Determinants of the haemoglobin level in patients with sickle cell disease living in sub-Saharan Africa: Major impact of the country of residence and independent effects of leucocyte and platelet counts and haemolysis.

The degree of anaemia in sickle cell disease (SCD) is a well-known contributor to morbidity and mortality. We aimed to explore the factors affecting haemoglobin (Hb) level in African SCD patients, considering haemolysis biomarkers (LDH and bilirubin level, and reticulocyte count), leucocyte and platelet counts and socio-demographic characteristics (gender, age group, country of residence and BMI). The research was part of the CADRE multinational cohort and involved 3699 SCD patients living in Mali, Senegal, Ivory Coast, Democratic Republic of Congo, Gabon and Cameroon: 2936 SS/Sß0, 587 SC and 176 Sß + patients with median Hb level of 8, 11.3 and 11.2 g/dL respectively (p < 0.001). In multivariate analysis conducted in 1394 SS/Sß0 patients, living in Cameroon, female gender, lower BMI, higher haemolysis markers (especially LDH) and higher leucocyte and platelet counts were independently associated with lower Hb level (all p < 0.05). In 497 SC and 156 Sß + patients, female gender (p < 0.001), lower BMI (p < 0.05) and higher platelet counts (p < 0.001) were independently associated with lower Hb level. Anaemia in African SCD patients is not only associated with haemolysis but also with the country of residence, lower BMI and leucocyte or platelet counts which might reflect inflammation related to infectious burden in the region.

Morbidity and Mortality Associated with COVID-19 and Acute Chest Syndrome in Sickle Cell Disease Patients.

SUMMARYCOVID-19 infection has emerged as a comorbidity that can significantly increase morbidity and mortality in sickle cell patients with ACS (acute thoracic/chest syndrome). The aim of our study was to assess COVID-19-related morbidity and mortality in sickle cell patients with ACS. This was a retrospective, descriptive study of patient records followed over a 36-month period from January 2020 to December 2022. The study was conducted at the national blood transfusion center in Dakar. The sex ratio (M/F) was 0.82. The median age was 26 (17-39) years. The most represented age group was between 21 and 30 years. Factors associated with death were: at baseline, SS genotype, presence of comorbidities (asthma, chronic obstructive pulmonary disease, viral hepatitis B, ischemic heart disease), osteonecrosis of the femoral head, and use of NSAIDs (non-steroidal anti-inflammatory drugs) at diagnosis of COVID-19; at the diagnosis of ACS associated with COVID-19, respiratory distress, hypoxia (Sa02 < 92%), creatininemia >18.5 mg/l, CRP >192 mg/l, lymphopenia; the therapeutic modalities associated with death were: transfusion of RBCs (packed red blood cells) and curative anticoagulation. This study shows that patients with comorbidities and/or chronic complications of sickle cell disease can develop severe forms of ACS associated with COVID 19, leading to death. Other factors linked to death, notably diagnostic and therapeutic, were also identified in the course of this study.

Enuresis and overactive bladder in sickle cell patients: a narrative review of the literature.

OBJECTIVE: The aim of this review is to clarify the prevalence, pathophysiology and clinical presentation of enuresis and overactive bladder in sickle cell patients. MATERIALS AND METHODS: This narrative review of the literature was conducted in March 2022 by running a search in PubMed, Embase, Scopus and Cochrane databases without publication date limitation, using the following keywords: enuresis or nocturia or overactive bladder or urinary incontinence or bedwetting and sickle cell. RESULTS: Eight cross-sectional studies were included, six of which had a non-sickle cell control population. The prevalence of enuresis in children and adolescents with sickle cell disease ranged from 20.3 to 49.4%. It decreased with age to 2.9% in adult sickle cell patients. Enuresis in sickle cell patients has been attributed to several causes, including lack of urine concentration with nocturnal polyuria, reduced bladder capacity, nocturnal bladder hyperactivity, sleep and/or respiratory disorders are likely causes of enuresis in sickle cell patients. The prevalence of overactive bladder is three times higher in sickle cell patients than in control groups. The latter is also observed three times more frequently in men who have had prior episodes of priapism. CONCLUSION: Enuresis and overactive bladder are common in sickle cell patients. Several mechanisms have been described to try to explain enuresis in sickle cell patients but overactive bladder seems to play a major role. Studies evaluating the efficacy of certain experimentally validated treatments must be carried out to improve the management of these complications which affect the quality of life of sickle cell patients.

Degree of anemia, indirect markers of hemolysis, and vascular complications of sickle cell disease in Africa.

The hyperhemolysis paradigm that describes overlapping "hyperhemolytic-endothelial dysfunction" and "high hemoglobin-hyperviscous" subphenotypes of sickle cell disease (SCD) patients is based on North American studies. We performed a transversal study nested in the CADRE cohort to analyze the association between steady-state hemolysis and vascular complications of SCD among sub-Saharan African patients. In Mali, Cameroon, and Ivory Coast, 2407 SCD patients (1751 SS or sickle ß-zero-thalassemia [Sß0], 495 SC, and 161 sickle ß+-thalassemia [Sß+]), aged 3 years old and over, were included at steady state. Relative hemolytic intensity was estimated from a composite index derived from principal component analysis, which included bilirubin levels or clinical icterus, and lactate dehydrogenase levels. We assessed vascular complications (elevated tricuspid regurgitant jet velocity [TRV], microalbuminuria, leg ulcers, priapism, stroke, and osteonecrosis) by clinical examination, laboratory tests, and echocardiography. After adjustment for age, sex, country, and SCD phenotype, a low hemoglobin level was significantly associated with TRV and microalbuminuria in the whole population and with leg ulcers in SS-Sß0 adults. A high hemolysis index was associated with microalbuminuria in the whole population and with elevated TRV, microalbuminuria, and leg ulcers in SS-Sß0 adults, but these associations were no longer significant after adjustment for hemoglobin level. In conclusion, severe anemia at steady state in SCD patients living in West and Central Africa is associated with elevated TRV, microalbuminuria, and leg ulcers, but these vascular complications are not independently associated with indirect markers of increased hemolysis. Other mechanisms leading to anemia, including malnutrition and infectious diseases, may also play a role in the development of SCD vasculopathy.

Arterial Stiffness Impairment in Sickle Cell Disease Associated With Chronic Vascular Complications: The Multinational African CADRE Study.

BACKGROUND: Although a blood genetic disease, sickle cell disease (SCD) leads to a chronic vasculopathy with multiple organ involvement. We assessed arterial stiffness in SCD patients and looked for associations between arterial stiffness and SCD-related vascular complications. METHODS: The CADRE (Coeur Artères et Drepanocytose, ie, Heart Arteries and Sickle Cell Disease) study prospectively recruited pediatric and adult SCD patients and healthy controls in Cameroon, Ivory Coast, Gabon, Mali, and Senegal. Patients underwent clinical examination, routine laboratory tests (complete blood count, serum creatinine level), urine albumin/creatinine ratio measure, and a measure of carotid-femoral pulse wave velocity (cf-PWV) and augmentation index (AI) at a steady state. The clinical and biological correlates of cf-PWV and AI were investigated by using a multivariable multilevel linear regression analysis with individuals nested in families further nested in countries. RESULTS: Included were 3627 patients with SCD and 943 controls. Mean cf-PWV was lower in SCD patients (7.5±2.0 m/s) than in controls (9.1±2.4 m/s, P<0.0001), and lower in SS-Sß(0) than in SC-Sß(+) phenotypes. AI, corrected for heart rate, increased more rapidly with age in SCD patients and was higher in SCD than in control adults. cf-PWV and AI were independently associated with age, sex, height, heart rate, mean blood pressure, hemoglobin level, country, and hemoglobin phenotype. After adjustment for these correlates, cf-PWV and AI were associated with the glomerular filtration rate and osteonecrosis. AI was also associated with stroke, pulmonary hypertension, and priapism, and cf-PWV was associated with microalbuminuria. CONCLUSIONS: PWV and AI are deeply modified in SCD patients in comparison with healthy controls. These changes are independently associated with a lower blood pressure and a higher heart rate but also with the hemoglobin phenotype. Moreover, PWV and AI are associated with several SCD clinical complications. Their prognostic value will be assessed at follow-up of the patients.

Pattern of chronic myeloid leukemia in the imatinib era in a Sub-Saharan African setting.

Chronic myeloid leukemia (CML) is an orphan disease in Africa because of the inaccessibility to specific treatment and the high cost of diagnosis and monitoring patients. The aim of this study was to report CML treatment response in a developing country in the tyrosine kinase inhibitor era. We conducted a longitudinal study of our cohort of CML patients. Socio-demographic, diagnosis, therapeutic, and treatment response parameters were studied. Sokal score, disease phase at diagnosis, delay from diagnosis to treatment, and treatment response were analyzed for their impact on survival. Fifty-five patients with a diagnosis of CML and who received treatment with imatinib for a minimum of 3 months were included in this study. Median follow-up was 170 patient-years. The sex ratio (M/F) was 1.62 and median age at diagnosis was 42 years. At diagnosis, 85.5 % of the patients were in chronic phase (CP), 12.7 % in accelerated phase (AP), and 1.8 % in blast crisis (BC). Sokal risk score distribution was as follows: low risk 29.8 %, intermediate risk 38.3 %, and high risk 31.9 %. Median time from first symptoms to first medical visit was 6.2 months and median time from first medical visit to cytogenetic and or molecular confirmation was 12.4 months. Mean delay time from first medical visit to imatinib initiation was 12.5 months (95 % CI 6.3-18.7). The complete hematologic response (CHR) at 3 months, the major cytogenetic response (MCR) at 12 months, and the major molecular response (MMR) at 24 months were respectively 82.4, 75, and 25 %. The 2-year overall survival rate was 81 %. Advanced phase at the diagnosis, discontinuation of imatinib therapy over 15 % of the time, lack of CHR at 3 months, lack of MCR at 12 months, and progression of the disease during imatinib therapy were associated with a risk of death (p ≤ 0.05). Our data confirm the improved prognosis of CML treated with imatinib in the setting of a developing country. However, response rates are lower than in developed countries, and additional efforts should be made to facilitate early diagnosis and improve access to TKI, treatment compliance, and regular molecular monitoring of patients.

Lymphocytic Lymphoma Transforming into Hodgkin Lymphoma in Sub-Saharan Africa: Case Report and Literature Review.

The Hodgkin variant Richter syndrome (HvRS) is an infrequent complication occurring in 1% of lymphocytic lymphoma/chronic lymphocytic leukemia patients. We report a case of HvRS diagnosed in Sub-Saharan Africa. A 63-year-old patient was consulted for the investigation of an abdominal mass that had been evolving for 5 years prior to admission. His history revealed night sweats, 13% weight loss in 3 months and persistent pruritis. Examination revealed bilateral cervical axillary and inguinal macroadenopathies, painless abdominal distension, pruritic lesions and WHO 2 PS. The blood count showed anemia at 9.5 g/dL. Histology revealed a lymphomatous proliferation of diffuse architecture, nodular in places, with Hodgkin and Sternberg cells associated with small lymphocytes, histiocytes and eosinophilic polymorphs. Immunohistochemistry showed CD20, PAX5, BCL2, CD5, CD23 and MYC positivity; Ki67 at 10% and cyclin D1, BCL6 and CD10 negativity; CD30 positivity on Hodgkin and Sternberg cells that remained CD20 negative; difficulty interpreting CD15; EBV positivity (EBERs); and CD3 and CD5 positivity on reactive T cells. CD138 and kappa and lambda light chains were non-contributory. The extension work-up classified the patient as Ann Arbor stage III B with a Hasenclever score of 3/7. This case illustrates the difficulties in diagnosing HvRS in our countries, where the number of haematopathologists is insufficient and the technical facilities are limited.

A Case of Rosai-Dorfman Disease Successfully Treated by Corticotherapy.

Rosai-Dorfman disease (RDD) is a benign histiocytic proliferation that results in nodal and extranodal involvements. It is a rare disease, with fewer than 1,000 cases reported in the literature, which explains its lack of knowledge by physicians and the lack of codified therapeutic strategies. We report the case of an 8-year-old girl who presented a rapidly progressive cervical lymph node mass; the diagnosis of RDD was made based on histology and immunohistochemistry. The patient was treated with oral corticosteroids at a dose of 1 mg/kg/d with a favorable outcome and no recurrence after one year of follow-up. This observation illustrates the clinical presentation and diagnosis of this rare clinicopathological entity. The prognosis and treatment options are also discussed.

Homozygous Sickle Cell Disease after Age of 40: Follow-Up of a Cohort of 209 Patients in Senegal, West Africa.

Objectives: The aim of this study was to describe the morbidity and mortality of homozygous sickle cell disease after the age of 40. Methods: This was a cohort study of 209 patients followed from 1994 to 2022. All hemoglobin electrophoresis-confirmed SS sickle cell patients over 40 years were included. A descriptive study of epidemiological, diagnostic, therapeutic, and evolutionary data was used to assess morbidity and mortality. Results: Sex ratio (M/F) was 0.6. Median age was 47 (41-75). According to morbidity, 95.1% had less than 3 vaso-occlusive crises/year. Acute anemia was the most frequent complication (52.63%). Chronic complications were noted in 32.5%. At diagnosis, mean hemoglobin was 8.1 g/dl ± 1.9, HbS was 86.5 ± 10, and HbF was 9.4 ± 7.6. Number of patients transfused was 66%. We noted that 8.1% of patients died, 29.2% were lost to follow-up, and 62.7% were still being followed up. The risk factors identified for death were geographical origin, comorbidity, high HbS, low HbF, and thrombocytosis. Conclusion: This study shows that homozygous SCD is increasingly becoming an adult disease and that it can be carried into old age in Africa. Advanced age over 40 is marked by an upsurge in chronic complications, making it essential to set up a screening program and to organize multidisciplinary follow-up.

Antiphospholipid antibodies and systemic scleroderma.

OBJECTIVE: Antiphospholipid antibodies (APLs) could be associated with an increased risk of vascular pathologies in systemic scleroderma. The aim of our study was to search for APLs in patients affected by systemic scleroderma and to evaluate their involvement in the clinical manifestations of this disease. MATERIALS AND METHODS: We conducted a cross-sectional descriptive study, from January 2009 until August 2010, with patients received at the Department of Dermatology (Dakar, Senegal). Blood samples were taken at the hematology laboratory and were analyzed for the presence of APLs. RESULTS: Forty patients were recruited. Various types of either isolated or associated APLs were found in 23 patients, i.e. 57.5% of the study population. The most frequently encountered antibody was IgG anti-ß2 GPI (37.5% of the patients), followed by anticardiolipins (17.5%) and lupus anticoagulants (5%). No statistically significant association of positive antiphospholipid-related tests to any of the scleroderma complications could be demonstrated. CONCLUSION: A high proportion of patients showing association of systemic scleroderma and APLs suggests the presence of a morbid correlation between these 2 pathologies. It would be useful to follow a cohort of patients affected by systemic scleroderma in order to monitor vascular complications following confirmation of the presence of antiphospholipid syndrome. CONFLICT OF INTEREST: None declared.

Clinical outcome and incidence of inhibitor development in severe hemophilia patients receiving low-dose prophylaxis: a 3-year follow-up study in Senegal, West Africa.

INTRODUCTION: In Africa, where access to diagnosis and treatment of hemophilia is the lowest in the world, prophylaxis is rarely used in preference to on-demand treatment. There are limited data of prophylaxis treatment from sub-Saharan Africa. The aim of this study was to evaluate clinical outcomes and inhibitor development in people with hemophilia receiving low-dose prophylaxis (LDP) in a sub-Saharan African setting. METHODS: We conducted a three-year prospective study. A once or twice weekly prophylaxis regimen of 25 IU/kg of rFVIIIFc or 30 IU/kg of rFIXFc was given to Hemophilia A and B, respectively. We evaluated clinical outcomes and inhibitors occurrence, determined by screening and titration using the Nijmegen technique. RESULTS: A total of 15 patients were included in the LDP regimen. The mean age was 6.3 years (1.5 - 10). A significant reduction was noted in the annualized bleeding rate, from 7.53 to 1.33 (p = 0.0001); the annualized joint bleeding rate passed from 3.6 to 1.4 (p = 0.001) and the proportion of severe bleeding, from 86.1% to 16.7% (p = 0.0001). The Hemophilia Joint Health Score (HJHS) moved from 9.6 to 3.4 (p = 0.0001) and the Functional Independence Score in Hemophilia (FISH) improved from 25.8 to 30.9 (p = 0.0001). School absenteeism decreased from 7.33% to 2.59%. Adherence to prophylaxis was 89.5% versus 60%. Consumption was 580 IU/kg/year versus 1254.6 IU/kg/year before and after prophylaxis, respectively. Incidence of inhibitors was 23% (3 /13 HA). CONCLUSION: The LDP in Hemophilia improves the clinical outcome without a surplus risk of inhibitor development. Using extended half-life clotting factor concentrates (CFCs) is better for prophylaxis in resource-limited countries, as they allow better compliance in treatment.

Evaluation of knowledge of priapism in sickle cell patients in Senegal.

PURPOSE: Erectile dysfunction is a dreadful complication of priapism especially with delay in diagnosis and management. The lack of awareness of priapism as a vaso-occlusive complication of sickle cell disease (SCD) is more concerning. The objective of this study was to evaluate the burden of priapism in adult Senegalese males adults with sickle cell disease. METHODS: A cross-sectional study was carried out amongst consecutive consenting males aged 18 years and older with SCD presenting to the in Haematology Department of the National Blood Transfusion Centre (Dakar, Senegal). All participants completed a questionnaire detailing knowledge on the definition of priapism, its association with SCD, consequences of untreated priapism and treatment options. RESULTS: A total of 219 participants completed the questionnaire. The mean age of the respondents was 27.1 years with a range of (18-54). Of the respondents, 78.5% (n = 172) did not have any knowledge of the term "priapism". After the term was explained, 38.4% (n = 84) thought that there may be a risk of developing priapism given the diagnosis of sickle cell disease. Among the participants, 41.5% (n = 91) reported having a history of priapism. Among all patients who experienced priapism, 36.3% (n = 33) did not seek medical attention with episodes of priapism. It was found that 48.4% (n = 106) of the participants thought there may be a risk of irreversible complications associated with priapism and a corresponding proportion, 42% (n = 92) thought this risk was time dependent. 36.5% (n = 80) of patients believed priapism could lead to erectile dysfunction. CONCLUSION: Priapism is a common complication of sickle cell disease in Senegalese adults which is not well known by sickle cell patients. The health authorities must undertake efforts to raise awareness of priapism as a complication amongst sickle cell patients.

Red blood cell alloantibodies in paediatric transfusion in sub-Saharan Africa: A new cohort and literature review.

Blood transfusion support predisposes transfused children to the risk of erythrocyte alloimmunization in Sub-Saharan Africa. A cohort of 100 children receiving one to five blood transfusions were recruited for screening and identification of irregular antibodies using gel filtration technique. The mean age was 8 years and the sex-ratio at 1.2. The retrieved pathologies were: major sickle cell anaemia (46%), severe malaria (20%), haemolytic anaemia (4%), severe acute malnutrition (6%), acute gastroenteritis (5%), chronic infectious syndrome (12%) and congenital heart disease (7%). The children presented with haemoglobin levels ≤6 g/dl, and 16% of them presented positive irregular antibodies directed against the Rhesus (30.76%) and Kell (69.24%) blood group systems. A literature review shows that irregular antibody screenings vary from 17% to 30% of transfused paediatric patients in Sub-Saharan Africa. These alloantibodies are in particular directed against the Rhesus, Kell, Duffy, Kidd and MNS blood group and generally found in sickle cell disease and malaria. This study highlights the urgent need of extended red blood cell phenotyping including typing for C/c, E/e, K/k, and Fya/Fyb, and if possible Jka/Jkb, M/N, and S/s for children before transfusion in Sub-Saharan Africa.

Life-threatening bleeding in patients with hemophilia (PWH): a 10-year cohort study in Dakar, Senegal.

OBJECTIVE: The aim of this study was to assess incidence, risk factors, treatment and outcome of LTB in Senegalese people with hemophilia (PWH). METHODS: We analyzed the characteristics of LTB in a cohort of 274 PWH after 10 years of follow-up. RESULTS: We included 274 patients (241 HA and 33 HB). The mean age was 16.45 years and the median age was 13 years. The mean annual bleeding rate (ABR) was 1.65 (2.83 for severe form, 1.54 for moderate form, and 1.22 for mild form). A replacement therapy with clotting factor concentrates (CFC) was administered to 217 patients (79.2%); 56 patients (20.4%) received low-dose prophylaxis (LDP). Prevalence of inhibitors was 4.7% (13/274). All patients were HIV and HCV antibody negative. We observed 31 cases of LTB in 22 patients with an incidence of 8.03%. Central nervous system (CNS) bleeds were most frequent (6.2%) and accounted for 54.8% of severe bleeding. The delay between the first signs and the emergency visit was 78.9 hours. Inhibitors were positive in one patient among those who presented LTB. These bleeding were treated with CFC in 16 patients, surgical drainage (1 patient) and electrocoagulation during gastroscopy (1 patient). Eleven patients had complete remission and two had sequelae. We reported 0.32 death per 100 person-years. CNS bleeds were the main cause (77.7%). Four patients were secondarily on LDP. We observed a significant correlation between treatment (after 2 hours) and mortality. CONCLUSION: LTB is a serious and lethal complication in PWH in absence of early management. A good awareness of patients and their family would further reduce this incidence, especially in resources-limited countries.

Smudge cells percentage on blood smear is a reliable prognostic marker in chronic lymphocytic leukemia.

OBJECTIVE: We evaluated the relevance of using the smudge cell percentage in the blood smear as a prognostic marker in CLL. METHODS: In this prospective study, 42 untreated Senegalese patients with CLL were enrolled. The diagnosis was established, based on the peripheral blood count and flow cytometry using the Matutes score. Cytogenetic aberrations, assessed by fluorescence in situ hybridization (FISH), were available for 30 patients, while the immunoglobulin heavy chain genes (IGVH) mutation status was performed by next-generation sequencing (NGS) in 24 patients. The SC percentage was determined in the blood smear, as previously described. Statistical analyses were executed using the GraphPad Prism 8. RESULTS: The mean age was 63 years (48 - 85) and the male: female sex ratio was 4.66. A low SC (< 30%) percentage was correlated with Binet stage B/C (p = 0.0009), CD38 expression (p = 0.039), unmutated IGVH status (p = 0.0009) and presence of cytogenetic abnormalities (for del 13q, p = 0.0012, while for other cytogenetic aberrations, p = 0.016). An inverse correlation was found between the SC percentage and the absolute lymphocyte count (r = -0.51) and patients with higher percentage of SCs had a prolonged survival. However, there was no correlation between the SC percentage and age (p = 0.41) or gender (median, 19% for males vs. 20% for females; p = 0.76). CONCLUSION: When less than 30%, the SC was associated with a poor prognosis in CLL. Easy and affordable, the percentage of SCs in a blood smear could be a reliable prognostic marker, accessible to all CLL patients, mainly those in developing countries.

Transfusion Practice, Post-Transfusion Complications and Risk Factors in Sickle Cell Disease in Senegal, West Africa.

CONTEXT AND OBJECTIVES: Blood transfusions (BT) remain a mainstay of therapy for patients with sickle cell disease (SCD) but pose significant clinical challenges. We aim to assess infectious markers, red cell alloimmunization, and iron overload secondary to BT in SCD patients. MATERIALS AND METHODS: This case-control study included 253 SCD (153 SCD-transfused and 100 SCD non-transfused). We evaluated the transfusion practice (modalities, indications), post-transfusion complications (infections, alloimmunization, iron overload), and risk factors of these complications (socio-demographic, clinical, biological). RESULTS: Median age was 28.5 years (5 - 59). The sex ratio was 0.86. Homozygous SCD was the most common (95.3%). Simple BT was performed in 92.8% and transfusion exchange in 18.9%. Transfusion indications were dominated by acute anemia (57.06%) and vaso-occlusive crisis (VOCs) (14%). Red blood cell concentrates (RBCSs) were administered to 93.46%. The median RBCs received per patient was 10 (2 - 48). The prevalence of VHC in SCD-transfused was 1.33% and 2% for VHB. Anti-HIV antibodies were not found. Red cell alloimmunization frequency was 16%. The most common alloantibodies were anti-rhesus (34.19%) and anti-Kell (23.67%). Iron overload was detected in 7.84%. The number of RBCs transfused was the only risk factor for alloimmunization (p = 0.03) and iron overload (p = 0.023). BT frequency was not related to infectious transmission. CONCLUSION: BT therapy is still a risk for SCD polytransfused patients despite advances in blood safety. Although infectious transmission has rare, the risk of alloimmunization and iron overload is high in these patients.

Effects of Senegal haplotype (Xmn1-rs7412844), alpha-thalassemia (3.7kb HBA1/HBA2 deletion), NPRL3-rs11248850 and BCL11A-rs4671393 variants on sickle cell nephropathy.

OBJECTIVE: Sickle cell anemia (SCA) can cause substantial kidney dysfunction resulting in sickle cell nephropathy, which may be affected by the presence of modifier genes. This study evaluates the effects of some modifier genes on sickle cell nephropathy. METHODS: Patients living with SCA were recruited. Alpha-thalassemia (3.7kb HBA1/HBA2 deletion) was genotyped using gap PCR multiplex. Senegal haplotype (Xmn1-rs7412844), BCL11A-rs4671393 and NPRL3-rs11248850 were genotyped using Mass Array. The effects of variants on kidney dysfunction were then evaluated using multivariate analysis. RESULTS: The number of patients living with SCA included in this study was 162 with a median age of 20 years [minimum-maximum: 4-57] and a female frequency of 53.21%. Senegal haplotype, BCL11A-rs4671393 variant were protective factors against albuminuria stage A2 with an odds ratio (OR) of 0.22 (95% CI 0.05-0.90) and 0.27 (95% CI 0.08-0.96) respectively. The combination NPRL3-rs11248850 variant - 3.7kb HBA1/HBA2 deletion was a protective factor against albuminuria stage A2 (OR = 0.087, 95% Cl 0.01-0.78) but it was a risk factor for glomerular hyperfiltration (OR = 17.69, 95% CI 1.85-169.31). CONCLUSIONS: All four variants displayed a protective effect against albuminuria stage A2. The combination alpha-thalassemia - NPRL3-rs11248850 variant is a risk factor for glomerular hyperfiltration.

Biomarkers of sickle cell nephropathy in Senegal.

Sickle cell anemia (SCA) is caused by a single point variation in the ß-globin gene (HBB): c.20A> T (p.Glu7Val), in homozygous state. SCA is characterized by sickling of red blood cells in small blood vessels which leads to a range of multiorgan complications, including kidney dysfunction. This case-control study aims at identifying sickle cell nephropathy biomarkers in a group of patients living with SCA from Senegal. A total of 163 patients living with SCA and 177 ethnic matched controls were investigated. Biological phenotyping included evaluation of glycemia, glucosuria, albuminuria, proteinuria, tubular proteinuria, serum creatinine, urine creatinine, urine specific gravity and glomerular filtration rate. Descriptive statistics of biomarkers were performed using the χ2 -test, with the significance level set at p<0.05. Patients living with SCA had a median age of 20 years (range 4 to 57) with a female sex frequency of 53.21%. The median age of the control participants was 29 years (range: 4-77) with a female sex frequency of 66.09%. The following proportions of abnormal biological indices were observed in SCA patients versus (vs.) controls, as follows: hyposthenuria: 35.3%vs.5.2% (p<0.001); glomerular hyperfiltration: 47.66%vs.19.75% (p<0.001), renal insufficiency: 5.47%vs.3.82% (p = 0.182); microalbuminuria: 42.38%vs.5.78% (p<0.001); proteinuria: 39.33%vs.4.62% (p<0.001); tubular proteinuria: 40.97%vs.4.73% (p<0.001) and microglucosuria: 22.5%vs.5.1% (p<0.001). This study shows a relatively high proportion of SCA nephropathy among patients living with SCA in Senegal. Microglucosuria, proteinuria, tubular proteinuria, microalbuminuria, hyposthenuria and glomerular hyperfiltration are the most prevalent biomarkers of nephropathy in this group of Senegalese patients with SCA.