Living kidney donation from people at risk of nephrolithiasis, with a focus on the genetic forms

A step-by-step, multidisciplinary strategy to maximize the yield of genetic testing in pediatric patients with chronic kidney diseases

BACKGROUND

The use of genetic testing in pediatric patients with chronic kidney diseases (CKD) has increased exponentially in the past few years, particularly with the emergence of novel sequencing techniques. However, the genetic yield remains unexpectedly low in nephrology, with an impact on diagnosis, prognosis and treatment. Moreover, the increasing diversity of genetic testing possibilities can be seen as an obstacle by clinicians, in the absence of a strong background in genetics. Here, we propose a step-by-step, multidisciplinary strategy for the diagnostic evaluation of pediatric patients with CKD, and appropriate genetic test selection to maximize the yield of genetic testing.

METHODS

A total of 126 pediatric patients were enrolled in a retrospective file analysis. Genetic testing techniques used included phenotype-associated next-generation panel sequencing (N = 41), Sanger and SNaPshot sequencing (N = 3) and/or whole exome sequencing (N = 2).

RESULTS

Overall genetic yield reached 63% and genetic testing significantly impacted patient management in 70%. The distribution of kidney diseases among patients was balanced and matched previously described pediatric cohorts in terms of glomerulopathies, tubulopathies and ciliopathies. Genetic analyses led to significant treatment modifications, kidney biopsy sparing and personalized nephroprotection, as well as tailored genetic counseling. Of note, the evaluation of Human Phenotype Ontology term accuracy in the cohort showed that causal mutations were precisely identified in 85% of the patients at most.

CONCLUSION

Here we suggest a step-by-step, multidisciplinary strategy to maximize the yield of genetic testing in pediatric patients with CKD. This approach optimizes patient care while avoiding unnecessary treatments or procedures.

Reasons and effects of the decline of willing related potential living kidney donors

BACKGROUND

Although the availability of related living donors (LDs) provides a better chance for receiving kidney transplantation (KT), the evaluation protocols for LD selection remain a safeguard for the LD's safety. These protocols are variable from one center to another, resulting in variable rates of decline of the potential LDs (PLDs). The decline of willing PLDs may occur at any stage of evaluation, starting from the initial contact and counseling to the day of operation.

AIM

To identify the causes of the decline of PLDs, the predictors of PLD candidacy, and the effect on achieving LDKT.

METHODS

A retrospective study was performed on the willing PLDs who attended our outpatient clinic for kidney donation to their related potential recipients between October 2015 and December 2022. The variables influencing their candidacy rate and the fate of their potential recipients were studied. Two groups of PLDs were compared: Candidate PLDs after a completed evaluation vs non-candidate PLDs with a complete or incomplete evaluation. A multivariate logistic regression was performed to assess the factors contributing to the achievement of PLD candidacy.

RESULTS

Of 321 willing PLDs, 257 PLDs (80.1%) accessed the evaluation to variable extents for 212 potential recipients, with a mean age (range) of 40.5 ± 10.4 (18-65) years, including 169 females (65.8%). The remaining 64 PLDs (19.9%) did not access the evaluation. Only 58 PLDs (18.1%) succeeded in donating, but 199 PDLs (62.0%) were declined; exclusion occurred in 144 PLDs (56.0%) for immunological causes (37.5%), medical causes (54.9%), combined causes (9.7%), and financial causes (2.1%). Regression and release occurred in 55 PLDs (17.1%). The potential recipients with candidate PLDs were not significantly different from those with non-candidate PLDs, except in age (P = 0.041), rates of completed evaluation, and exclusion of PLDs (P < 0.001). There were no factors that independently influenced the rate of PLD candidacy. Most patients who failed to have KT after the decline of their PLDs remained on hemodialysis for 6 mo to 6 years.

CONCLUSION

The rate of decline of willing related PLDs was high due to medical or immunological contraindications, release, or regression of PLDs. It reduced the chances of high percentages of potential recipients in LDKT.

Genetic testing in the diagnosis of chronic kidney disease: recommendations for clinical practice

The overall diagnostic yield of massively parallel sequencing–based tests in patients with chronic kidney disease (CKD) is 30% for paediatric cases and 6–30% for adult cases. These figures should encourage nephrologists to frequently use genetic testing as a diagnostic means for their patients. However, in reality, several barriers appear to hinder the implementation of massively parallel sequencing–based diagnostics in routine clinical practice. In this article we aim to support the nephrologist to overcome these barriers. After a detailed discussion of the general items that are important to genetic testing in nephrology, namely genetic testing modalities and their indications, clinical information needed for high-quality interpretation of genetic tests, the clinical benefit of genetic testing and genetic counselling, we describe each of these items more specifically for the different groups of genetic kidney diseases and for CKD of unknown origin.

Latest developments in living kidney donation

PURPOSE OF REVIEW

Although the first successful kidney transplantation 65 years ago was performed with a living donor kidney, the number of living donor kidney transplantations has increased especially during the last 2 decades. The enlargement of living donor programs was made possible by new modes of living donation and by expansion of the living donor pool. At the same time, the long-term risks of kidney donation have been better delineated. In this review, the latest developments on these topics are summarized.

RECENT FINDINGS

While the results of ABO-incompatible living kidney transplantation are superior to those of deceased donor transplantation, recent meta-analyses show a reduced patient and graft survival as compared with ABO compatible transplantation as well as increased risk of severe infection and bleeding. Kidney paired donation programs can be extended by including compatible couples and by advanced donation, although the latter raises ethical concerns. Living donors appear to have a higher risk of end-stage renal disease and this is especially true for obese donors and probably also for black donors with an APOL1 high-risk genotype. The importance of psychosocial outcomes after living kidney donation is increasingly recognized.

SUMMARY

Living donor kidney transplantation remains the optimal treatment option for patients with end-stage renal disease. To increase the donor pool, a well developed paired kidney donation program and sufficient reimbursement of costs associated with donation are essential ingredients. Other ways of expanding the donor pool, such as ABO-incompatible transplantation, use of higher risk donors, providing donors with financial incentives and advanced donation are associated with medical, ethical and logistical complications. There should be a careful selection and follow-up of living kidney donors with attention for medical consequences as well as for psychosocial outcomes.

Living Kidney Donation in a Type 1 Dent's Disease Patient from His Mother

INTRODUCTION

Dent's disease is a rare X-linked recessive disorder that manifests in childhood or early adulthood and can lead to end-stage renal disease (ESRD). It occurs in males, who are hemizygous. In patients who develop ESRD, a deceased donor kidney transplant cures the disease. Females are obligate carriers of the mutated gene, and some show a mild Dent's disease phenotype. There may be reason for concern when considering a female obligate carrier (i.e., the mother) for kidney donation because of the risk of kidney function deterioration.

CASE PRESENTATION

We describe the first successful kidney transplantation involving a patient with type 1 Dent's disease and ESRD given a kidney by an obligate carrier of the gene mutation, his mother.

CONCLUSIONS

After careful assessment of the female obligate carriers, intrafamilial kidney donation in Dent's disease type 1 is feasible. No deteriorating renal function in the donor was observed.