APOL1 Risk Genotypes Are Associated With Early Kidney Damage in Children in Sub-Saharan Africa

APOL1 Nephropathy Risk Variants Through the Life Course: A Review

Two variant alleles of the gene apolipoprotein L1 (APOL1), known as risk variants (RVs), are a major contributor to kidney disease burden in those of African descent. The APOL1 protein contributes to innate immunity and may protect against Trypanosoma, HIV, Salmonella, and leishmaniasis. However, the effects of carrying 1 or more RVs contribute to a variety of disease processes starting as early as in utero and can be exacerbated by other factors (or "second hits"). Indeed, these genetic variations interact with environmental exposures, infections, and systemic disease to modify health outcomes across the life span. This review focuses on APOL1-associated diseases through the life-course perspective and discusses how early exposure to second hits can impact long-term outcomes. APOL1-related kidney disease typically presents in adolescents to young adults, and individuals harboring RVs are more likely to progress to kidney failure than are those with kidney disease who lack APOL-1 RVs. Ongoing research is aimed at elucidating the association of APOL1 RV effects with adverse donor and recipient kidney transplant outcomes. Unfortunately, there is currently no established treatment for APOL1-associated nephropathy. Long-term research is needed to evaluate the risk and protective factors associated with APOL1 RVs at different stages of life.

The changing landscape of HIV-associated kidney disease

The HIV epidemic has devastated millions of people globally, with approximately 40 million deaths since its start. The availability of antiretroviral therapy (ART) has transformed the prognosis of millions of individuals infected with HIV such that a diagnosis of HIV infection no longer automatically confers death. However, morbidity and mortality remain substantial among people living with HIV. HIV can directly infect the kidney to cause HIV-associated nephropathy (HIVAN) - a disease characterized by podocyte and tubular damage and associated with an increased risk of kidney failure. The reports of HIVAN occurring primarily in those of African ancestry led to the discovery of its association with APOL1 risk alleles. The advent of ART has led to a substantial decrease in the prevalence of HIVAN; however, reports have emerged of an increase in the prevalence of other kidney pathology, such as focal segmental glomerulosclerosis and pathological conditions associated with co-morbidities of ageing, such as hypertension and diabetes mellitus. Early initiation of ART also results in a longer cumulative exposure to medications, increasing the likelihood of nephrotoxicity. A substantial body of literature supports the use of kidney transplantation in people living with HIV, demonstrating significant survival benefits compared with that of people undergoing chronic dialysis, and similar long-term allograft and patient survival compared with that of HIV-negative kidney transplant recipients.

HIV-associated nephropathy in children: challenges in a resource-limited setting

HIV infection remains one of the leading causes of morbidity and mortality worldwide, especially in children living in resource-limited settings. Although the World Health Organization (WHO) recently recommended antiretroviral therapy (ART) initiation upon diagnosis regardless of the number of CD4, ART access remains limited, especially in children living in sub-Saharan Africa (SSA). HIV-infected children who do not receive appropriate ART are at increased risk of developing HIV-associated nephropathy (HIVAN). Although due to genetic susceptibility, SSA is recognized to be the epicenter of HIVAN, limited information is available regarding the burden of HIVAN in children living in Africa. The present review discusses the information available to date on the prevalence, pathogenesis, risk factors, diagnosis, and management of HIVAN in children, focusing on related challenges in a resource-limited setting.

Glomerular hyperfiltration: part 2-clinical significance in children

Glomerular hyperfiltration (GHF) is a phenomenon that can occur in various clinical conditions affecting the kidneys such as sickle cell disease, diabetes mellitus, autosomal dominant polycystic kidney disease, and solitary functioning kidney. Yet, the pathophysiological mechanisms vary from one disease to another and are not well understood. More so, it has been demonstrated that GHF may occur at the single-nephron in some clinical conditions while in others at the whole-kidney level. In this review, we explore the pathophysiological mechanisms of GHF in relation to various clinical conditions in the pediatric population. In addition, we discuss the role and mechanism of action of important factors such as gender, low birth weight, and race in the pathogenesis of GHF. Finally, in this current review, we further highlight the consequences of GHF in the progression of kidney disease.

Apolipoprotein L1 gene variants and kidney disease in patients with HIV: a systematic review and meta-analysis

BACKGROUND

The risk of various types of kidney disease is significantly increased in the presence of APOL1 high-risk genotype (carriage of two risk alleles), particularly HIV-associated nephropathy (HIVAN). However, there are discrepancies in the existing evidence about the level of association between APOL1 high-risk genotype and the risk of kidney diseases in people living with HIV (PLWHIV).

METHODS

This systematic review and meta-analysis was conducted to assess the relationship between the APOL1 genotypes and kidney disease in the HIV population. An a priori protocol registered on PROSPERO (ID: CRD42021253877), was followed by a systematic search of five electronic databases. Database-specific search terms were used to identify observational studies that evaluated the outcomes chosen in the review, based on a set of prespecified eligibility criteria. Using a random effect model, the odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were pooled for the meta-analysis.

RESULTS

After screening 4418 citations, 14 articles comprising 11,069 participants were included in this review. The risk of chronic kidney disease (CKD) in the HIV positive population was significantly increased in the presence of two APOL1 risk alleles (OR 4.65 [95% CI 3.51-6.15]). Also, a significant association was observed between the carriage of two risk APOL1 variants and proteinuria (OR 2.58 [95% CI 2.05-3.25]), HIVAN (OR 16.67 [95% CI 10.22-27.19]), and progression to end-stage kidney disease (ESKD) hazard ratio: 1.79 (95% CI 1.20-2.66).

CONCLUSION

This review highlights a strong association between the presence of two risk APOL1 variants and an increased risk of kidney disease in PLWHIV, and provides a more precise estimate of the effect size, with smaller 95% CIs for CKD, HIVAN, and progression to ESKD.

High risk APOL1 genotypes and kidney disease among treatment naïve HIV patients at Kano, Nigeria

Introduction

Racial disparities are known in the occurrence of kidney disease with excess risks found among people of African descent. Apolipoprotein L1 (APOL1) gene variants G1 and G2 are associated with kidney disease among HIV infected individuals of African descent in the USA as well as among black population in South Africa. We set out to investigate the prevalence of these high-risk variants and their effects on kidney disease among HIV infected patients in Northern Nigeria with hitherto limited information despite earlier reports of high population frequencies of these alleles from the Southern part of the country.

Methods

DNA samples obtained from the whole blood of 142 participants were genotyped for APOL1 G1 and G2 variants after initial baseline investigations including assessment of kidney function. Participants comprised 50 HIV positive patients with no evidence of kidney disease, 52 HIV negative individuals with no kidney disease and 40 HIV positive patients with chronic kidney disease (CKD) evidenced by persistent proteinuria and/or reduced eGFR, who also had a kidney biopsy. All the HIV positive patients were newly diagnosed and treatment naïve.

Results

The distribution of the APOL1 genotypes among the study participants revealed that 24.6% had a G1 risk allele and 19.0% a G2. The frequency of the High Risk Genotype (HRG) was 12.5% among those with CKD compared to 5.8% in the HIV negative group and zero in the HIV positive no CKD group. Having the HRG was associated with a higher odds for developing HIV Associated Nephropathy (HIVAN) (2 vs 0 risk alleles: OR 10.83, 95% CI 1.38–84.52; P = 0.023; 2 vs 0 or 1 risk alleles: OR 5.5, 95% CI 0.83–36.29; P = 0.07). The HRG was also associated with higher odds for Focal Segmental Glomerulosclerosis (FSGS) (2 vs 0 risk alleles: OR 13.0, 95% CI 2.06–81.91; P = 0.006 and 2 vs 0 or 1 risk alleles: OR 9.0, 95%CI 1.62–50.12; P = 0.01) when compared to the control group.

Conclusion

This study showed a high population frequency of the individual risk alleles of the APOL1 gene with higher frequencies noted among HIV positive patients with kidney disease. There is high association with the presence of kidney disease and especially FSGS and HIVAN among treatment naive HIV patients carrying two copies of the HRG.

Associations between APOL1 genetic variants and blood pressure in African American mothers and children from a U.S. pregnancy cohort: Modification by air pollution exposures

INTRODUCTION

Carriage of high-risk APOL1 genetic variants is associated with increased risks for kidney diseases in people of African descent. Less is known about the variants' associations with blood pressure or potential moderators.

METHODS

We investigated these associations in a pregnancy cohort of 556 women and 493 children identified as African American. Participants with two APOL1 risk alleles were defined as having the high-risk genotype. Blood pressure in both populations was measured at the child's 4-6 years visit. We fit multivariate linear and Poisson regressions and further adjusted for population stratification to estimate the APOL1-blood pressure associations. We also examined the associations modified by air pollution exposures (particulate matter ≤2.5 μ m in aerodynamic diameter [PM2.5] and nitrogen dioxide) and explored other moderators such as health conditions and behaviors.

RESULTS

Neither APOL1 risk alleles nor risk genotypes had a main effect on blood pressure in mothers or children. However, each 2-μg/m3 increase of four-year average PM2.5 was associated with a 16.3 (95%CI: 5.7, 26.9) mmHg higher diastolic blood pressure in mothers with the APOL1 high-risk genotype, while the estimated effect was much smaller in mothers with the low-risk genotype (i.e., 2.9 [95%CI: -3.1, 8.8] mmHg; Pinteraction = 0.01). Additionally, the associations of APOL1 risk alleles and the high-risk genotype with high blood pressure (i.e., SBP and/or DBP ≥ 90th percentile) were stronger in girls vs. boys (Pinteraction = 0.02 and 0.005, respectively).

CONCLUSION

This study sheds light on the distribution of high blood pressure by APOL1 genetic variants and informs regulatory policy to protect vulnerable population subgroups.

Genetics in chronic kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Numerous genes for monogenic kidney diseases with classical patterns of inheritance, as well as genes for complex kidney diseases that manifest in combination with environmental factors, have been discovered. Genetic findings are increasingly used to inform clinical management of nephropathies, and have led to improved diagnostics, disease surveillance, choice of therapy, and family counseling. All of these steps rely on accurate interpretation of genetic data, which can be outpaced by current rates of data collection. In March of 2021, Kidney Diseases: Improving Global Outcomes (KDIGO) held a Controversies Conference on "Genetics in Chronic Kidney Disease (CKD)" to review the current state of understanding of monogenic and complex (polygenic) kidney diseases, processes for applying genetic findings in clinical medicine, and use of genomics for defining and stratifying CKD. Given the important contribution of genetic variants to CKD, practitioners with CKD patients are advised to "think genetic," which specifically involves obtaining a family history, collecting detailed information on age of CKD onset, performing clinical examination for extrarenal symptoms, and considering genetic testing. To improve the use of genetics in nephrology, meeting participants advised developing an advanced training or subspecialty track for nephrologists, crafting guidelines for testing and treatment, and educating patients, students, and practitioners. Key areas of future research, including clinical interpretation of genome variation, electronic phenotyping, global representation, kidney-specific molecular data, polygenic scores, translational epidemiology, and open data resources, were also identified.

Sickle cell nephropathy: insights into the pediatric population

The life expectancy of individuals with sickle cell disease has increased over the years, majorly due to an overall improvement in diagnosis and medical care. Nevertheless, this improved longevity has resulted in an increased prevalence of chronic complications such as sickle cell nephropathy (SCN), which poses a challenge to the medical care of the patient, shortening the lifespan of patients by 20-30 years. Clinical presentation of SCN is age-dependent, with kidney dysfunction slowly beginning to develop from childhood, progressing to chronic kidney disease and kidney failure during the third and fourth decades of life. This review explores the epidemiology, pathology, pathophysiology, clinical presentation, and management of SCN by focusing on the pediatric population. It also discusses the factors that can modify SCN susceptibility.

APOL1 Renal Risk Variants and Kidney Function in HIV-1–Infected People From Sub-Saharan Africa

Introduction

APOL1 G1 and G2 alleles have been associated with kidney-related outcomes in people living with HIV (PLHIV) of Black African origin. No APOL1-related kidney risk data have yet been reported in PLHIV in West Africa, where high APOL1 allele frequencies have been observed.

Methods

We collected clinical data from PLHIV followed in Burkina Faso (N = 413) and in the ANRS-12169/2LADY trial (Cameroon, Senegal, Burkina Faso, N = 369). APOL1 G1 and G2 risk variants were genotyped using TaqMan assays, and APOL1 high-risk (HR) genotype was defined by the carriage of 2 risk alleles.

Results

In West Africa (Burkina Faso and Senegal), the G1 and G2 allele frequencies were 13.3% and 10.7%, respectively. In Cameroon (Central Africa), G1 and G2 frequencies were 8.7% and 8.9%, respectively. APOL1 HR prevalence was 4.9% in West Africa and 3.4% in Cameroon. We found no direct association between APOL1 HR and estimated glomerular filtration rate (eGFR) change over time. Nevertheless, among the 2LADY cohort participants, those with both APOL1 HR and high baseline viral load had a faster eGFR progression (β = −3.9[−7.7 to −0.1] ml/min per 1.73 m² per year, P < 0.05) than those with low-risk (LR) genotype and low viral load.

Conclusion

Overall, the APOL1 risk allele frequencies in PLHIV were higher in the West African countries than in Cameroon, but much lower than previously reported in some Nigeria ethnic groups, which strongly advocates for further investigation in the African continent. This study suggested that the virological status could modulate the APOL1 impact on kidney function, hence reinforcing the need for early therapeutic interventions.

The evolving story of apolipoprotein L1 nephropathy: the end of the beginning

Genetic coding variants in APOL1, which encodes apolipoprotein L1 (APOL1), were identified in 2010 and are relatively common among individuals of sub-Saharan African ancestry. Approximately 13% of African Americans carry two APOL1 risk alleles. These variants, termed G1 and G2, are a frequent cause of kidney disease — termed APOL1 nephropathy — that typically manifests as focal segmental glomerulosclerosis and the clinical syndrome of hypertension and arterionephrosclerosis. Cell culture studies suggest that APOL1 variants cause cell dysfunction through several processes, including alterations in cation channel activity, inflammasome activation, increased endoplasmic reticulum stress, activation of protein kinase R, mitochondrial dysfunction and disruption of APOL1 ubiquitinylation. Risk of APOL1 nephropathy is mostly confined to individuals with two APOL1 risk variants. However, only a minority of individuals with two APOL1 risk alleles develop kidney disease, suggesting the need for a ‘second hit’. The best recognized factor responsible for this ‘second hit’ is a chronic viral infection, particularly HIV-1, resulting in interferon-mediated activation of the APOL1 promoter, although most individuals with APOL1 nephropathy do not have an obvious cofactor. Current therapies for APOL1 nephropathies are not adequate to halt progression of chronic kidney disease, and new targeted molecular therapies are in clinical trials.

This Review summarizes current understanding of the role of APOL1 variants in kidney disease. The authors discuss the genetics, protein structure and biological functions of APOL1 variants and provide an overview of promising therapeutic strategies.

In contrast to other APOL family members, which are primarily intracellular, APOL1 contains a unique secretory signal peptide, resulting in its secretion into plasma.

APOL1 renal risk alleles provide protection from African human trypanosomiasis but are a risk factor for progressive kidney disease in those carrying two risk alleles.

APOL1 risk allele frequency is ~35% in the African American population in the United States, with ~13% of individuals having two risk alleles; the highest allele frequencies are found in West African populations and their descendants.

Cell and mouse models implicate endolysosomal and mitochondrial dysfunction, altered ion channel activity, altered autophagy, and activation of protein kinase R in the pathogenesis of APOL1-associated kidney disease; however, the relevance of these injury pathways to human disease has not been resolved.

APOL1 kidney disease tends to be progressive, and current standard therapies are generally ineffective; targeted therapeutic strategies hold the most promise.

Association of circulating fibroblast growth factor-2 with progression of HIV-chronic kidney diseases in children

BACKGROUND

Children living with HIV frequently show high plasma levels of fibroblast growth factor-2 (FGF-2/bFGF). FGF-2 accelerates the progression of several experimental kidney diseases; however, the role of circulating FGF-2 in childhood HIV-chronic kidney diseases (HIV-CKDs) is unknown. We carried out this study to determine whether high plasma FGF-2 levels were associated with the development of HIV-CKDs in children.

METHODS

The plasma and urine FGF-2 levels were measured in 84 children (< 12 years of age) living with HIV during the pre-modern antiretroviral era, and followed for at least 3 years to determine the prevalence of proteinuria and HIV-CKDs. We also assessed the distribution of the kidney FGF-2 binding sites by autoradiography and Alcian blue staining, and explored potential mechanisms by which circulating FGF-2 may precipitate HIV-CKDs in cultured kidney epithelial and mononuclear cells derived from children with HIV-CKDs.

RESULTS

High plasma FGF-2 levels were associated with a high viral load. Thirteen children (~ 15%) developed HIV-CKDs and showed a large reservoir of FGF-2 low-affinity binding sites in the kidney, which can facilitate the recruitment of circulating FGF-2. Children with high plasma and urine FGF-2 levels had 73-fold increased odds (95% CI 9-791) of having HIV-CKDs relative to those with normal FGF-2 values. FGF-2 induced the proliferation and decreased the expression of APOL-1 mRNA in podocytes, and increased the attachment and survival of infected mononuclear cells cultured from children with HIV-CKDs.

CONCLUSIONS

High plasma FGF-2 levels appear to be an additional risk factor for developing progressive childhood HIV-CKDs.

APOL1 Renal Risk Variants and Sickle Cell Trait Associations With Reduced Kidney Function in a Large Congolese Population-Based Study

Introduction

Methods

Results

Conclusion

Clinical and genetic factors are associated with kidney complications in African children with sickle cell anaemia

Clinical and genetic factors have been reported as influencing the development of sickle cell nephropathy (SCN). However, such data remain limited in the paediatric population. In this cross-sectional study, we enrolled 361 sickle cell disease children from the Democratic Republic of Congo. Participants were genotyped for the beta (β)-globin gene, apolipoprotein L1 (APOL1) risk variants, and haem oxygenase-1 (HMOX1) GT-dinucleotide repeats. As markers of kidney damage, albuminuria, hyperfiltration and decreased estimated glomerular filtration with creatinine (eGFRcr) were measured. An association of independent clinical and genetic factors with these markers of kidney damage were assessed via regression analysis. Genetic sequencing confirmed sickle cell anaemia in 326 participants. Albuminuria, hyperfiltration and decreased eGFRcr were present in 65 (20%), 52 (16%) and 18 (5·5%) patients, respectively. Regression analysis revealed frequent blood transfusions, indirect bilirubin and male gender as clinical predictors of SCN. APOL1 high-risk genotype (G1/G1, G2/G2 and G1/G2) was significantly associated with albuminuria (P = 0·04) and hyperfiltration (P = 0·001). HMOX1 GT-dinucleotide long repeats were significantly associated with lower eGFRcr. The study revealed a high burden of kidney damage among Congolese children and provided evidence of the possible role of APOL1 and HMOX1 in making children more susceptible to kidney complications.

Childhood HIV-associated nephropathy: 36 years later

HIV-associated nephropathy (HIVAN) predominantly affects people of African ancestry living with HIV who do not receive appropriate antiretroviral therapy (ART). Childhood HIVAN is characterized by heavy proteinuria and decreased kidney function. Kidney histology shows mesangial expansion, classic or collapsing glomerulosclerosis, and microcystic renal tubular dilatation leading to kidney enlargement. The pathogenesis of HIVAN involves the kidney recruitment of inflammatory cells and the infection of kidney epithelial cells. In addition, both viral and genetic factors play key roles in this disease. Modern ART has improved the outcome and decreased the prevalence of childhood HIVAN. However, physicians have had modest success providing chronic ART to children and adolescents, and we continue to see children with HIVAN all over the world. This article discusses the progress made during the last decade in our understanding of the pathogenesis and treatment of childhood HIVAN, placing particular emphasis on the mechanisms that mediate the infection of kidney epithelial cells, and the roles of cytokines, the HIV-Tat gene, and the Apolipoprotein-1 (APOL1) gene risk variants in this disease. In view of the large number of children living with HIV at risk of developing HIVAN, better prevention and treatment programs are needed to eradicate this disease.

APOL1 in an ethnically diverse pediatric population with nephrotic syndrome: implications in focal segmental glomerulosclerosis and other diagnoses

BACKGROUND

APOL1 high-risk genotypes (HRG) are associated with increased risk of kidney disease in individuals of African ancestry. We analyzed the effects of APOL1 risk variants on an ethnically diverse Brazilian pediatric nephrotic syndrome (NS) cohort.

METHODS

Multicenter study including 318 NS patients, categorized as progressors to advanced CKD [estimated glomerular filtration rate (eGFR)] < 30 mL/min/1.73 m²] and slow/non-progressors (eGFR > 30 mL/min/1.73 m² through the study). We employed Cox regression with progression time as the outcome and APOL1 genotype as the independent variable. We tested this association in the entire cohort and three subgroups; (1) focal segmental glomerulosclerosis (FSGS), (2) steroid-resistant NS (SRNS), and (3) those who underwent kidney biopsy.

RESULTS

Nineteen patients (6%) had an HRG. Of these, 47% were self-reported White. Patients with HRG manifested NS at older ages and presented higher frequencies of FSGS and SRNS. HRG patients progressed to advanced CKD more often than low-risk-genotype (LRG) children in the whole NS cohort (p = 0.001) and the three subgroups. In SRNS and biopsied patients, a single risk variant was associated with trends of higher CKD progression risk.

CONCLUSIONS

Novel discoveries include a substantial prevalence of HRG among patients self-reported White, worse kidney outcomes in HRG versus LRG children in the FSGS subgroup, and a trend of higher CKD progression risk associated with a single risk variant in the SRNS cohort. These findings suggest APOL1-associated NS extends beyond patients self-reported non-White, the HRG effect is independent of FSGS, and a single risk variant may have a detrimental impact in children with NS.

Novel Human Podocyte Cell Model Carrying G2/G2 APOL1 High-Risk Genotype

Apolipoprotein L1 (APOL1) high-risk genotypes (HRG), G1 and G2, increase the risk of various non-diabetic kidney diseases in the African population. To date, the precise mechanisms by which APOL1 risk variants induce injury on podocytes and other kidney cells remain unclear. Trying to unravel these mechanisms, most studies have used animal or cell models created by gene editing. We developed and characterised conditionally immortalised human podocyte cell lines derived from urine of a donor carrying APOL1 HRG G2/G2. Following induction of APOL1 expression by polyinosinic-polycytidylic acid (poly(I:C)), we assessed functional features of APOL1-induced podocyte dysfunction. As control, APOL1 wild type (G0/G0) podocyte cell line previously generated from a Caucasian donor was used. Upon exposure to poly(I:C), G2/G2 and G0/G0 podocytes upregulated APOL1 expression resulting in podocytes detachment, decreased cells viability and increased apoptosis rate in a genotype-independent manner. Nevertheless, G2/G2 podocyte cell lines exhibited altered features, including upregulation of CD2AP, alteration of cytoskeleton, reduction of autophagic flux and increased permeability in an in vitro model under continuous perfusion. The human APOL1 G2/G2 podocyte cell model is a useful tool for unravelling the mechanisms of APOL1-induced podocyte injury and the cellular functions of APOL1.

Circulating fibroblast growth factor-2 precipitates HIV nephropathy in mice

People of African ancestry living with the human immunodeficiency virus-1 (HIV-1) are at risk of developing HIV-associated nephropathy (HIVAN). Children with HIVAN frequently show high plasma fibroblast growth factor-2 (FGF-2) levels; however, the role of circulating FGF-2 in the pathogenesis of childhood HIVAN is unclear. Here, we explored how circulating FGF-2 affected the outcome of HIVAN in young HIV-Tg26 mice. Briefly, we demonstrated that FGF-2 was preferentially recruited in the kidneys of mice without pre-existing kidney disease, precipitating HIVAN by activating phosphorylated extracellular signal-regulated kinase (pERK) in renal epithelial cells, without inducing the expression of HIV-1 genes. Wild-type mice injected with recombinant adenoviral FGF-2 (rAd-FGF-2) vectors carrying a secreted form of human FGF-2 developed transient and reversible HIVAN-like lesions, including proteinuria and glomerular enlargement. HIV-Tg26 mice injected with rAd-FGF-2 vectors developed more-significant proliferative and pro-fibrotic inflammatory lesions, similar to those seen in childhood HIVAN. These lesions were partially reversed by treating mice with the FGF/VEGF receptor tyrosine kinase inhibitor PD173074. These findings suggest that high plasma FGF-2 levels may be an independent risk factor for precipitating HIVAN in young children.

Diagnosis, Education, and Care of Patients with APOL1-Associated Nephropathy: A Delphi Consensus and Systematic Review

BACKGROUND

APOL1 variants contribute to the markedly higher incidence of ESKD in Blacks compared with Whites. Genetic testing for these variants in patients with African ancestry who have nephropathy is uncommon, and no specific treatment or management protocol for APOL1-associated nephropathy currently exists.

METHODS

A multidisciplinary, racially diverse group of 14 experts and patient advocates participated in a Delphi consensus process to establish practical guidance for clinicians caring for patients who may have APOL1-associated nephropathy. Consensus group members took part in three anonymous voting rounds to develop consensus statements relating to the following: (1) counseling, genotyping, and diagnosis; (2) disease awareness and education; and (3) a vision for management of APOL1-associated nephropathy in a future when treatment is available. A systematic literature search of the MEDLINE and Embase databases was conducted to identify relevant evidence published from January 1, 2009 to July 14, 2020.

RESULTS

The consensus group agreed on 55 consensus statements covering such topics as demographic and clinical factors that suggest a patient has APOL1-associated nephropathy, as well as key considerations for counseling, testing, and diagnosis in current clinical practice. They achieved consensus on the need to increase awareness among key stakeholders of racial health disparities in kidney disease and of APOL1-associated nephropathy and on features of a successful education program to raise awareness among the patient community. The group also highlighted the unmet need for a specific treatment and agreed on best practice for management of these patients should a treatment become available.

CONCLUSIONS

A multidisciplinary group of experts and patient advocates defined consensus-based guidance on the care of patients who may have APOL1-associated nephropathy.

A focus on the association of Apol1 with kidney disease in children

Individuals of African origin have an increased risk of developing various progressive chronic kidney diseases (CKD). This risk has been attributed to genetic variants (G1, G2) in apolipoprotein-L1 (APOL1) gene. In the pediatric population, especially in children affected by sickle cell disease (SCD), by human immunodeficiency virus (HIV), or with various glomerular diseases, APOL1 risk variants have been associated with the development of hypertension, albuminuria, and more rapid decline of kidney function. The present review focuses on existing APOL1-related epidemiological data in children with CKD. It also includes data from studies addressing racial disparities in CKD, the APOL1-related innate immunity, and the relationship between APOL1 and CKD and pathogenic pathways mediating APOL1-related kidney injury.

APOL1 Nephropathy: From Genetics to Clinical Applications

Rates of many types of severe kidney disease are much higher in Black individuals than most other ethnic groups. Much of this disparity can now be attributed to genetic variants in the apoL1 (APOL1) gene found only in individuals with recent African ancestry. These variants greatly increase rates of hypertension-associated ESKD, FSGS, HIV-associated nephropathy, and other forms of nondiabetic kidney disease. We discuss the population genetics of APOL1 risk variants and the clinical spectrum of APOL1 nephropathy. We then consider clinical issues that arise for the practicing nephrologist caring for the patient who may have APOL1 kidney disease.

Apolipoprotein L1 risk genotypes in Ghanaian patients with systemic lupus erythematosus: a prospective cohort study

Objective

Two apolipoprotein L1 (APOL1) risk variants (RV) are enriched in sub-Saharan African populations due to conferred resistance to Trypanosoma brucei. These variants associate with adverse renal outcomes by multiple causes including SLE. Despite emerging reports that SLE is common in Ghana, where APOL1 variant allelic frequencies are high, the regional contribution to SLE outcomes has not been described. Accordingly, this prospective longitudinal cohort study tested the associations between APOL1 high-risk genotypes and kidney outcomes, organ damage accrual and death in 100 Ghanaian patients with SLE.

Methods

This was a prospective cohort study of 100 SLE outpatients who sought care at Korle bu Teaching Hospital in Accra, Ghana. Adult patients who met 4 American College of Rheumatology criteria for SLE were genotyped for APOL1 and followed longitudinally for SLE activity as measured by the Safety of Estrogens in Lupus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) hybrid and organ injury as measured by the Systemic Lupus International Collaborating Clinics Damage Index (SDI) at baseline and every 6 months for 1 year. Outcomes of interest were kidney function, SDI and case fatality.

Results

Assuming a recessive inheritance, the APOL1 high-risk genotype (2RV) associated with end-stage renal disease (ESRD) at an OR of 14 (p=0.008). These patients accrued more SDI points particularly in renal and neurological domains. The SDI was 81.3% higher in 2RV patients compared with 0RV or 1RV patients despite no difference in SLE activity (p=0.01). After a 12-month period of observation, 3/12 (25%) of the 2RV patients died compared with 2/88 (2.3%) of the 0RV or 1RV carriers (OR=13.6, p=0.01). Deaths were due to end-stage kidney disease and heart failure.

Conclusion

APOL1 RVs were heritable risk factors for morbidity and mortality in this Ghanaian SLE cohort. Despite no appreciable differences in SLE activity, APOL1 high-risk patients exhibited progressive renal disease, organ damage accrual and a 13-fold higher case fatality.

HIV-Associated CKDs in Children and Adolescents

INTRODUCTION

Limited information is available describing the current prevalence of proteinuria and HIV-associated CKDs (HIV-CKDs) in children and adolescents living with HIV and receiving antiretroviral therapy in the United States.

METHODS

To address this issue, we performed a retrospective study of children and adolescents living with HIV who received medical care at Children's National Hospital in Washington, DC, between January 2012 and July 2019. Demographic data, clinical parameters (mode of HIV transmission, viral loads, CD4 cell counts, serum creatinine, glomerular filtration rate [GFR], plasma lipid levels, proteinuria, blood pressure, renal biopsies), and medical treatments, all done as a standard of clinical care, were collected and analyzed.

RESULTS

The majority of the 192 patients enrolled were of African descent (88%) and acquired HIV through vertical transmission (97%). The prevalence of all HIV-CKDs was 6%. Of these patients, 39% had intermittent or persistent proteinuria, and 7% percent had proteinuria with a mild decline in GFR (60-80 ml/min per 1.73 m2), and 6% had a mild decline in GFR without proteinuria. Documented hypertension was present in 6% of the patients, mainly in association with HIV-CKD. Patients with persistent proteinuria (3%) and biopsy-proven HIV-CKD had a slow but constant progression of their renal diseases.

CONCLUSIONS

The prevalence of persistent proteinuria and HIV-CKD was lower than that reported in previous studies conducted in the United States. However, intermittent proteinuria, mild reductions in GFR, and progression of established HIV-CKD were common findings in this group of patients with predominantly vertically acquired HIV who were receiving antiretroviral therapy.

Prevalence and Risk Factors of CKD in South Kivu, Democratic Republic of Congo: A Large-Scale Population Study

Background

The prevalence of chronic kidney disease (CKD) in African American individuals is high but whether this applies to native populations in sub-Saharan Africa is unclear.

Methods

In a cross-sectional study, we assessed the prevalence and risk factors of CKD in rural and urban adults in South Kivu, Democratic Republic of Congo. Glomerular filtration rate (GFR) was estimated using the CKD–Epidemiology Collaboration (CKD-EPI) equations based on serum creatinine (eGFRcr), cystatin C (eGFRcys), or both markers (eGFRcr-cys), without ethnic correction factor. CKD was defined as an eGFR <60 ml/min per 1.73 m² and/or albuminuria (albumin-to-creatinine ratio ≥30 mg/g).

Results

A total of 1317 participants aged 41.1 ± 17.1 years (730 rural, 587 urban) were enrolled. The prevalence of hypertension (20.2%; 95% confidence interval [CI], 18–22.3), diabetes mellitus (4.3%; 95% CI, 3.2–5.4) and obesity (8.9%; 95% CI, 7.4–10.5) was higher in urban than rural participants (all P < 0.05). HIV infection prevalence was 0.41% (95% CI, 0.05–0.78). The prevalence of eGFRcr <60 ml/min per 1.73 m² was 5.4% (95% CI, 4.2–6.7). The prevalence of albuminuria was 6.6% (95 % CI, 5.1–8.1). The overall prevalence of CKD was 12.2% (95% CI, 10.2–14.2) according to CKD-EPIcr. Factors independently associated with CKD-EPIcr were older age (adjusted odds ratio [aOR], 1.05 [1.04–1.07]), urban residence (aOR 1.86 [1.18–2.95]), female sex (aOR 1.66 [1.04–2.66]), hypertension (aOR 1.90 [1.15–3.12]), diabetes (aOR 2.03 [1.02–4.06]), and HIV infection (10.21 [2.75–37.85]). The results based on eGFRcys or eGFRcr-cys were largely consistent with the preceding.

Conclusion

Overall, the burden of CKD is substantial (>11%), predominantly in the urban area, and largely driven by classic risk factors (gender, aging, HIV, hypertension, and diabetes).

Chronic comorbidities in children and adolescents with perinatally acquired HIV infection in sub-Saharan Africa in the era of antiretroviral therapy

Globally, 1·7 million children are living with HIV, of which 90% are in sub-Saharan Africa. The remarkable scale-up of combination antiretroviral therapy has resulted in increasing numbers of children with HIV surviving to adolescence. Unfortunately, in sub-Saharan Africa, HIV diagnosis is often delayed with children starting antiretroviral therapy late in childhood. There have been increasing reports from low-income settings of children with HIV who have multisystem chronic comorbidities despite antiretroviral therapy. Many of these chronic conditions show clinical phenotypes distinct from those in adults with HIV, and result in disability and reduced quality of life. In this Review, we discuss the spectrum and pathogenesis of comorbidities in children with HIV in sub-Saharan Africa. Prompt diagnosis and treatment of perinatally acquired HIV infection is a priority. Additionally, there is a need for increased awareness of the burden of chronic comorbidities. Diagnostic and therapeutic strategies need to be collectively developed if children with HIV are to achieve their full potential.