Trends in kidney transplant outcomes in children and young adults with cystinosis

Cystinosis in Pediatric Renal Transplant Recipients: A Case-Control Study From Kuwait

OBJECTIVES

Cystinosis is the most frequent cause of the inherited renal Fanconi syndrome and is also potentially treatable. In this study, we have reported our single-center experience of the longterm outcomes of kidney transplant in patients with cystinosis.

MATERIALS AND METHODS

Pediatric patients with cystinosis (n = 17) were compared with a matched control group without cystinosis (n = 126). The 2 groups were compared with regard to demographic data, posttransplant complications, and graft and patient outcomes.

RESULTS

Most patients with cystinosis were male teenagers (52.9%) with comparable mean age (12.4 ± 4.1 vs 14 ± 3.1 years) versus the group without cystinosis. The 2 study groups were comparable with regard to type of dialysis, type of donor, blood group, and pretransplant comorbidities (P > .05). Patients with cystinosis received significantly more potent induction therapy (P < 0.05), but both groups were maintained on comparable immunosuppressive regimens (mostly tacrolimus based) (P > .05). Most grafts in both groups displayed immediate graft function. The percentage of patients with cystinosis with primary graft function was significantly higher than the percentage of those patients without cystinosis who had primary graft function (P = .024); this was associated with a relatively lower baseline creatinine level, although this was not significant (P > .05). Posttransplant complications, especially posttransplant diabetes, cytomegalovirus viremia, or BK nephropathy, were comparable (P > .05). Moreover, patient and graft survival rates were similar in the 2 groups (P > .05).

CONCLUSIONS

Under standard immunosuppression, renal transplant and cysteamine therapy were safe with good long-term outcomes in patients with cystinosis. Studies that can include more patients and that have longer follow-up are needed to better understand the nature of this genetic disease and to discover the best treatment options.

Long-Term Care of the Pediatric Kidney Transplant Recipient

Pediatric kidney transplant recipients are distinguished from adult recipients by the need for many decades of graft function, the potential effect of CKD on neurodevelopment, and the changing immune environment of a developing human. The entire life of an individual who receives a transplant as a child is colored by their status as a transplant recipient. Not only must these young recipients negotiate all of the usual challenges of emerging adulthood (transition from school to work, romantic relationships, achieving independence from parents), but they must learn to manage a life-threatening medical condition independently. Regardless of the age at transplantation, graft failure rates are higher during adolescence and young adulthood than at any other age. All pediatric transplant recipients must pass through this high-risk period. Factors contributing to the high graft failure rates in this period include poor adherence to treatment, potentially exacerbated by the transfer of care from pediatric- to adult-oriented care providers, and perhaps an increased potency of the immune response. We describe the characteristics of pediatric kidney transplant recipients, particularly those factors that may influence their care throughout their lives. We also discuss the risks associated with the transition from pediatric- to adult-oriented care and provide some suggestions to optimize the transition to adult-oriented transplant care and long-term outcomes.

Molecular Mechanisms and Treatment Options of Nephropathic Cystinosis

Nephropathic cystinosis is a severe, monogenic systemic disorder that presents early in life and leads to progressive organ damage, particularly affecting the kidneys. It is caused by mutations in the CTNS gene, which encodes the lysosomal transporter cystinosin, resulting in intralysosomal accumulation of cystine. Recent studies demonstrated that the loss of cystinosin is associated with disrupted autophagy dynamics, accumulation of distorted mitochondria, and increased oxidative stress, leading to abnormal proliferation and dysfunction of kidney cells. We discuss these molecular mechanisms driving nephropathic cystinosis. Further, we consider how unravelling molecular mechanisms supports the identification and development of new strategies for cystinosis by the use of small molecules, biologicals, and genetic rescue of the disease in vitro and in vivo.