Multidisciplinary approach for patients with nephropathic cystinosis: model for care in a rare and chronic renal disease

Quality of life and mental health status in caregivers of pediatric patients with nephropathic cystinosis

There are few studies assessing psychological burden and quality of life (QoL) in caregivers of pediatric patients with nephropathic cystinosis, a severe chronic disease. This observational, single-center study aimed to explore the levels of anxiety, depression, care burden, and QoL status in caregivers of patients with nephropathic cystinosis. The Hospital Anxiety and Depression Scale (HADS), the Zarit Caregiver Burden Scale, and the Short Form-36 (SF-36) were administered to caregivers of pediatric patients with nephropathic cystinosis. Nine caregivers of pediatric patients with nephropathic cystinosis participated in the study (6 boys and 3 girls; mean age, 12.6 ± 4.2 years). All participating caregivers were the patient's mothers. Of the 9 caregivers, 6 showed anxiety/depression and 4 severe care burden. Overall, SF-36 QoL domains with a worse perception by caregivers were 'general health' and 'health change over time'. Mothers without depression/anxiety and low care burden had better QoL perception (p = 0.02). All caregivers with high care burden showed anxiety/depression. In our study cohort, caregivers of pediatric patients with nephropathic cystinosis showed high levels of anxiety/depression, high care burden, and impaired QoL, highlighting the importance of detecting psycho-social issues to implement strategies that relieve family stress and improve coping strategies.

Inherited Fanconi syndrome

BACKGROUND

Fanconi-Debré-de Toni syndrome (also known as Fanconi renotubular syndrome, or FRST) profoundly increased the understanding of the functions of the proximal convoluted tubule (PCT) and provided important insights into the pathophysiology of several kidney diseases and drug toxicities.

DATA SOURCES

We searched Pubmed and Scopus databases to find relevant articles about FRST. This review article focuses on the physiology of the PCT, as well as on the physiopathology of FRST in children, its diagnosis, and treatment.

RESULTS

FRST encompasses a wide variety of inherited and acquired PCT alterations that lead to impairment of PCT reabsorption. In children, FRST often presents as a secondary feature of systemic disorders that impair energy supply, such as Lowe's syndrome, Dent's disease, cystinosis, hereditary fructose intolerance, galactosemia, tyrosinemia, Alport syndrome, and Wilson's disease. Although rare, congenital causes of FRST greatly impact the morbidity and mortality of patients and impose diagnostic challenges. Furthermore, its treatment is diverse and considers the ability of the clinician to identify the correct etiology of the disease.

CONCLUSION

The early diagnosis and treatment of pediatric patients with FRST improve the prognosis and the quality of life.

CTNS mRNA molecular analysis revealed a novel mutation in a child with infantile nephropathic cystinosis: a case report

BACKGROUND

Cystinosis is an autosomal recessive lysosomal storage disorder characterized by accumulation of cystine in lysosomes throughout the body. Cystinosis is caused by mutations in the CTNS gene that encodes the lysosomal cystine carrier protein cystinosin. CTNS mutations result in either complete absence or reduced cystine transporting function of the protein. The diagnosis of nephropathic cystinosis is generally based on measuring leukocyte cystine level, demonstration of corneal cystine crystals by the slit lamp examination and confirmed by genetic analysis of the CTNS gene.

CASE PRESENTATION

A boy born to consanguineous Caucasian parents had the characteristic clinical features of the infantile nephropathic cystinosis including renal Fanconi syndrome (polydipsia/polyuria, metabolic acidosis, hypokalemia, hypophosphatemia, low molecular weight proteinuria, glycosuria, cystine crystals in the cornea) and elevated WBC cystine levels. Initially we performed RFLP analysis of the common in the Northern European population 57-kb deletion of proband's DNA, then a direct Sanger sequencing which revealed no mutations in the coding part of the CTNS gene. To confirm the diagnosis we performed RT-PCR analysis of total RNA obtained from patient-derived fibroblasts in combination with cDNA sequencing. This revealed the skipping of exon 4 and exon 5 in the CTNS in our patient. Therefore, we detected a novel 9-kb homozygous deletion in the CTNS gene at genomic DNA level, spanning region from intron 3 to intron 5. In order to identify the inheritance pattern of the deletion we analyzed DNA of proband's mother and father. Both parents were found to be heterozygous carriers of the CTNS mutation.

CONCLUSIONS

Analysis of CTNS gene transcript allowed to identify a large homozygous deletion in the patient with infantile nephropathic cystinosis. Mutational detection at RNA level may be an efficient tool to establish the genetic defect in some cystinosis patients.