A study for the role of apolipoprotein-1 gene haplotypes as a genetic predictor of renal dysfunction among pediatric Egyptian sickle cell disease patients

Background: Sickle cell nephropathy (SCN) is linked with significant morbidity and mortality. SCN is first presented as glomerular hyperfiltration then it progresses to focal segmental glomerular sclerosis, and eventually, renal failure. SCN can be assessed by the presence of albuminuria, measuring estimated glomerular filtration rate (eGFR), abnormalities in kidney biopsy and/or imaging, and. SCN was linked to different gene polymorphisms such as the apolipoprotein-1 (APOL-1) gene two haplotypes; G1 (G1GM and G1G+ sub- haplotypes) and G2. Aim: Determination of the prevalence of APOL-1 among SCD Egyptian pediatric patients and its role as a genetic predictor of renal dysfunction in SCD pediatric patients. Methods: In this cross-sectional study, 69 patients with sickle cell anemia (SCA) and 28 patients with S/β thalassemia patients, and 3 sickle trait patients underwent full history taking, clinical examination, and laboratory tests including CBC, Hb electrophoresis, serum creatinine (and calculation of eGFR using “bedside Schwartz” formula), microalbuminuria, urine albumin/ creatinine ratio and genomic DNA analysis for detection of APOL-1 G1 SNPs S342G and I384M using PCR- RFLP analysis. Results: The prevalence of APOL-1 G1 variants among our patients was 44% (44 patients); 23% of them had G1GM sub-haplotype (10% of SCD patients) and 77% of them had G1G+ sub-haplotype (34% of SCD patients). Among the 17 cases of microalbuminuria, 9 cases (53%) had G1 variants. Hyperfiltration cases were 10 cases of which 7 cases (70%) had the G1 variants, 13 out of the 30 cases (43.3%) of mildly decreased eGFR had G1 variants and the two cases of mild to moderately decreased eGFR (100%) had G1 variant; the G1GM sub-haplotype. There was no significant association between the APOL-1 G1 variant in total and the chronic renal complications of SCD in the studied patients. There was no significant association between G1GM sub-haplotype and the earlier stages of chronic kidney disease as hyperfiltration and mildly decreased eGFR. A significant association was found between G1GM sub-haplotype and later stages of chronic kidney disease; as microalbuminuria (P=0.026) and mildly to moderately decreased eGFR (P=0.020). Conclusion: The prevalence of APOL-1 G1 variants in our study was 44% with a higher prevalence of G1G+ sub-haplotype (34%) than G1GM sub-haplotype (10%). There is a significant association between having G1GM sub-haplotype and chronic renal complications; as microalbuminuria and mildly to moderately decreased eGFR, thus, APOL-1 risk variant G1GM was associated with more severe stages of chronic kidney disease, indicating a more prominent association with SCN progression. Keywords: Sickle cell disease, nephropathy, albuminuria, estimated glomerular filtration rate, APOL-1, G1 variants.

Cell-Free Hemoglobin, HMOX1 and APOL1 in Sickle Cell Nephropathy

Alterations in the Humoral Immunophenotype of Children with Sickle Cell Disease on Hydroxyurea

Association between plasma and urinary orosomucoid and chronic kidney disease in adults with sickle cell disease.

A Comparison of Two Pain Assessment Tools, the Adolescent Pediatric Pain Tool and PAINReportIt and Use of the Composite Pain Index in Sickle Cell Disease

Sickle cell disease (SCD) is a monogenic disease associated with multisystem morbidity. Vasculopathy caused by delicate imbalance between coagulation and endothelial systems plays a pivotal role in disease course. As Protein Z and Endothelin-1 genetic polymorphisms may increase the thrombotic risk, the aim of the current work was to verify the possible impact of Protein Z (PROZ G79A) and Endothelin-1 (EDN1 G5665T) polymorphisms on the clinic-laboratory features of the SCD in a cohort of Egyptian pediatric patients. Genotyping of Protein Z G79A and Endothelin-1 G5665T was carried out by polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP) assay for 100 SCD patients and 100 controls. Protein -Z G79A polymorphism was not associated with vascular complications in the studied SCD patients. Endothelin-1 G5665T polymorphism was associated with pulmonary dysfunction (pulmonary artery hypertension and acute chest syndrome) and severe vaso-occlusive crises (VOC). Endothelin-1 G5665T polymorphism could be considered as a molecular predictor for pulmonary dysfunction and severe VOC in SCD. Further researches with larger cohorts are recommended to understand the pathophysiology of SCD and to explain the inter-patients' variability of disease severity.

In patients with diabetes mellitus, hyperfiltration precedes the development of albuminuria. Pediatric sickle cell anemia (SCA) patients have a high prevalence of hyperfiltration and albuminuria during early childhood and adolescence. We tested the hypothesis that hyperfiltration precedes the development of albuminuria in a longitudinal pediatric SCA cohort. We identified 91 participants with HbSS or SB0 thalassemia 5-21 years of age enrolled in a longitudinal sickle cell nephropathy cohort study who had a cystatin C measured during early childhood (4-10 years of age). Early hyperfiltration was defined as a mean eGFR >180 mL/min/1.73m2 using cystatin C obtained from 4 to 10 years of age. Persistent albuminuria was defined as an albumin to creatinine ratio > 30 mg/g on two of three untimed urine specimens. Time to event analysis estimated survival curves for participants with and without hyperfiltration using Kaplan-Meier curves and used logrank test for categorical variables to assess the association with time to development of the first episode persistent albuminuria. Persistent albuminuria occurred more often and at an earlier age in participants with early hyperfiltration compared to those without early hyperfiltration (log-rank, P = .004). Participants who developed albuminuria have a significant increase in their eGFR during childhood (P = .003) as compared to participants who have not yet progressed to albuminuria (P = .26). For every 1 g/dL increase in hemoglobin, the hazard ratio for developing persistent proteinuria decreased by 0.56 (95% CI: 0.3, 1.06, P = .07). Hyperfiltration precedes the development of persistent proteinuria in pediatric SCA patients. Intervention strategies should target lowering eGFR during early childhood.

Identification of Patient-Specific Factors Associated with Alloimmunization in Sickle Cell Disease

Presentation Date: 6/9/2024 Presentation Start Time: 3:15:00 PM Background The American Society of Hematology (ASH) recommendations for management of sickle cell disease (SCD) emphasize starting prescription medications in early childhood to modify the disease course. However, access barriers like transportation, long pharmacy wait-times, cost concerns, and complex medication regimens can hinder medication adherence and subsequently impact desired patient outcomes. Published reports on medication adherence in pediatric SCD prior to 2020 found Medication Possession Ratio (MPR) ranged from 49% to 74% for hydroxyurea. Deferasirox iron chelation MPR has been reported at 44% for pediatric SCD and beta thalassemia. MPR > 80% for hydroxyurea is associated with positive outcomes in SCD. The COVID pandemic further impaired medication adherence, and clinic follow up. A tertiary medical center adapted its pharmacy services in 2020 to address the challenges in medication adherence. A home medication delivery service was introduced through a Specialty Pharmacy unit (SP) in April 2020 to ensure patients, such as pediatric SCD patients, could access their medications during COVID isolation. Clinical pharmacists also made regular telephone contact with families. SP has continued these services after COVID restrictions were relaxed. This retrospective study evaluates how the service offered by SP affects medication adherence and follow-up visit compliance among its pediatric SCD population. Methods This retrospective quality assessment was conducted in January 2024. The inclusion criteria were SCD patients aged 0 to 20 years old who utilized UI Health SP’s home medication delivery service for at least one chronic disease-modifying medication between 2020 and 2023. Data were collected by SP clinical pharmacy team on the following four medications managed by the SP: Hydroxyurea, Voxelotor, L- glutamine and Deferasirox film-coated tablets. Quantitative data was collected by a retrospective chart review of medication delivered, clinic appointments kept, and laboratory monitoring fetal hemoglobin (HbF) and Mean Corpuscular Volume (MCV) results. The SP pharmacists assessed medication compliance based on dispense history and scheduled mail order medication refills to calculate MPR. They used a daily calendar to monitor patients’ schedules for home delivery. Noncompliance was identified if patients missed three or more medication refills within one year. Qualitative data were collected from the family caregivers by questionnaires and interviews conducted via telephone or face-to-face sessions at the pediatric sickle cell clinic. Results A total of 81 pediatric SCD patients met eligibility criteria, although 8 had some gaps in use of SP. Participants were taking either one or two of the study medications. Each medication was studied from April 2020 to December 2023. Of these patients, 39 were male (48%). About 90% reside in the same county as the tertiary med center. Medication Possession Ratio: Among eligible pediatric SCD patients, Siklos Hydroxyurea had perfect compliance, with MPR 100% (n = 14). Hydroxyurea suspension showed a high MPR of 91.75% (n = 36), indicating good adherence among most patients. L-glutamine had MPR 87% (n = 22) and voxelotor 87.3% (n = 8), also indicating relatively good adherence. However, Deferasirox had the lowest compliance rate at 75% (n = 2). Lab response: Good compliance with Hydroxyurea had the expected increase in their HbF and MCV levels for those with genotypes SS and S-beta-zero-thalassemia (n = 78). The three with genotype SC and did not show any increase in their HbF levels. Qualitative Results Participants generally agreed that the service made medication management easier, minimized ED visits and hospitalization, and overall reduced the possibility of SCD complications. Strong follow-up by the team of pharmacy staff and clinicians was noted to be one of the measures that improved compliance. Conclusions Overall, service through SP is associated with MPR over the benchmark 80% associated with improved SCD patient outcomes for hydroxyurea. These MPR rates are like the results reported from other interventions to enhance medication adherence in SCD. MPR challenges remains with medications like Deferasirox. Although the study is a quality assessment rather than a randomized trial, these findings suggest that the Specialty Pharmacy’s tailored interventions and ongoing support do optimize medication adherence in pediatric SCD patients compared to simply dispensing prescriptions for families to pick up. The home medication delivery service has potential to address access barriers. Future work could build these collaborations with Specialty Pharmacies to ensure comprehensive care for pediatric SCD patients and mitigate the impact of this chronic condition on their health and well-being.

Sickle cell nephropathy is a recognized complication increasingly seen in young individuals with sickle cell disease (SCD). The typical progression of glomerular disease is thought to involve hyperfiltration and albuminuria, eventually leading to a decline in glomerular filtration rates and ultimately end-stage renal disease (ESRD). This study sought to investigate the relationship between urinary interleukin-1 beta (IL-1β), a marker of inflammation, and existing biomarkers of renal damage in SCD patients. The goal was to identify IL-1β as a novel, early diagnostic biomarker for sickle nephropathy. This case-control study enrolled forty-six patients (both genders, aged 18-40 years) with sickle cell disease and forty-six healthy controls. All patients were subjected to the following: A complete medical history, physical examination, and laboratory investigation including a complete blood analysis, blood chemistry (which included kidney function tests and liver function, serum ferritin, urinalysis, hepatitis B surface antigen and hepatitis C antibody, estimated GFR, urinary IL-1 beta using the ELISA technique, and urinary albumin/creatinine ratio). These measurements were taken for both the case and control groups. The mean estimated glomerular filtration rate (eGFR) level showed a statistically significant increase in SCD patients. The median value of the albumin/creatinine ratio level was statistically different between cases and controls. The median value of urinary IL-1 beta level was statistically different between cases and controls. Assessment of correlations between urinary IL-1 beta and eGFR revealed a statistically significant negative correlation between them, while assessment of the correlation between urinary IL-1 beta and the urinary albumin/creatinine ratio revealed a statistically significant positive correlation between them in sickle cell patients. In this study, significant renal hyperfiltration, a high frequency of albuminuria, and elevated urine IL-1β levels are all present in Egyptian adults with sickle cell disease. Urinary IL-1β, albuminuria, and eGFR are strongly correlated, highlighting the crucial role of inflammation in sickle cell nephropathy pathogenesis. A promising non-invasive biomarker for early renal injury and disease progression in sickle cell disease (SCD) may be urinary IL-1β.

Disparities In Pulmonary Complications of Sickle Cell Disease

Identification of ceruloplasmin as a biomarker of chronic kidney disease in urine of sickle cell disease patients by proteomic analysis.

In African-American patients with sickle cell disease (SCD), APOL1 G1 and G2 variants are associated with increased risk of sickle cell nephropathy (SCN). To determine the role of APOL1 variants in SCD patients living in Europe, we genotyped 152 SCD patients [aged 30·4 (24·3-36·4)years], mainly of Sub-Saharan African ancestry, for APOL1 G1 and G2 and for variants of four genes with kidney tropism (GSTM1, GSTT1, GSTP1, and HMOX1). Homozygous or double-heterozygous APOL G1 and G2 genotypes were strongly associated with end stage renal disease (P=0·003) and worse Kidney Disease: Improving Global Outcomes stages (P=0·001). Further, these genotypes were associated in an age-dependent manner with lower estimated glomerular filtration rate (eGFR, P=0·008), proteinuria (P=0·009) and albuminuria (P<0·001) but not with other SCD complications. Compared to APOL1 G1/wild type (WT), the APOL1 G2/WT genotype was associated with a lower eGFR (P=0·04) in an age-dependent manner, suggesting that the G2/WT patients are likely to have worse kidney prognosis. Other genes variants analysed were not associated with SCN or other SCD complications. Our data indicate that APOL1 screening should be considered for the management of SCD patients, including those of non-African-American origin, as those with homozygous or double heterozygous variants are clearly at higher risk of SCN.

Alternatively Spliced Tissue Factor (asTF) Is Elevated in the Plasma of Patients with Sickle Cell Disease: Pilot Studies Performed Using a Novel asTF-Specific ELISA

Sickle cell nephropathy (SCN) is a progressive disease that contributes significant morbidity and mortality in sickle cell disease (SCD), yet it remains poorly understood. Hyperuricemia negatively impacts renal function in the non-sickle cell population but is understudied in SCD. We performed a cross-sectional analysis of the first 78 pediatric SCD patients enrolled in a cohort study. The mechanism of development of hyperuricemia (defined, serum uric acid (UA) ≥ 5.5 mg/dL) was characterized as a result of either UA overproduction or inefficient renal excretion by the Simkin index and fractional clearance of urate (FCU) equations. Associations between hyperuricemia and albuminuria or estimated glomerular filtration rate (eGFR) were determined by linear regression. The prevalence of hyperuricemia in this young population (mean age 11.6 ± 3.77 years) was 34.2%. Only 1 hyperuricemic participant overproduced UA by Simkin index, while 62.5% were inefficient renal excretors of UA (FCU < 4%). Hyperuricemia was associated with a significant decrease in average eGFR, -27 ml/min/1.73m2 below normouricemia (mean eGFR 151.6 ± 40.32), p = 0.0122. Notably, the previously accepted association between decline of eGFR with age is significantly modified by hyperuricemia stratification, where hyperuricemia explains 44% of the variance in eGFR by age (R2 = 0.44, p = 0.0004) and is nonsignificant in normouricemia (R2 = 0.07, p = 0.0775). These findings indicate that hyperuricemia may be associated with early eGFR decline in SCN. This association must be further characterized in prospective cohort studies in SCN, and hyperuricemia must be investigated as a potential therapeutic target for SCN.