth and pubertal development. The mechanism that trigger the start of physiological puberty remain unknown. Although malnutrition is probably the most important mechanism responsible for delayed puberty, emotional deprivation, toxic substances, stress and the side effects of chronic therapy, among others, have been implicated in the pathophysiology of delayed puberty. Therefore, early diagnosis is essential and appropriate and specific therapy fundamental.

Long-term treatment with growth hormone in short children with nephropathic cystinosis

OBJECTIVE

The objective was to assess the efficacy and safety of growth hormone (GH) treatment in severely growth retarded children with nephropathic cystinosis during conservative treatment and during renal replacement therapy.

STUDY DESIGN

The design was an open-labeled prospective trial with a run-in period of 1 year.

RESULTS

A total of 74 children with cystinosis (age 3.0 to 18 years) were treated with GH over a mean period of 3.1 years (range 1 to 10 years); 52 patients were receiving conservative treatment (mean age 7.1 years), 7 were receiving dialysis (12.5 years), and 15 had received a renal transplant (14.8 years). The mean standardized height (SD score) was -4.0 in the conservative treatment group, -4.4 in the dialysis group, and -4.9 in the renal transplant group. During the first treatment year, height velocity doubled in the conservative treatment group, increased by 80% in the dialysis group, and increased by 45% in renal transplant group. Within 3 years the height SD score increased by +1.6 (P <.001) in prepubertal patients receiving conservative treatment, and percentile parallel growth was maintained thereafter. These effects of GH were less expressed in peripubertal patients receiving renal replacement therapy. No major side effects were observed.

CONCLUSION

Long-term GH treatment is safe and effective in young children with nephropathic cystinosis. GH treatment should be started early in the course of the disease if adequate nutrition and cysteamine treatment do not prevent growth retardation.

Treatment with recombinant human growth hormone in short children with nephropathic cystinosis: no evidence for increased deterioration rate of renal function. The European Study Group on Growth Hormone Treatment in Short Children with Nephropathic Cystinosis

To evaluate the effect of long-term treatment with recombinant human GH (rhGH) on renal function in short children with nephropathic cystinosis with and without concomitant cysteamine treatment, 36 growth-retarded children with nephropathic cystinosis (age 7.3+/-2.7 y; creatinine clearance [C(CR)] 50+/-27 mL (min x 1.73 m2)(-1) were treated with 1 IU rhGH/kg/wk for up to 5 y. The rise in serum creatinine before and during rhGH treatment was compared with that in a historical control group of cystinotic patients. The effect of concomitant cysteamine treatment on the evolution of renal function before and after the start of rhGH was evaluated separately in patients without (group A) and with cysteamine treatment (group B). The decline of C(CR) was also compared with that in noncystinotic patients with chronic renal failure with and without rhGH treatment. At study entry, serum creatinine values in group A were similar to those in the historical controls, whereas group B had significantly lower serum creatinine values. Treatment with rhGH did not accelerate the rise in creatinine independently of cysteamine treatment. There were no significant differences in the mean decline of C(CR) per year in cystinotic compared with noncystinotic patients with chronic renal failure with or without rhGH treatment. rhGH therapy for up to 5 y does not accelerate the deterioration of renal function. This justifies the continuation of controlled studies of rhGH treatment in these patients. The study also provides further evidence that cysteamine therapy reduces the progression of renal failure in children with cystinosis.

A cost-effectiveness analysis of the orphan drug cysteamine in the treatment of infantile cystinosis

OBJECTIVE

Cysteamine is a recently licensed orphan drug used to treat the inherited metabolic disease cystinosis. The drug delays the onset of renal failure in cystinotic patients and may provide many other significant health benefits. This study examined the cost-effectiveness of the administration of cysteamine to cystinotic patients prior to end-stage renal disease (ESRD).

METHOD

Decision-tree analysis and cost-effectiveness analysis. Cost data were estimated from current clinical charges and Medicare public-access reports. Life expectancy outcomes were derived from both published and unpublished clinical studies and from the U.S. Renal Data System.

RESULTS

Cysteamine therapy can extend the life of kidneys and delay renal transplantation, thereby increasing life expectancy for patients with cystinosis. Patients receiving cysteamine therapy prior to renal failure have lifetime-treatment drug costs of $234,000, in comparison with $238,000 for those who are not medicated. Costs of cysteamine therapy are offset by savings associated with delaying transplantation and costs of dialysis.

CONCLUSIONS

Use of the orphan drug cysteamine both improves health outcomes and reduces health care costs for patients with cystinosis.

Clinical polymorphism of cystinosis encephalopathy. Results of treatment with cysteamine

Of the 26 cystinotic patients over 19 years of age followed in our institution, 7 developed CNS complications at a mean age of 23 years. Two forms were observed. The first, associating cerebellar and pyramidal signs, mental deterioration and finally pseudo-bulbar palsy, may be called cystinosis encephalopathy. The other form resembled a stroke-like episode with coma and hemiplegia or milder symptoms. Hydrocephalus was rare and not associated with clinical symptoms in this series. Cysteamine was administered for longer than 6 months to 4 of the patients with encephalopathy. Two had an almost complete disappearance of their symptoms including the gross abnormalities of MR imaging in one; one improved partially and remained stable, and one continued to deteriorate but was suspected of non-compliance. These results suggest that cysteamine may be an effective treatment of cystinosis encephalopathy and encourage prescription of this drug in cystinosis in order to prevent this complication.

Cystinosis and gingival hyperplasia: demonstration of cystine crystals in gingival tissue and unusual aspects of management

A patient with nephropathic cystinosis developed gingival hyperplasia secondary to cyclosporine-A therapy for his renal allograft. The typical crystals described on electron microscopic examination of other organs of patients with cystinosis were seen in the resected gingiva of this patient. These crystals have not been previously described in this location. Unusual aspects of the management of this patient are discussed.

Growth and pubertal development in nephropathic cystinosis

In a retrospective investigation growth and pubertal development were evaluated in 30 patients with nephropathic cystinosis. Growth was investigated during the stage of chronic renal insufficiency as well as after successful kidney transplantation and growth rates were related to kidney function. Pubertal development was evaluated in 17 patients between 12 and 25 years of age. Prepubertal growth rates were stable in a range between -2 and -3 height velocity SDS as long as glomerular filtration rate was above 20ml/min per 1.73m2. A decrease in glomerular filtration rate below this threshold was followed by further decrease in height velocity. After kidney transplantation a significant catch-up growth was seen if immunosuppression was performed with cyclosporine A and low dose prednisolone. This did not occur if conventional therapy with azathioprine and high-dose prednisolone was used. Onset of puberty was delayed in all patients. Gonadotropin and oestradiol levels in female patients showed normal fluctuations according to ovulatory cycles. In male patients after puberty there was an increase in gonadotropin levels above the normal range for adult men while testosterone levels remained in the low normal range. These results indicate that adult men with nephropathic cystinosis may develop hypergonadotropic hypogonadism.

Renal transplantation for infantile cystinosis: long-term follow-up

Renal transplantation for infantile cystinosis corrects renal failure and prolongs survival. However, after transplantation, the disease may develop in the allograft and continue to progress in nonrenal organs. We studied seven children (6 boys, 1 girl) with infantile cystinosis who received 11 renal transplants (3 cadaver, 8 living-related) between May 1969 and December 1986. The age at transplant ranged from 6 to 12 years (mean, 9.1 years). Four children received second renal transplants at a mean age of 17 years (range, 16 to 22 years). The mean period of follow-up was 138 +/- 47 months. Three children received cysteamine therapy prior to transplantation. Nonrenal complications of infantile cystinosis present before transplantation were photophobia (n = 3), corneal crystals (n = 5), hypothyroidism (n = 1), rickets (n = 6), and short stature (n = 7). Graft and patient survival did not differ from controls matched for the time of transplantation. Two patients died (1 pneumococcal sepsis, 1 respiratory failure due to pulmonary fibrosis) with functioning grafts 5 and 14 years posttransplant. Complications that developed posttransplant included photophobia (n = 1), corneal crystals (n = 2), hypothyroidism (n = 4), polyneuropathy (n = 1), pulmonary fibrosis (n = 1), abnormal electroencephalogram without clinical seizures (n = 1), bladder stones (n = 1), and diabetes mellitus (n = 2). One patient received a corneal transplant. All seven children failed to show improvement in growth following transplantation. Cystine crystals are present in graft-infiltrating cells, but do not seem to affect kidney allograft function.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal transplantation in 22 children with nephropathic cystinosis

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.