Nephropathic cystinosis

Cystinosis in Eastern Turkey

BACKGROUND

This study was conducted to investigate CTNS (cystinosin, lysosomal cystine transporter) gene mutations and the clinical spectrum of nephropathic cystinosis among patients diagnosed with the disease in a single center in Turkey.

METHODS

Patients' clinical and laboratory data were extracted from an electronic health registry. Molecular CTNS gene analysis was performed using either next-generation sequencing or Sanger sequencing.

RESULTS

Eleven patients (age range: 1.5-12 years) from nine families were identified. The presenting complaint was growth retardation in seven patients; polydipsia and polyuria in three patients; and vomiting in two patients. At presentation, electrolyte loss was noted in all patients, of which eight patients presented with metabolic acidosis, and three patients presented with metabolic alkalosis. All patients also presented with proteinuria and glucosuria, and four patients developed varying degrees of renal insufficiency, for which peritoneal dialysis was initiated in one patient. Cystine crystals were detected via ocular examination in one patient at presentation. No cystine crystals were detected among patients who underwent bone marrow aspiration. In the CTNS gene, a p.T7FX7 (c.18-21del4bp) mutation was detected in three patients, whereas a p.E227E (c.681 G>A) (homozygous) mutation was detected in eight patients.

CONCLUSIONS

We detected two distinct mutations, p.T7FX7 (c.18-21del4bp) and p.E227E (c.681 G>A) (homozygous), in the CTNS gene in 11 patients with cystinosis from the East Anatolian region of Turkey. Patients with a homozygous c.681 G>A (p.E227E) mutation are more likely to develop chronic renal failure and should be monitored closely, whereas patients with a p.T7FX7 (c.18-21del4bp) mutation have a milder phenotype. Additionally, metabolic alkalosis does not exclude cystinosis, although cystinosis is a cause of proximal renal tubular acidosis.

Cystinosis: the evolution of a treatable disease

Cystinosis is a rare autosomal recessive disorder involving lysosomal storage of the amino acid cystine due to a defect in the membrane transport protein, cystinosin. Since the introduction of kidney transplants and the availability of cystine-depleting medical therapy, this previously fatal disease was transformed into a treatable disorder. Renal allografts and medical therapy targeting the basic metabolic defect have altered the natural hisotry of cystinosis so drastically that patients have a life expectancy extending past 50 years. Consequently, early diagnosis and appropriate therapy are critically important. In this article, we offer a review of the manifestations of cystinosis, including the proximal tubular dysfunction of renal Fanconi syndrome, and discuss the prevention and treatment of the disorder's systemic complications. We focus on the nephropathic forms of cystinosis, aiming to assist nephrologists and other physicians to develop early recognition and appropriate management of cystinosis patients.

Craniofacial and dental findings in cystinosis

OBJECTIVES

Cystinosis is a rare autosomal recessive lysosomal storage disorder with developmental and mineralization anomalies as part of its clinical presentation. The objective of this study was to provide the first systematic assessment of the craniofacial and dental characteristics associated with cystinosis.

STUDY DESIGN

Oral and radiographic evaluations were performed on 73 patients with cystinosis. Analyses of cephalometry (n = 20), taurodontism (n = 47), caries (n = 47), enamel defects (n = 48), soft tissue anomalies (n = 48), and dental age (n = 41) were performed on the cystinosis group, and compared with age- and sex-comparable controls or standards.

RESULTS

Cystinosis patients manifested relative mandibular deficiency, an increased facial height, and a reduced airway space. Taurodontism and enamel defects were significantly more prevalent in cystinosis patients compared with controls (P < 0.0001 and P = 0.027, respectively). Children (aged <15 years) with cystinosis also demonstrated a significant delay, of almost 9 months, of their dental development (P < 0.001).

CONCLUSION

Novel craniofacial and dental features are associated with cystinosis. Craniofacial deficiencies may influence the swallowing and respiratory complications seen in cystinosis. Renal pathology and associated mineral imbalance may explain the dental root and enamel anomalies found in cystinosis patients; the developmental delays in cystinosis include delayed dental formation.

Long-term tracking of neurological complications of encephalopathy and myopathy in a patient with nephropathic cystinosis: a case report and review of the literature

Introduction

Cystinosis is a hereditary storage disease resulting in intracellular accumulation of cystine and crystal formation that causes deterioration of the function of many organs. The major clinical symptom is renal failure, which progresses and necessitates renal transplantation at the beginning of the second decade of life. Encephalopathy and distal myopathy are important neurological long-term complications with a major impact on the quality of life of these patients. Application of cysteamine is the only specific therapy available; it decreases the intracellular cystine level and delays or may even prevent the failure of organ functions.

Case presentation

We present the case of a 38-year-old woman with cystinosis and the long-term tracking of her neurological symptoms under cysteamine treatment.

Conclusion

This case report describes a long observation period of neurological complications in a person with cystinosis who had strikingly different courses of encephalopathy and myopathy while on cysteamine treatment. Although encephalopathy was initially suspected, this did not develop, but distal myopathy progressed continuously despite specific therapy.

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.

Intravenous delivery of cysteamine for the treatment of cystinosis: association with hepatotoxicity

Nephropathic cystinosis is a lysosomal storage disorder, which, if untreated, results in renal failure by age 10 years. Oral cysteamine has been shown to preserve renal function in these patients. In this study, a 2-year-old girl with nephropathic cystinosis and severe gastrointestinal dysmotility was treated with intravenous (i.v.) administration of cysteamine hydrochloride (HCl). This is only the second report of long-term i.v. cysteamine therapy for nephropathic cystinosis. Unlike the treatment in the previous case, however, treatment in our patient was limited by liver toxicity.

Cystinosis as a cause of noncirrhotic portal hypertension

Cystinosis is a rare autosomal recessive storage disorder, characterized by the abnormal accumulation of cystine in cellular lysosomes. This accumulation, which can occur in any organ system, leads to crystallization of trapped cystine and ultimately cellular death. Hepatic manifestations of Cystinosis although rare, have been described in the literature. However, to our knowledge, only one other case of non-cirrhotic portal hypertension secondary to cystine accumulation in Kupffer cells has been reported. In this case and ours, portal hypertension was found in the absence of bridging fibrosis. Furthermore, in our case, for the majority of the patient's course, hepatic synthetic function remained normal. Cysteamine is therapeutic in this disorder, and can lead to significant removal of cystine, and thus to reversibility of disease, however, it requires high doses and must be taken regularly. Porto-systemic shunting in combination with aggressive medical therapy could potentially benefit patients who develop non-cirrhotic portal hypertension in this clinical setting.

A new mutation in two siblings with cystinosis presenting with Bartter syndrome

Nephropathic cystinosis is a severe autosomal recessive inherited metabolic disease characterized by accumulation of free cystine in lysosomes. Cystinosis can lead to renal failure and multiorgan impairment. Only five cases of cystinosis with associated Bartter syndrome are reported in the literature, and no genetic evaluation has been reported. We describe two siblings with nephropathic cystinosis presenting with features of Bartter syndrome and their genetic pattern.