Testing for High-Risk APOL1 Alleles in Potential Living Kidney Donors

Development of a culturally targeted chatbot to inform living kidney donor candidates of African ancestry about APOL1 genetic testing: a mixed methods study

Clinical chatbots are increasingly used to help integrate genetic testing into clinical contexts, but no chatbot exists for Apolipoprotein L1 (APOL1) genetic testing of living kidney donor (LKD) candidates of African ancestry. Our study aimed to culturally adapt and assess perceptions of the Gia® chatbot to help integrate APOL1 testing into LKD evaluation. Ten focus groups and post-focus group surveys were conducted with 54 LKDs, community members, and kidney transplant recipients of African ancestry. Data were analyzed through thematic analysis and descriptive statistics. Key themes about making Gia culturally targeted included ensuring: (1) transparency by providing Black LKDs' testimonials, explaining patient privacy and confidentiality protections, and explaining how genetic testing can help LKD evaluation; (2) content is informative by educating Black LKDs about APOL1 testing instead of aiming to convince them to undergo testing, presenting statistics, and describing how genetic discrimination is legally prevented; and (3) content avoids stigma about living donation in the Black community. Most agreed Gia was neutral and unbiased (82%), trustworthy (82%), and words, phrases, and expressions were familiar to the intended audience (85%). Our culturally adapted APOL1 Gia chatbot was well regarded. Future research should assess how this chatbot could supplement provider discussion prior to genetic testing to scale APOL1 counseling and testing for LKD candidate clinical evaluation.

Implementation of a culturally competent APOL1 genetic testing programme into living donor evaluation: A two-site, non-randomised, pre-post trial design

INTRODUCTION

While living donor (LD) kidney transplantation is the optimal treatment for patients with kidney failure, LDs assume a higher risk of future kidney failure themselves. LDs of African ancestry have an even greater risk of kidney failure post-donation than White LDs. Because evidence suggests that Apolipoprotein L1 (APOL1) risk variants contribute to this greater risk, transplant nephrologists are increasingly using APOL1 genetic testing to evaluate LD candidates of African ancestry. However, nephrologists do not consistently perform genetic counselling with LD candidates about APOL1 due to a lack of knowledge and skill in counselling. Without proper counselling, APOL1 testing will magnify LD candidates' decisional conflict about donating, jeopardising their informed consent. Given cultural concerns about genetic testing among people of African ancestry, protecting LD candidates' safety is essential to improve informed decisions about donating. Clinical 'chatbots', mobile apps that provide genetic information to patients, can improve informed treatment decisions. No chatbot on APOL1 is available and no nephrologist training programmes are available to provide culturally competent counselling to LDs about APOL1. Given the shortage of genetic counsellors, increasing nephrologists' genetic literacy is critical to integrating genetic testing into practice.

METHODS AND ANALYSIS

Using a non-randomised, pre-post trial design in two transplant centres (Chicago, IL, and Washington, DC), we will evaluate the effectiveness of culturally competent APOL1 testing, chatbot and counselling on LD candidates' decisional conflict about donating, preparedness for decision-making, willingness to donate and satisfaction with informed consent and longitudinally evaluate the implementation of this intervention into clinical practice using the Reach, Effectiveness, Adoption, Implementation and Maintenance framework.

ETHICS AND DISSEMINATION

This study will create a model for APOL1 testing of LDs of African ancestry, which can be implemented nationally via implementation science approaches. APOL1 will serve as a model for integrating culturally competent genetic testing into transplant and other practices to improve informed consent. This study involves human participants and was approved by Northwestern University IRB (STU00214038). Participants gave informed consent to participate in the study before taking part.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04910867. Registered 8 May 2021, https://register.

CLINICALTRIALS

gov/prs/app/action/SelectProtocol?sid=S000AWZ6&selectaction=Edit&uid=U0001PPF&ts=7&cx=-8jv7m2 ClinicalTrials.gov Identifier: NCT04999436. Registered 5 November 2021, https://register.

CLINICALTRIALS

gov/prs/app/action/SelectProtocol?sid=S000AYWW&selectaction=Edit&uid=U0001PPF&ts=11&cx=9tny7v.

Attitudes and beliefs regarding race-targeted genetic testing of Black people: A systematic review

Geographical ancestry has been associated with an increased risk of various genetic conditions. Race and ethnicity often have been used as proxies for geographical ancestry. Despite numerous problems associated with the crude reliance on race and ethnicity as proxies for geographical ancestry, some genetic testing in the clinical, research, and employment settings has been and continues to be race- or ethnicity-based. Race-based or race-targeted genetic testing refers to genetic testing offered only or primarily to people of particular racial or ethnic groups because of presumed differences among groups. One current example is APOL1 testing of Black kidney donors. Race-based genetic testing raises numerous ethical and policy questions. Given the ongoing reliance on the Black race in genetic testing, it is important to understand the views of people who identify as Black or are identified as Black (including African American, Afro-Caribbean, and Hispanic Black) regarding race-based genetic testing that targets Black people because of their race. We conducted a systematic review of studies and reports of stakeholder-engaged projects that examined how people who identify as or are identified as Black perceive genetic testing that specifically presumes genetic differences exist among racial groups or uses race as a surrogate for ancestral genetic variation and targets Black people. Our review identified 14 studies that explicitly studied this question and another 13 that implicitly or tacitly studied this matter. We found four main factors that contribute to a positive attitude toward race-targeted genetic testing (facilitators) and eight main factors that are associated with concerns regarding race-targeted genetic testing (barriers). This review fills an important gap. These findings should inform future genetic research and the policies and practices developed in clinical, research, public health, or other settings regarding genetic testing.

The key role of NLRP3 and STING in APOL1-associated podocytopathy

Coding variants in apolipoprotein L1 (APOL1), termed G1 and G2, can explain most excess kidney disease risk in African Americans; however, the molecular pathways of APOL1-induced kidney dysfunction remain poorly understood. Here, we report that expression of G2 APOL1 in the podocytes of Nphs1rtTA/TRE-G2APOL1 (G2APOL1) mice leads to early activation of the cytosolic nucleotide sensor, stimulator of interferon genes (STING), and the NLR family pyrin domain-containing 3 (NLRP3) inflammasome. STING and NLRP3 expression was increased in podocytes from patients with high-risk APOL1 genotypes, and expression of APOL1 correlated with caspase-1 and gasdermin D (GSDMD) levels. To demonstrate the role of NLRP3 and STING in APOL1-associated kidney disease, we generated transgenic mice with the G2 APOL1 risk variant and genetic deletion of Nlrp3 (G2APOL1/Nlrp3 KO), Gsdmd (G2APOL1/Gsdmd KO), and STING (G2APOL1/STING KO). Knockout mice displayed marked reduction in albuminuria, azotemia, and kidney fibrosis compared with G2APOL1 mice. To evaluate the therapeutic potential of targeting NLRP3, GSDMD, and STING, we treated mice with MCC950, disulfiram, and C176, potent and selective inhibitors of NLRP3, GSDMD, and STING, respectively. G2APOL1 mice treated with MCC950, disulfiram, and C176 showed lower albuminuria and improved kidney function even when inhibitor treatment was initiated after the development of albuminuria.

Opinions of African American adults about the use of apolipoprotein L1 (ApoL1) genetic testing in living kidney donation and transplantation

Apolipoprotein L1 (ApoL1) predictive genetic testing for kidney disease, and its emerging role in transplantation, remains controversial as it may exacerbate underlying disparities among African Americans (AAs) at increased risk. We conducted an online simulation among AAs (N = 585) about interest in ApoL1 testing and its cofactors, under 2 scenarios: as a potential living donor (PLD), and as a patient awaiting transplantation. Most respondents (61%) expressed high interest in genetic testing as a PLD: age ≥35 years (adjusted odds ratio [aOR], 1.75; 95% confidence interval [CI], 1.18, 2.60, P = .01), AA identity (aOR, 1.67; 95% CI, 1.02, 2.72, P = .04), perceived kidney disease risk following donation (aOR, 1.68; 95% CI, 1.03, 2.73, P = .03), interest in genetics (aOR, 2.89; 95% CI, 1.95, 4.29, P = .001), and genetics self-efficacy (aOR, 2.38; 95% CI, 1.54, 3.67, P = .001) were positively associated with ApoL1 test interest. If awaiting transplantation, most (89%) believed that ApoL1 testing should be done on AA deceased donors, and older age (aOR, 1.85; 95% CI, 1.03, 3.32, P = .04) and greater interest in genetics (aOR, 2.61; 95% CI, 1.41, 4.81, P = .002) were associated with interest in testing deceased donors. Findings highlight strong support for ApoL1 testing in AAs and the need to examine such opinions among PLDs and transplant patients to enhance patient education efforts.

Apolipoprotein L1: role in the evaluation of kidney transplant donors

PURPOSE OF REVIEW

To summarize the current state of evidence regarding the role of apolipoprotein L1 (APOL1) genotyping in evaluating donors for kidney transplantation.

RECENT FINDINGS

African ancestry is associated with an increased risk of kidney failure following living donation. Moreover, kidney transplants from African ancestry deceased donors have an increased risk of graft failure. Preliminary evidence suggests that APOL1 genotype may mediate at least a portion of this racial variation, with high-risk APOL1 genotypes defined by presence of two renal risk variants (RRVs). A pilot study 136 African ancestry living donors found that those with APOL1 high-risk genotypes had lower baseline kidney function and faster rates of kidney function decline after donation. To date, three retrospective studies identified a two-to-three times greater risk of allograft failure associated with kidneys from donors with high-risk APOL1 genotype. Active research initiatives seek to address unanswered questions, including reproducibility in large national samples, the role of 'second hits' injuries, and impact of recipient genotype, with a goal to build consensus on applications for policy and practice.

SUMMARY

As evidence evolves, APOL1 genotyping may have applications for organ quality scoring in deceased donor kidney allocation, and for the evaluation and selection of living donor candidates.

Ethical challenges in nephrology: a call for action

The American Society of Nephrology, the European Renal Association-European Dialysis and Transplant Association and the International Society of Nephrology Joint Working Group on Ethical Issues in Nephrology have identified ten broad areas of ethical concern as priority challenges that require collaborative action. Here, we describe these challenges - equity in access to kidney failure care, avoiding futile dialysis, reducing dialysis costs, shared decision-making in kidney failure care, living donor risk evaluation and decision-making, priority setting in kidney disease prevention and care, the ethical implications of genetic kidney diseases, responsible advocacy for kidney health and management of conflicts of interest - with the aim of highlighting the need for ethical analysis of specific issues, as well as for the development of tools and training to support clinicians who treat patients with kidney disease in practising ethically and contributing to ethical policy-making.

Practical Considerations for APOL1 Genotyping in the Living Kidney Donor Evaluation

BACKGROUND

Association between the apolipoprotein L1 gene (APOL1) and nephropathy has altered the epidemiology of chronic kidney disease. In addition, donor APOL1 genotypes play important roles in the time to allograft failure in kidneys transplanted from deceased donors and the safety of living kidney donation.

METHODS

This article reviews genetic testing for inherited kidney disease in living kidney donors to improve donor safety. APOL1 genotyping in donors with recent African ancestry is considered.

RESULTS

Based on current data, transplant physicians should discuss APOL1 genotyping with potential living kidney donors self-reporting recent African ancestry. Until results from APOL1 Long-term Kidney Transplant Outcomes Network ancillary studies are available, we present practical approaches from our experience for considering APOL1 genotyping in the living donor evaluation.

CONCLUSIONS

Transplant physicians should inform potential living kidney donors at risk for APOL1-associated nephropathy about the gene and possibility of genetic testing early in the donor evaluation, well before scheduling the donor nephrectomy. Transplant programs must weigh risks of performing a donor nephrectomy in those with 2 APOL1 renal risk variants (high-risk genotypes), particularly younger individuals. Our program counsels kidney donors with APOL1 high-risk genotypes in the same fashion as with risk genotypes in other nephropathy genes. Because most African American kidney donor candidates lacking hypertension, proteinuria and reduced kidney function after workup will not possess APOL1 high-risk genotypes, genetic testing is unlikely to markedly increase donor declines and may reassure donors with regard to their long-term kidney outcomes, potentially increasing the number of African American donors.

Variation of ApoL1 Testing Practices for Living Kidney Donors

INTRODUCTION

Tests exist for ApoL1 genetic variants to determine whether a potential donor's kidneys are at increased risk of kidney failure. Variants of the ApoL1 gene associated with increased risk are primarily found in people with West African ancestry. Given uncertainty about clinical implications of ApoL1 test results for living kidney donors and recipients and the lack of uniform guidelines for ApoL1 testing, transplant centers across the United States vary in ApoL1 testing practices.

RESEARCH QUESTIONS

(1) What approach do transplant centers take to determine whether prospective donors are of West African ancestry? (2)How do transplant centers engage potential donors during the ApoL1 testing process? (3) What do transplant centers identify as concerns and barriers to ApoL1 testing? and (4) What actions do transplant centers take when a potential donor has 2 ApoL1 risk variants?

DESIGN

We explored the current practices of transplant centers by surveying nephrologists and transplant surgeons at transplant centers evaluating the majority of black living donors in the United States.

RESULTS

About half of these transplant centers offered ApoL1 testing. Of those who offered ApoL1 testing, only half involved the donor in decision-making about donation when the donor has 2 risk variants.

DISCUSSION

Unaddressed differences in the priorities of transplant centers and black living donors may stigmatize black donors and undermine trust in the health-care and organ donation systems. Variation in transplant center testing practices points to the critical need for further research and community engagement to inform the development of guidelines for ApoL1 testing.

Donor-Recipient Relationship and Risk of ESKD in Live Kidney Donors of Varied Racial Groups

RATIONALE & OBJECTIVE

Risk factors for kidney failure are the basis of live kidney donor candidate evaluation. We quantified risk for end-stage kidney disease (ESKD) by the biological relationship of the donor to the recipient, a risk factor that is not addressed by current clinical practice guidelines.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

A cohort of 143,750 US kidney donors between 1987 and 2017.

EXPOSURE

Biological relationship of donor and recipient.

OUTCOME

ESKD. Donors' records were linked to national dialysis and transplantation registries to ascertain development of the outcome.

ANALYTIC APPROACH

Donors were observed over a median of 12 (interquartile range, 6-18; maximum, 30) years. Survival analysis methods that account for the competing risk for death were used.

RESULTS

Risk for ESKD varied by orders of magnitude across donor-recipient relationship categories. For Asian donors, risks compared with unrelated donors were 259.4-fold greater for identical twins (95% CI, 19.5-3445.6), 4.7-fold greater for full siblings (95% CI, 0.5-41.0), 3.5-fold greater for offspring (95% CI, 0.6-39.5), 1.0 for parents, and 1.0 for half-sibling or other biological relatives. For black donors, risks were 22.5-fold greater for identical twin donors (95% CI, 4.7-107.0), 4.1-fold for full siblings (95% CI, 2.1-7.8), 2.7-fold for offspring (95% CI, 1.4-5.4), 3.1-fold for parents (95% CI, 1.4-6.8), and 1.3-fold for half-sibling or other biological relatives (95% CI, 0.5-3.3). For white donors, risks were 3.5-fold greater for identical twin donors (95% CI, 0.5-25.3), 2.0-fold for full siblings (95% CI, 1.4-2.8), 1.4-fold for offspring (95% CI, 0.9-2.3), 2.9-fold for parents (95% CI, 2.0-4.1), and 0.8-fold for half-sibling or other biological relatives (95% CI, 0.3-1.6).

LIMITATIONS

Insufficient sample size in some race and relationship groups. Absence of data for family history of kidney disease for donors biologically unrelated to their recipients.

CONCLUSIONS

Marked differences in risk for ESKD across types of donor-recipient relationship were observed for Asian, black, and white donors. These findings warrant further validation with more robust data to better inform clinical practice guidelines.

APOL1 Genetic Testing in Living Kidney Transplant Donors

The presence of 2 apolipoprotein L1 gene (APOL1) risk variants is associated with increased risk for chronic kidney disease and end-stage kidney disease. Inferior allograft outcomes following transplantation with kidneys from donors with 2 risk variants have also been reported. These data, coupled with anecdotal case reports and a recent cohort study of living donors, raise important questions about the potential increased kidney disease risk for living donors with APOL1 risk variants and the need for testing as part of the standard living donor evaluation process. We identify a series of questions that are central to the development of clinical policy regarding APOL1 testing of potential living kidney donors given the current uncertainty over the clinical implications of having 2 risk variants. We explore the ethical challenges that arise when determining when and to whom APOL1 testing should be offered, what potential donors should be told about APOL1 testing, how test results should be used to determine suitability for donation, if and when recipients should have access to results, and how clinical policy regarding APOL1 testing should be established.

Apolipoprotein L1 Testing in African Americans: Involving the Community in Policy Discussions

BACKGROUND

Apolipoprotein A1 (APOL1) gene variants occurring in people of West African descent contribute to the greater burden of kidney disease among African Americans. These variants are associated with increased risk of nondiabetic nephropathy, more rapid progression of chronic kidney disease, and shorter survival of donor kidneys after transplantation. However, only a minority of people with APOL1-associated risk develops kidney disease and specific clinical measures to address APOL1-associated risk are lacking. Given these uncertainties, we sought to engage members of the African American public in discussions with other stakeholders about the appropriate use of APOL1 testing.

METHODS

Formative interviews with community members, researchers, and clinicians in Seattle WA, Nashville TN, and Jackson MS, provided baseline information about views toward APOL1 testing and informed the design of 3 community-based deliberations among African Americans. A national meeting held in March 2018 included 13 community members, 7 scientific advisors and 26 additional researchers, clinicians, bioethicists, patient advocates, and representatives from professional organizations and federal funding agencies. Using small break-out and plenary discussion, the group agreed on recommendations based on current knowledge about APOL1-associated risk.

RESULTS

Meeting outcomes included recommendations to develop educational materials about APOL1 for community members and clinicians; to offer APOL1 research results to participants; and on the use of APOL1testing in kidney transplant programs. The group recommended against the routine offer of APOL1 testing in clinical care. Areas of disagreement included whether kidney transplant programs should require APOL1 testing of prospective living donors or bar individuals with APOL1 risk from donating kidneys and whether testing should be available on request in routine clinical care.

CONCLUSION

We recommend continued discussion among stakeholders and concerted efforts to ensure active and informed participation of members of the affected community to guide research on APOL1 and kidney disease.

The true risk of living kidney donation

PURPOSE OF REVIEW

The safety of living donor nephrectomy is essential to the continued success, growth, and sustainability of the clinical practice of living donor kidney transplantation. This review summarizes recent advances in our understanding of the perioperative and long-term risks faced by living kidney donors.

RECENT FINDINGS

Although adverse perioperative complications are extremely rare, donors particularly men, Black, or obese, frequently experience minor complications that result in delayed return to normal duties at home and work. Similarly, although long-term complications such as end-stage renal disease (ESRD) are rare, recent studies suggest a relative increase in risk of ESRD that is attributable to donation. Several risk calculators have been developed to help donors and their care providers quantify the baseline and postdonation risk of ESRD based on demographic and health characteristics. Thresholds of risk may help define what is an acceptable level of risk to the donor and the transplant center.

SUMMARY

Individualized risk calculators now allow care providers and potential donors to objectively and transparently participate in shared decision-making about the safety of living kidney donation.

Hyperfiltration-mediated Injury in the Remaining Kidney of a Transplant Donor

Kidney donors face a small but definite risk of end-stage renal disease 15 to 30 years postdonation. The development of proteinuria, hypertension with gradual decrease in kidney function in the donor after surgical resection of 1 kidney, has been attributed to hyperfiltration. Genetic variations, physiological adaptations, and comorbidities exacerbate the hyperfiltration-induced loss of kidney function in the years after donation. A focus on glomerular hemodynamics and capillary pressure has led to the development of drugs that target the renin-angiotensin-aldosterone system (RAAS), but these agents yield mixed results in transplant recipients and donors. Recent work on glomerular biomechanical forces highlights the differential effects of tensile stress and fluid flow shear stress (FFSS) from hyperfiltration. Capillary wall stretch due to glomerular capillary pressure increases tensile stress on podocyte foot processes that cover the capillary. In parallel, increased flow of the ultrafiltrate due to single-nephron glomerular filtration rate elevates FFSS on the podocyte cell body. Although tensile stress invokes the RAAS, FFSS predominantly activates the cyclooxygenase 2-prostaglandin E2-EP2 receptor axis. Distinguishing these 2 mechanisms is critical, as current therapeutic approaches focus on the RAAS system. A better understanding of the biomechanical forces can lead to novel therapeutic agents to target FFSS through the cyclooxygenase 2-prostaglandin E2-EP2 receptor axis in hyperfiltration-mediated injury. We present an overview of several aspects of the risk to transplant donors and discuss the relevance of FFSS in podocyte injury, loss of glomerular barrier function leading to albuminuria and gradual loss of renal function, and potential therapeutic strategies to mitigate hyperfiltration-mediated injury to the remaining kidney.

A National Survey of Transplant Surgeons and Nephrologists on Implementing Apolipoprotein L1 (APOL1) Genetic Testing Into Clinical Practice

Introduction:

There is debate over whether Apolipoprotein L1 (APOL1) gene risk variants contribute to African American (AA) live donors’ (LD) increased risk of kidney failure. Little is known about factors influencing physicians’ integration of APOL1 genetic testing of AA LDs into donor evaluation.

Design:

We conducted a cross-sectional survey, informed by Roger’s Diffusion of Innovations theory, among nephrology and surgeon members of the American Society of Nephrology, American Society of Transplantation, and American Society of Transplant Surgeons about their practices of and attitudes about APOL1 genetic testing of AA potential LDs. Descriptive statistics and bivariate analyses were performed.

Results:

Of 383 completed surveys, most physicians believed that APOL1 testing can help AA LDs make more informed donation decisions (87%), and the addition of APOL1 testing offers better clinical information about AA LD’s eligibility for donation than existing evaluation approaches (74%). Among respondents who evaluate LDs (n = 345), 63% would definitely or probably begin or continue using APOL1 testing in the next year, however, few use APOL1 testing routinely (4%) or on a case-by-case basis (14%). Most did not know the right clinical scenario to order APOL1 testing (59%), but would use educational materials to counsel AA LDs about APOL1 testing (97%).

Discussion:

Although physicians were highly supportive of APOL1 genetic testing for AA LDs, few physicians use APOL1 testing. As more physicians intend to use APOL1 testing, an ethical framework and clinical decision support are needed presently to assist clinicians in clarifying the proper indication of APOL1 genetic testing.

Developing an ethics framework for living donor transplantation

Both living donor transplantation and human subjects research expose one set of individuals to clinical risks for the clinical benefits of others. In the Belmont Report, the National Commission for the Protection of Human Subjects of Biomedical and Behavior Research (National Commission) articulated three principles to serve as the basis for a research ethics framework: respect for persons, beneficence and justice. In contrast, living donor transplantation lacks a framework. In this manuscript, we adapt the three principles articulated in the Belmont Report to serve as the foundation for an ethics framework for living donor transplantation which we supplement with the principles of vulnerability and responsibility. The National Commission supported additional protections for vulnerable groups of potential research participants. In 2001, Kenneth Kipnis effectively argued that the concept of vulnerable groups failed to explore in what ways particular groups of people were vulnerable, thereby risking unnecessary protections for some and inadequate protections for others. He proposed a taxonomy that explored different types of vulnerabilities that all research participants may experience to provide a more robust framework for human subjects protections, which we adapt to living donors. Robert Goodin claims that health professionals, who stand in special relationship with patients, are responsible for promoting and protecting their well-being. In living donor transplantation, the donor transplant team is responsible for empowering prospective donors to address their vulnerabilities and/or for protecting those who cannot by disqualifying them from donation.

African American Living Donors' Attitudes About APOL1 Genetic Testing: A Mixed Methods Study

RATIONALE & OBJECTIVE

African American live kidney donors ("donors") have a greater risk for kidney failure than European American donors. Apolipoprotein L1 gene (APOL1) variants in African Americans may be associated with this disparity.

STUDY DESIGN

Cross-sectional mixed-methods design.

SETTING & PARTICIPANTS

African American donors at 1 transplantation center.

ANALYTICAL APPROACH

Semistructured interviews assessed attitudes about APOL1 genetic testing, willingness to undergo APOL1 testing, hypothetical decisions about donating with 2 APOL1 variants, and demographics. Surveys assessed perceptions of ethnic identity and genetics knowledge. Interview transcriptions were analyzed using thematic analysis. Survey data were analyzed using descriptive statistics.

RESULTS

23 donors participated in semistructured interviews. Most (96%) reported that transplantation centers should routinely offer APOL1 genetic testing to all African American potential donors. Most (87%) would have been willing to undergo APOL1 testing before donating. Although study participants noted that APOL1 testing may deter African American potential donors from donating, most (61%) would have donated even if they had 2 high-risk APOL1 variants. Several themes emerged. Study participants believed that APOL1 testing was beneficial for providing information to help donors make informed donation decisions. Participants expressed concern about APOL1 variants placing donors at harm for kidney failure, and therefore valued taking preventive health measures. Participants believed that potential donors would experience psychological distress from learning that they have 2 gene variants and could harm their recipients. Participants were apprehensive about insurance coverage and costs of APOL1 testing and feared that APOL1 genetic test results could discriminate against African Americans.

LIMITATIONS

Findings may not be generalizable to African American potential donors.

CONCLUSIONS

Findings suggest that African American donors support APOL1 genetic testing yet fear that APOL1 variants and genetic testing could adversely affect donors' health and ethnic identity. Transplantation centers using APOL1 genetic testing should address African American donors' concerns about APOL1 genetic testing to optimize future donors' informed consent practices.

Impact of the individualized risks of end-stage renal disease on living kidney donor selection

Background

It is recommended to determine the risks of end-stage renal disease (ESRD) in living donor candidates. The aim of this study was to determine how many candidates would have been cleared for donation according to different thresholds of risks.

Methods

Four pre-donation and post-donation risks of ESRD were calculated retrospectively using online tools (http://www.transplantmodels.com/) and the calculator of the University of Minnesota for 151 living kidney donors and 27 patients disqualified for living donation based on a glomerular filtration rate (GFR) <80 mL/min/1.73 m2.

Results

A complete overlap of the pre-donation 15-year ESRD risk, pre-donation projected lifetime ESRD risk, post-donation 15-year ESRD risk and the Minnesota post-donation 15-year risk of ESRD or GFR <30 mL/min/1.73 m2 was observed for the living kidney donors and the disqualified candidates. We next defined different thresholds of pre- and post-donation risks of ESRD that could be used for clearing living donation. In candidates over 61 years of age, the use of a pre-donation 15-year ESRD risk of 0.25% and/or a post-donation 15-year ESRD risk of 50 per 10 000 would increase the percentage of donors by 28.6% and 26.3%, respectively. Conversely, only 22.3% of donors aged 18-35 years would have been selected by using a pre-donation projected lifetime ESRD risk <0.5%.

Conclusions

The use of these ESRD risks would significantly modify donor selection by increasing the percentage of donors ≥61 years of age with GFR <80 mL/min/1.73 m2 and by decreasing the percentage of donors aged 18-35 years with a high GFR.

Xenotransplantation

The transplantation of living cells, tissues or organs from one species to another is termed xenotransplantation. The history of xenotransplantation is as old as allogeneic transplantation itself. Early attempts were made at a time when the immunologic basis of organ rejection were poorly understood. The advent of potent immunosuppressive medications along with the parallel advances in the field of genetic engineering has provided a fresh perspective on the role of xenotransplantation as a means to alleviate the disparity between the number of candidates on the waitlist and the available organs. As the science behind xenotransplantation advances, the transplantation community must take it upon themselves to educate the community at large regarding both the benefits and potential risks of this promising field.

APOL1 Nephropathy: A Population Genetics and Evolutionary Medicine Detective Story

Common DNA sequence variants rarely have a high-risk association with a common disease. When such associations do occur, evolutionary forces must be sought, such as in the association of apolipoprotein L1 (APOL1) gene risk variants with nondiabetic kidney diseases in populations of African ancestry. The variants originated in West Africa and provided pathogenic resistance in the heterozygous state that led to high allele frequencies owing to an adaptive evolutionary selective sweep. However, the homozygous state is disadvantageous and is associated with a markedly increased risk of a spectrum of kidney diseases encompassing hypertension-attributed kidney disease, focal segmental glomerulosclerosis, human immunodeficiency virus nephropathy, sickle cell nephropathy, and progressive lupus nephritis. This scientific success story emerged with the help of the tools developed over the past 2 decades in human genome sequencing and population genomic databases. In this introductory article to a timely issue dedicated to illuminating progress in this area, we describe this unique population genetics and evolutionary medicine detective story. We emphasize the paradox of the inheritance mode, the missing heritability, and unresolved associations, including cardiovascular risk and diabetic nephropathy. We also highlight how genetic epidemiology elucidates mechanisms and how the principles of evolution can be used to unravel conserved pathways affected by APOL1 that may lead to novel therapies. The APOL1 gene provides a compelling example of a common variant association with common forms of nondiabetic kidney disease occurring in a continental population isolate with subsequent global admixture. Scientific collaboration using multiple experimental model systems and approaches should further clarify pathomechanisms further, leading to novel therapies.

Clinical Genetic Testing for APOL1: Are we There Yet?

End-stage renal disease (ESRD) disproportionately affects African Americans, who are two to four times more likely than European Americans to develop ESRD. Two independent variants of the apolipoprotein L1 (APOL1) gene, G1 and G2, have been associated with a 7- to 10-fold greater risk of developing nondiabetic ESRD in African Americans. Those who inherit two risk variants (G1/G1, G2/G2, or G1/G2) are also more likely to develop ESRD at a younger age and to have progression of chronic kidney disease. Currently, it is not known what proportion of persons with high-risk genotypes will develop ESRD in the general population, the exact mechanism of injury for APOL1-related risk, its relation to environmental exposures, or whether patients with comorbid conditions are more likely to develop ESRD. To address the above uncertainties, research that includes assessment of APOL1 status is needed before guidelines for general testing can be endorsed. Currently, APOL1 testing has been proposed as part of kidney transplant protocols both for living donors and recipients. However, because of uncertainties regarding the clinical implications of APOL1 variants, testing could generate confusion, anxiety, or stigma. Multiple forms of evidence, including the views of community members, are needed to support responsible approaches to providing information about APOL1 status as part of clinical care or in population screening. Informed consent with subsequent counseling regarding the risks and benefits of APOL1 testing should be considered for patients at high risk.

APOL1: The Balance Imposed by Infection, Selection, and Kidney Disease

Chronic kidney disease (CKD) affects millions of people and constitutes a major health and financial burden worldwide. People of African descent are at an increased risk of developing kidney disease, which is mostly explained by two variants in the Apolipoprotein L1 (APOL1) gene that are found only in people of west African origin. It is hypothesized that these variants were genetically selected due to the protection they afford against African sleeping sickness, caused by the parasite Trypanosoma brucei. Targeting mutant APOL1 could have substantial therapeutic potential for treating kidney disease. In this review, we will describe the intriguing interplay between microbiology, genetics, and kidney disease as revealed in APOL1-associated kidney disease, discuss APOL1-induced cytotoxicity and its therapeutic implications.

Apolipoprotein L1 and Chronic Kidney Disease Risk in Young Potential Living Kidney Donors

OBJECTIVE

The aim of this study was to develop a novel chronic kidney disease (CKD) risk prediction tool for young potential living kidney donors.

SUMMARY OF BACKGROUND DATA

Living kidney donor selection practices have evolved from examining individual risk factors to a risk calculator incorporating multiple characteristics. Owing to limited long-term data and lack of genetic information, current risk tools lack precision among young potential living kidney donors, particularly African Americans (AAs).

METHODS

We identified a cohort of young adults (18-30 years) with no absolute contraindication to kidney donation from the longitudinal cohort study Coronary Artery Risk Development in Young Adults. Risk associations for CKD (estimated glomerular filtration rate <60 mL/min/1.73 m) were identified and assigned weighted points to calculate risk scores.

RESULTS

A total of 3438 healthy adults were identified [mean age 24.8 years; 48.3% AA; median follow-up 24.9 years (interquartile range: 24.5-25.2)]. For 18-year olds, 25-year projected CKD risk varied by ethnicity and sex even without baseline clinical and genetic abnormalities; risk was 0.30% for European American (EA) women, 0.52% for EA men, 0.52% for AA women, 0.90% for AA men. Among 18-year-old AAs with apolipoprotein L1 gene (APOL1) renal-risk variants without baseline abnormalities, 25-year risk significantly increased: 1.46% for women and 2.53% for men; among those with 2 APOL1 renal-risk variants and baseline abnormalities, 25-year risk was higher: 2.53% to 6.23% for women and 4.35% to 10.58% for men.

CONCLUSIONS

Young AAs were at highest risk for CKD, and APOL1 renal-risk variants drove some of this risk. Understanding the genetic profile of young AA potential living kidney donors in the context of baseline health characteristics may help to inform candidate selection and counseling.

Risk of ESRD in prior living kidney donors

We studied End-Stage Renal Disease (ESRD) in living kidney donors (LKDs) who donated in the United States between 1994 and 2016 (n = 123 526), using Organ Procurement and Transplantation Network and Centers for Medicare and Medicaid Services data. Two hundred eighteen LKDs developed ESRD, with a median of 11.1 years between donation and ESRD. Absolute 20-year risk was low but not uniform, with risk associated with race, age, and sex and increasing exponentially over time. LKDs had increased risk of ESRD if they were male (adjusted hazard ratio [aHR]: 1.75, 95% confidence interval [95%CI]: 1.33-2.31), had higher BMI (aHR: 1.34 per 5 kg/m² , 95%CI: 1.10-1.64) or lower estimated GFR (aHR: 0.89 per 10 mL/min, 95% CI: 0.80-0.99), were first-degree relatives of the recipient (parent: [aHR: 2.01, 95% CI: 1.26-3.21]; full sibling [aHR: 1.87, 95%CI: 1.23-2.84]; identical twin [aHR: 19.79, 95%CI: 7.65-51.24]), or lived in lower socioeconomic status neighborhoods at donation (aHR: 0.87 per $10k increase; 95%CI: 0.77-0.99). We found a significant interaction between donation age and race, with higher risk at older ages for white LKDs (aHR: 1.26 per decade, 95%CI: 1.04-1.54), but higher risk at younger ages for black LKDs (aHR: 0.75 per decade, 95%CI: 0.57-0.99). These findings further inform risk assessment of potential LKDs.

Simultaneous Pancreas and Kidney Transplantation is Associated With Inferior Long-Term Outcomes in African Americans

OBJECTIVES

Simultaneous pancreas and kidney transplant (SPK) is the most effective treatment for patients with type 1 diabetes mellitus and renal failure. However, the effect of ethnicity on SPK outcomes is not well understood.

METHODS

We studied the influence of recipient ethnicity on SPK using the United Network for Organ Sharing database. A retrospective review of 20,196 SPK patients from 1989 to 2014 was performed. The recipients were divided into 4 groups: 15,833 whites (78.40%), 2708 African Americans (AA) (14.39%), 1456 Hispanics (7.21%), and 199 Asians (0.99%).

RESULTS

Hispanics and Asians experienced the best overall graft and patient outcomes. Both groups demonstrated significantly superior graft and patient survival rates compared with whites at 1, 3, 5, 10, and 15 years (all P < 0.0001). African Americans experienced significantly superior 1- and 3-year patient survival compared with whites (both P < 0.0001). African Americans also experienced significantly superior 1-year kidney and pancreas graft survival compared with whites (P < 0.0001). However, AA experienced significantly inferior patient and allograft outcomes for all other time points compared with whites.

CONCLUSIONS

Based on United Network for Organ Sharing data from 1989 to 2014, AA have worse long-term patient and graft survival rates compared with whites, Hispanics, and Asians undergoing SPK.

Alemtuzumab Induction Is Associated With an Equalization of Outcomes Between White and African American Kidney Transplant Recipients

OBJECTIVES

Our aim was to assess outcomes in White and African American kidney transplant recipients after induction with alemtuzumab.

MATERIALS AND METHODS

We performed a retrospective study of 464 patients who received deceased-donor kidney transplants and were induced with alem-tuzumab between March 2006 and May 2015. We evaluated ethnic influences on patient and graft survival, delayed graft function, allograft failure, and rejection.

RESULTS

There were 337 White (67.3%) and 127 African American (25.3%) patients. We observed no significant differences in 1-, 3-, 5-, and 7- year death-censored graft survival. We also observed no significant differences in 1-, 3-, and 5-year patient survival rates. Having African American ethnicity was not a significant predictor of rejection, graft survival, or patient survival.

CONCLUSIONS

Our results indicate that recipient ethnicity is not a predictor of rejection, graft survival, or patient survival. White and African American kidney transplant recipients induced with alemtuzumab experienced an equalization of outcomes.

Health Disparities in Kidney Transplantation for African Americans

BACKGROUND

The persistent challenges of bridging healthcare disparities for African Americans (AAs) in need of kidney transplantation continue to be unresolved at the national level. This healthcare disparity is multifactorial: stemming from limited kidney donors suitable for AAs; inconsistent care coordination and suboptimal risk factor control; social determinants, low socioeconomic status, reduced access to care; and mistrust of clinicians and the healthcare system.

SUMMARY

There are numerous opportunities to significantly lessen the disparities in kidney transplantation for AAs through the following measures: the adoption of new care and patient engagement models that include education, enhanced practice-level cultural sensitivity, and timely referral as well as increased research on the impact of the environment on genetic risk, and implementation of new transplantation-related policies. Key Messages: This systematic review describes pretransplant concerns related to access to kidney transplantation, posttransplant complications, and policy interventions to address the challenging issues associated with kidney transplantation in AAs.

KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors

The 2017 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors is intended to assist medical professionals who evaluate living kidney donor candidates and provide care before, during and after donation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach and guideline recommendations are based on systematic reviews of relevant studies that included critical appraisal of the quality of the evidence and the strength of recommendations. However, many recommendations, for which there was no evidence or no systematic search for evidence was undertaken by the Evidence Review Team, were issued as ungraded expert opinion recommendations. The guideline work group concluded that a comprehensive approach to risk assessment should replace decisions based on assessments of single risk factors in isolation. Original data analyses were undertaken to produce a "proof-in-concept" risk-prediction model for kidney failure to support a framework for quantitative risk assessment in the donor candidate evaluation and defensible shared decision making. This framework is grounded in the simultaneous consideration of each candidate's profile of demographic and health characteristics. The processes and framework for the donor candidate evaluation are presented, along with recommendations for optimal care before, during, and after donation. Limitations of the evidence are discussed, especially regarding the lack of definitive prospective studies and clinical outcome trials. Suggestions for future research, including the need for continued refinement of long-term risk prediction and novel approaches to estimating donation-attributable risks, are also provided.In citing this document, the following format should be used: Kidney Disease: Improving Global Outcomes (KDIGO) Living Kidney Donor Work Group. KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors. Transplantation. 2017;101(Suppl 8S):S1-S109.

Integrating APOL1 Gene Variants Into Renal Transplantation: Considerations Arising From the American Society of Transplantation Expert Conference

Thirteen percent of individuals of African ancestry express two variant copies of the gene encoding apolipoprotein 1 (APOL1) that has been associated with an increased risk of end-stage renal disease (ESRD) in the general population. Limited studies suggest that the survival of transplanted kidneys from donors expressing two APOL1 risk alleles is inferior to that of kidneys from donors with zero or one risk allele. In living kidney donation, two case reports describe donors expressing two APOL1 risk alleles who developed ESRD. Given the potential impact of APOL1 variants on the utility and safety of kidney transplantation and living kidney donation, the American Society of Transplantation convened a meeting with the goals of summarizing the current state of knowledge with respect to transplantation and APOL1, identifying knowledge gaps and studies to address these gaps, and considering approaches to integrating APOL1 into clinical practice. The authors recognize that current data are not sufficient to support traditional evidence-based guidelines but also recognize that it may require several years to generate the necessary data. Thus, approaches as to how APOL1 might currently be integrated into the clinical decision-making process were considered. This report summarizes the group's deliberations.

Screening of Living Kidney Donors for Genetic Diseases Using a Comprehensive Genetic Testing Strategy

Related living kidney donors (LKDs) are at higher risk of end-stage renal disease (ESRD) compared with unrelated LKDs. A genetic panel was developed to screen 115 genes associated with renal diseases. We used this panel to screen six negative controls, four transplant candidates with presumed genetic renal disease and six related LKDs. After removing common variants, pathogenicity was predicted using six algorithms to score genetic variants based on conservation and function. All variants were evaluated in the context of patient phenotype and clinical data. We identified causal variants in three of the four transplant candidates. Two patients with a family history of autosomal dominant polycystic kidney disease segregated variants in PKD1. These findings excluded genetic risk in three of four relatives accepted as potential LKDs. A third patient with an atypical history for Alport syndrome had a splice site mutation in COL4A5. This pathogenic variant was excluded in a sibling accepted as an LKD. In another patient with a strong family history of ESRD, a negative genetic screen combined with negative comparative genomic hybridization in the recipient facilitated counseling of the related donor. This genetic renal disease panel will allow rapid, efficient and cost-effective evaluation of related LKDs.

Apolipoprotein L1 and apolipoprotein A-IV and their association with kidney function

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is a common disease with an estimated prevalence of 10-12%. There are pronounced differences between ethnicities with a 3-fold to 4-fold higher lifetime risk for end-stage kidney disease in African Americans compared to European Americans. The purpose of this review was to discuss recent findings on two apolipoproteins (apolipoprotein L1 and A-IV) in the context of kidney disease and kidney function.

RECENT FINDINGS

The observation that certain apolipoprotein L1 risk genotypes that are only present in African Americans might explain a major fraction of the ethnic differences for nondiabetic CKD has set the stage for this otherwise under-researched apolipoprotein. These risk genotypes on the one hand protect African Americans against African sleeping sickness but cause on the other hand several types of nondiabetic CKD. We are currently beginning to understand the mechanisms how apolipoprotein L1 is involved in the modification of lysosomal and cytoplasmic membranes. The second protein, apolipoprotein A-IV (apoA-IV), turned out to be an early marker of kidney impairment not only in patients with primary CKD but also in individuals from the general population. Genetic studies provided strong support of a causal effect of kidney function on apoA-IV concentrations.

SUMMARY

These two apolipoproteins have very distinct properties. Apolipoprotein L1 is causally involved in the development of nondiabetic CKD in African Americans. In contrast, apoA-IV is an early marker for kidney impairment.

Understanding and Communicating Medical Risks for Living Kidney Donors: A Matter of Perspective

Communicating the current knowledge of medical outcomes after live kidney donation necessary to support donor candidates in well informed decision-making requires grounding in perspectives of comparison. Baseline risk (without donating), risk attributable to donation, and absolute risk (after donating) need to be considered. Severe perioperative complications and death are rare, but vary by demographic, clinical, and procedure factors. Innovative capture of "healthy" controls designed to simulate donor selection processes has identified higher risk of ESRD attributable to donation in two studies; importantly, however, the absolute 15-year ESRD incidence in donors remains very low (0.3%). In the first decade after donation, the risk of all-cause mortality and cardiovascular events is no higher than in healthy nondonors. Pregnancies in donors may incur attributable risk of gestational hypertension or preeclampsia (11% versus 5% incidence in one study). A modest rise in uric acid levels beginning early after donation, and a small (1.4%) increase in the 8-year incidence of gout, have also been reported in comparisons to healthy nondonors. As in the general population, postdonation outcomes vary by race, sex, and age. Efforts to improve the counseling and selection of living donors should focus on developing tools for tailored risk prediction according to donor characteristics, and ideally, compared with similar healthy nondonors.

APOL1-Associated End-Stage Renal Disease in a Living Kidney Transplant Donor

Homozygosity for apolipoprotein-L1 (APOL1) risk variants has emerged as an important predictor of renal disease in individuals of African descent over the past several years. Additionally, these risk variants may be important predictors of renal allograft failure when present in a living or deceased donor. Currently, there is no universal recommendation for screening of potential donors. We present a case of end-stage renal disease with focal segmental glomerulosclerosis in a living donor 7 years following donor nephrectomy. Genetic assessment revealed homozygosity for the G1 high-risk APOL1 variant.

Introducing Genetic Tests With Uncertain Implications in Living Donor Kidney Transplantation

Genetic mutations in apolipoprotein L1 (ApoL1) are associated with kidney disease. Apolipoprotein L1 mutations are common in African Americans (∼39% and 12% have 1 and 2 high-risk alleles, respectively). Carrying 2 ApoL1 risk alleles may explain much of the excess rate of kidney failure in African Americans compared to European Americans. Apolipoprotein L1 also has implications for kidney transplantation. Kidney grafts from deceased donors with 2 ApoL1 risk alleles have worse graft survival, but outcomes appear unaffected by recipient ApoL1 status. Unknown is whether donation increases the risk of kidney failure in living donors with 2 ApoL1 risk alleles and whether their donated kidneys have worse graft survival. There are 4 options to consider: (1) remain silent about ApoL1 risk alleles and renal failure and wait for more data; (2) counsel about race, ApoL1, and subsequent renal failure abstractly but remain agnostic about donor testing until more data are available; (3) provide counseling and encourage genotyping of prospective living donors of African ancestry as part of the living donor workup; or (4) mandate testing of all prospective living donors. We support option 3, and recommend, with donor permission, to discuss the results with potential recipients to promote informed decision-making. We also argue for a voluntary donor registry that collects long-term follow-up information. We provide ethical arguments to support these recommendations.

Genomics in CKD: Is This the Path Forward?

Recent advances in genomics and sequencing technology have led to a better understanding of genetic risk in CKD. Genetics could account in part for racial differences in treatment response for medications including antihypertensives and immunosuppressive medications due to its correlation with ancestry. However, there is still a substantial lag between generation of this knowledge and its adoption in routine clinical care. This review summarizes the recent advances in genomics and CKD, discusses potential reasons for its underutilization, and highlights potential avenues for application of genomic information to improve clinical care and outcomes in this particularly vulnerable population.