Systematic Review of Genetic Modifiers Associated with the Development and/or Progression of Nephropathy in Patients with Sickle Cell Disease.

Sickle cell nephropathy (SCN) is a common complication of sickle cell disease (SCD) that significantly contributes to morbidity and mortality. In addition to clinical and life-style factors, genetic variants influence this risk. We performed a systematic review, searching five databases. Studies evaluating the effect of genetic modifiers on SCN were eligible. Twenty-eight studies (fair-to-good quality) were included: one genome-wide association study, twenty-six case-control studies, and one article combining both approaches. APOL1 was significantly associated with albuminuria and hyperfiltration in children and with worse glomerular filtration in adults. On the other hand, alpha-thalassemia protected patients against albuminuria and hyperfiltration, while BCL11A variants were protective against albuminuria alone. The HMOX1 long GT-tandem repeat polymorphism led to a lower glomerular filtration rate. No modifiers for the risk of hyposthenuria were identified. A genome-wide association approach identified three new loci for proteinuria (CRYL1, VWF, and ADAMTS7) and nine loci were linked with eGFR (PKD1L2, TOR2A, CUBN, AGGF1, CYP4B1, CD163, LRP1B, linc02288, and FPGT-TNNI3K/TNNI3K). In conclusion, this systematic review supports the role of genetic modifiers in influencing the risk and progression of SCN. Incorporating and expanding this knowledge is crucial to improving the management and clinical outcomes of patients at risk.

Assent, parental consent and reconsent for health research in Africa: thematic analysis of national guidelines and lessons from the SickleInAfrica registry.

The enrolment of children and adolescents in health research requires that attention to be paid to specific assent and consent requirements such as the age range for seeking assent; conditions for parental consent (and waivers); the age group required to provide written assent; content of assent forms; if separate assent and parental consent forms should be used, consent from emancipated young adults; reconsent at the age of adulthood when a waiver of assent requirements may be appropriate and the conditions for waiving assent requirements. There is however very little available information for researchers and ethics committees on how to navigate these different issues. To provide guidance to research initiatives, the SickleInAfrica consortium conducted a thematic analysis of a sample of research ethics guidelines and procedures in African countries, to identify guidance for assent requirements in health research. The thematic analysis revealed that 12 of 24 African countries specified the age group for which assent is required. The minimum age for written assent varied across the countries. Five countries, Algeria, Botswana, Cameroon, Nigeria and The Democratic Republic of Congo require consent from both parents/family council in certain circumstances. Botswana, Nigeria, South Africa and Uganda have specific assent/consent requirements for research with emancipated minors. South Africa and Algeria requires re-consent at onset of adulthood. Five countries (Botswana, Cameroon, Nigeria, South Africa and Tanzania) specified conditions for waiving assent requirements. The CIOMS and the ICH-GCP guidelines had the most comprehensive information on assent requirements compared to other international guidelines. An interactive map with assent requirements for different African countries is provided. The results show a major gap in national regulations for the inclusion of minors in health research. The SickleInAfrica experience in setting up a multi-country SCD registry in Africa highlights the need for developing and harmonising national and international guidelines on assent and consent requirements for research involving minors. Harmonisation of assent requirements will help facilitate collaborative research across countries.

Sickle cell disease clinical phenotypes in Nigeria: A preliminary analysis of the Sickle Pan Africa Research Consortium Nigeria database.

BACKGROUND/OBJECTIVE: Sickle cell disease (SCD) is a monogenic disease with multiple phenotypic expressions. Previous studies describing SCD clinical phenotypes in Nigeria were localized, with limited data, hence the need to understand how SCD varies across Nigeria. METHOD: The Sickle Pan African Research Consortium (SPARCO) with a hub in Tanzania and collaborative sites in Tanzania, Ghana and Nigeria, is establishing a single patient-consented electronic database with a target of 13,000 SCD patients. In collaboration with the Sickle Cell Support Society of Nigeria, 20 hospitals, with paediatric and adult SCD clinics, are participating in patient recruitment. Demographic and clinical information, collected with uniform case report forms, were entered into Excel spreadsheets and uploaded into Research Electronic Data Capture software by trained data clerks and frequency tables generated. RESULT: Data were available on 3622 patients enrolled in the database, comprising 1889 (52.9%) females and 1434 (39.6%) children ≤15 years. The frequencies of Hb SS, Hb SC and Hb Sß thalassemia in this data set were 97.5%, 2.5% and 0% respectively. Sixty percent, 23.8%, 5.9%, 4.8% and 2.5% have had bone pain crisis, dactylitis, acute chest syndrome, priapism and stroke respectively. The most frequent chronic complications were: leg ulcers (6.5%), avascular necrosis of bone (6.0%), renal (6.3%) and pulmonary hypertension (1.1%). Only 13.2% had been hospitalized while 67.5% had received blood transfusion. CONCLUSION: These data on the spectrum of clinical phenotypes of SCD are useful for planning, improving the management of SCD across Nigeria and provide a foundation for genomic research on SCD.

HemoTypeSC, a low-cost point-of-care testing device for sickle cell disease: Promises and challenges.

BACKGROUND: Sickle cell disease (SCD) is a neglected burden of growing importance. >312,000 births are affected annually by sickle cell anaemia (SCA). Early interventions such as newborn screening, penicillin prophylaxis and hydroxyurea can substantially reduce the mortality and morbidity associated with SCD. Nevertheless, their implementation in African countries has been mostly limited to pilot projects. Recent development of low-cost point-of-care testing (POCT) devices for sickle haemoglobin (HbS) could greatly facilitate the diagnosis of those affected. METHODS: We conducted the first multi-centre, real-world assessment of a low-cost POCT device, HemoTypeSC, in a low-income country. Between September and November 2017, we screened 1121 babies using both HemoTypeSC and HPLC and confirmed discordant samples by molecular diagnosis. FINDINGS: We found that, in optimal field conditions, the sensitivity and specificity of the test for SCA were 93.4% and 99.9%, respectively. All 14 carriers of haemoglobin C were successfully identified. Our study reveals an overall accuracy of 99.1%, but also highlights the importance of rigorous data collection, staff training and accurate confirmatory testing. It suggests that HPLC results might not be as reliable in a resource-poor setting as usually considered. INTERPRETATION: The use of such a POCT device can be scaled up and routinely used across multiple healthcare centres in sub-Saharan Africa, which would offer great potential for the identification and management of vast numbers of individuals affected by SCD who are currently undiagnosed. FUNDING US: Imperial College London's Wellcome Trust Centre for Global Health Research (grant #WMNP P43370).

Preliminary Evaluation of a Point-of-Care Testing Device (SickleSCAN™) in Screening for Sickle Cell Disease.

Sickle cell disease affects about 150,000 births annually in Nigeria. Early diagnosis is hampered by factors such as centralized and urban localization of laboratories, high cost of diagnostic equipment and inadequate skilled manpower to operate them. The need for a low-cost, portable, easy-to-use diagnostic test for sickle cell disease is critical, especially in resource-poor countries. In this study, we evaluated the performance characteristics of a novel point-of-care testing device (SickleSCAN™), and its acceptability and feasibility, as a possible screening tool for sickle cell disease. In the first phase, we assessed the performance characteristics of SickleSCAN™ by evaluating 57 subjects comprising both children and adults attending a primary health center, for Hb SS (ßS/ßS; HBB: c.20A>T), Hb SC (ßS/ßC; HBB: c.19G>A) and Hb AS (ßA/ßS) using SickleSCAN™, cellulose acetate electrophoresis (CAE) and high performance liquid chromatography (HPLC). Performance characteristics such as diagnostic sensitivity and specificity were compared to HPLC as a standard method. We subsequently undertook a second phase wherein the acceptability and feasibility of the device for sickle cell disease screening, was evaluated using semi-structured and structured questionnaires among 197 healthcare personnel and 221 subjects, respectively. Sickle cell disease was carried by 3.4% of the subjects. The diagnostic sensitivity, specificity and test efficiency of SickleSCAN™ for sickle cell disease (Hb SS and Hb SC), were 100.0, 98.2 and 98.2%, respectively. Findings from this study showed SickleSCAN™ to be a viable screening tool that can easily be applied in community-based screening for early diagnosis of sickle cell disease with little expertise and low cost.

Blood pressure indices and disease severity in patients with sickle cell anaemia.

Background: Individuals with sickle cell anaemia (SCA) have lower systemic blood pressures compared to individuals with haemoglobin Hb AA phenotype. Objective: Seventy-nine (79) individuals with SCA (subjects) in steady state and 50 age-matched individuals with Hb AA (controls) were prospectively studied. Height, blood pressure (BP), weight, creatinine clearance (by 24-hour urine collection), full blood count (FBC) and reticulocyte count were obtained from all subjects and controls. Body mass index (BMI), corrected reticulocyte count, mean arterial pressure (MAP) and pulse pressure (PP) were calculated using standard protocols.The frequency of vaso-occlusive crises in the last one year and number of blood transfusions in the last two years were obtained from subjects. Data was analyzed using descriptive and inferential statistics and p ≤0.05 was used to define the level of statistical significance. Methodology: Seventy-nine (79) individuals with SCA (subjects) in steady state and 50 age-matched individuals with Hb AA (controls) were prospectively studied. Height, blood pressure (BP), weight, creatinine clearance (by 24-hour urine collection), full blood count (FBC) and reticulocyte count were obtained from all subjects and controls. Body mass index (BMI), corrected reticulocyte count, mean arterial pressure (MAP) and pulse pressure (PP) were calculated using standard protocols.The frequency of vaso-occlusive crises in the last one year and number of blood transfusions in the last two years were obtained from subjects. Data was analyzed using descriptive and inferential statistics and p ≤0.05 was used to define the level of statistical significance. Results: The systolic (105.52±11.75mmHg and 113.20±7.94mmHg respectively; P = 0.01), diastolic (62.59±9.33mmHg and 75.40±5.70mmHg respectively; P=0.03) and mean arterial pressures (76.90±8.81mmHg and 88.00±5.51mmHg respectively; P =0.04) were significantly lower in subjects when compared with controls. ; pulse pressure (PP) was however significantly higher in subjects than controls (42.92±10.91mmHg and 37.80±7.43mmHg respectively (P = 0.03). In female subjects, the white cell count was negatively correlated with systolic BP (r = -0.39;P = 0.01) and PP (r = -0.33; P = 0.03). Conclusion: Lower systolic and pulse pressures may predict worsening disease severity in individuals with sickle cell anaemia.

Degrees of kidney disease in nigerian adults with sickle-cell disease.

OBJECTIVE: To study degrees of chronic kidney disease (CKD) using creatinine clearance in adult Nigerian patients with sickle-cell disease (SCD). METHODS: One hundred SCD patients, made up of 79 HbSS (homozygous haemoglobin S) patients and 21 HbSC (heterozygous haemoglobins S and C) patients, were investigated prospectively, along with 50 normal controls. Their sociodemographic data, weight and drug history were documented. Each participant underwent dipstick urinalysis, and creatinine clearance was calculated following a 24-hour urine collection and serum creatinine measurement. They were categorized into stages of CKD based on the creatinine clearance. RESULTS: Of the 79 HbSS patients, 14 (18%), 28 (35%), 33 (42%) and 4 (5%) had stage 1, 2, 3 and 4 CKD, respectively. In the HbSC group, 3 (14%), 9 (43%) and 9 (43%) patients had stage 1, 2 and 3 CKD, respectively. Proteinuria was noted in 16 (20%) HbSS patients but not in any of the HbSC patients. Of the subjects aged ≤24 years (n = 49), 9 (18%), 18 (37%), 21 (43%) and 1 (2%) had stage 1, 2, 3 and 4 CKD, respectively. Of those aged >24 years (n = 51), 8 (16%), 19 (37%), 21 (41%) and 3 (6%) had stage 1, 2, 3 and 4 CKD, respectively. None of the subjects had stage 5 CKD. CONCLUSION: In this study, the adult subjects with SCD had various degrees of CKD. Adequate follow-up and active intervention are advocated to delay the onset of end-stage nephropathy.

Strategies to improve healthcare services for patients with sickle cell disease in Nigeria: The perspectives of stakeholders.

Background: Sickle cell disease (SCD) continues to pose physical and psychosocial burdens to patients, caregivers and health workers. Stakeholder engagement in the processes of policy making and implementation is increasingly becoming the cornerstone of best practices in healthcare. Aim and Objectives: To engage stakeholders with a view to assessing the knowledge of SCD; ascertain the challenges associated with accessibility and affordability of healthcare services; improve the quality of care, and thereby effect behavioral change through increasing attendance and follow-up of patients in the clinics. Methodology: A Stakeholders' Engagement meeting organized by the Sickle Pan Africa Research Consortium Nigeria Network (SPARC-NEt) was attended by patients, caregivers and members of patient support groups, healthcare providers and management/policymakers. The engagement was through PowerPoint presentations, structured questionnaires and an interactive session. The structured questionnaire assessed the knowledge of stakeholders about SCD; the quality of healthcare services; challenges with access and affordability; and SCD-related government policies. Results: Three hundred and twelve stakeholders attended the engagement meeting. Of the 133 that participated in the study, medical workers were the most represented. The majority had good knowledge of what causes SCD (96.2%) and the best place to get help during SCD crisis (98.5%). However, knowledge of the specific preventive measures of SCD and its crisis was not optimal. In terms of the role of community engagement and education, only about one-quarter of the study participants, 34 (25.6%) knew about their positive role in reducing the prevalence of SCD and alleviating SCD crises. Challenges identified include inadequate healthcare personnel and facilities, delay in obtaining laboratory results, long waiting time in the clinic, poor communication, absence of holistic consultation, uncoordinated healthcare services, high cost of care, ignorance, non-prioritization of SCD by government, lack of multisectoral collaboration and partnership with NGOs and international organizations. Strategies proffered to improve healthcare services include, community/stakeholder engagement and health education, sickle cell daycare services, access to a willing and dedicated multidisciplinary workforce, collaboration with support groups and government policies and programs. Conclusion: There is need for regular stakeholder engagement to improve access to healthcare services for SCD patients in Nigeria.

Reconfigurable terahertz metasurfaces coherently controlled by wavelength-scale-structured light.

Structuring light-matter interaction at a deeply subwavelength scale is fundamental to optical metamaterials and metasurfaces. Conventionally, the operation of a metasurface is determined by the collective electric polarization response of its lithographically defined structures. The inseparability of electric polarization and current density provides the opportunity to construct metasurfaces from current elements instead of nanostructures. Here, we realize metasurfaces using structured light rather than structured materials. Using coherent control, we transfer structure from light to transient currents in a semiconductor, which act as a source for terahertz radiation. A spatial light modulator is used to control the spatial structure of the currents and the resulting terahertz radiation with a resolution of 5.6 ± 0.8 µm , or approximately λ / 54 at a frequency of 1 THz. The independence of the currents from any predefined structures and the maturity of spatial light modulator technology enable this metasurface to be reconfigured with unprecedented flexibility.

Determinants of hydroxyurea use among doctors, nurses and sickle cell disease patients in Nigeria.

BACKGROUND: Hydroxyurea (HU) is an evidence-based therapy that is currently the most effective drug for sickle cell disease (SCD). HU is widely used in high-income countries with consequent reduction of morbidity and mortality. In Nigeria, HU is prescribed by physicians while nurses are mainly involved in counseling the patients to ensure adherence. The extent of utilization and the determinant factors have not been sufficiently evaluated in Nigeria. OBJECTIVE: To assess the frequency of use of HU and factors affecting utilization among healthcare providers, patients, and caregivers for SCD. METHODS: A questionnaire was administered online and in- person to assess the frequency of HU use and the factors that promote and limit its use. The data were analyzed by descriptive statistics using IBM SPSS software version 23 and the result was presented in frequency tables and percentages. RESULT: A total of 137 physicians, 137 nurses, and 237 patients/caregivers responded to the survey. The rate of prescription of HU by doctors in the past 6 months was 64 (46.7%), 43 (31.4%) nurses provided counseling and 36 (15.6%) patients were on HU. Among doctors, adequate knowledge (91.3%), clinical benefits and safety (94.8%), and inclusion of HU in management guidelines (86.9%) were motivators for prescribing it while inadequate knowledge (60.9%) and unawareness of treatment guidelines (68.6%) constituted barriers. Among nurses, reduction of crisis (91.6%) and safety (64.8%) were the major motivators while barriers were high cost (79.1%) and intensive monitoring (63.1%) of HU treatment. Among the patients, the major motivator was the reduction of crises (80.3%) while poor knowledge (93.2%), high cost of the drug (92.2%) while monitoring (91.2%), non-availability (87.7%) and side effects (83.9%) were the major barriers for the utilization of HU. CONCLUSION: HU prescription and utilization are still poor among healthcare providers and patients. Inadequate knowledge, non-availability and high cost of HU as well as unawareness of treatment guidelines constitute major barriers to prescription and utilization.

MYH9 and APOL1 are both associated with sickle cell disease nephropathy.

Renal failure occurs in 5-18% of sickle cell disease (SCD) patients and is associated with early mortality. At-risk SCD patients cannot be identified prior to the appearance of proteinuria and the pathobiology is not well understood. The myosin, heavy chain 9, non-muscle (MYH9) and apolipoprotein L1 (APOL1) genes have been associated with risk for focal segmental glomerulosclerosis and end-stage renal disease in African Americans. We genotyped 26 single nucleotide polymorphisms (SNPs) in MYH9 and 2 SNPs in APOL1 (representing the G1 and G2 tags) in 521 unrelated adult (18-83 years) SCD patients screened for proteinuria. Using logistic regression, SNPs were evaluated for association with proteinuria. Seven SNPs in MYH9 and one in APOL1 remained significantly associated with proteinuria after multiple testing correction (P < 0·0025). An MYH9 risk haplotype (P = 0·001) and the APOL1 G1/G2 recessive model (P < 0·0001) were strongly associated with proteinuria, even when accounting for the other. Glomerular filtration rate was negatively correlated with proteinuria (P < 0·0001), and was significantly predicted by an interaction between MYH9 and APOL1 in age-adjusted analyses. Our data provide insight into the pathobiology of renal dysfunction in SCD, suggesting that MYH9 and APOL1 are both associated with risk.

Barriers to Therapeutic Use of Hydroxyurea for Sickle Cell Disease in Nigeria: A Cross-Sectional Survey.

Background: Sickle cell disease, the inherited blood disorder characterized by anemia, severe pain and other vaso-occlusive complications, acute chest syndrome, disproportionate hospitalization, and early mortality, has significant financial, social, and psychosocial impacts and drains individuals, families, and health systems globally. Hydroxyurea could improve the health of the 300,000 individuals born each year with sickle cell disease in sub-Saharan Africa; however, challenges to adoption and adherence persist. This study assessed the barriers to therapeutic use of hydroxyurea for sickle cell disease within the Nigerian healthcare system, specifically from the level of the patient, provider, and health system. Methods: We used purposive sampling to recruit participants from 13 regions in Nigeria. A cross-sectional survey was administered to physicians (n = 70), nurses or counselors (n = 17), and patients or their caregivers (n = 33) at 13 health centers. Findings were mapped onto the appropriate Consolidated Framework for Implementation Research (CFIR) domains. Results: This study was able to identify factors that mapped onto the inner setting, outer setting, and characteristics of individuals domains of CFIR. The majority of physicians (74.3%) prescribe hydroxyurea, and half stated hydroxyurea is the standard of care. Among clinicians, barriers included limited knowledge of the drug, as well as low self-efficacy to prescribe among physicians and to counsel among nurses; perceived side effects; perceived patient preference for traditional medicine; cost for patient and expense of accompanying laboratory monitoring; and limited availability of the drug and equipment for laboratory monitoring. Among patients and caregivers, barriers included lack of knowledge; perceived side effects; cost; religious beliefs of disease causation; and lack of pediatric formulation. Conclusions: Findings suggest that patient, provider, and health systems-level interventions are needed to improve hydroxyurea uptake among providers and adherence among patients with sickle cell disease in Nigeria. Interventions such as patient education, provider training, and policy change could address the disproportionate burden of sickle cell disease in sub-Saharan Africa and thus improve health equity.

A Multi-centre Survey of Acceptability of Newborn Screening for Sickle Cell Disease in Nigeria.

Background Sickle cell disease (SCD) is a major genetic disease that manifests early in life and may lead to significant morbidities. One of the health care services that have been effective in reducing the burden of SCD in developed countries is newborn screening (NBS) followed by pneumococcal vaccines, penicillin prophylaxis, and hydroxyurea treatment. Yet, in sub-Saharan African countries, where about 75% of annual affected babies worldwide are born, NBS programmes are largely unavailable. It is not clear whether this is due to technical challenges associated with setting up such programmes, or significant cultural and social barriers to its acceptance in such settings. Objective Our aim was to ascertain the attitudes to and acceptability of NBS in Nigeria among various socio-demographic groups including health professionals, undergraduate students, parents of children with SCD and SCD patients. Methods Data on socio-demographic characteristics, knowledge of SCD and attitude towards NBS were collected using a semi-structured pre-tested questionnaire from April to July 2014 across 15 health institutions and university campuses in Nigeria. Data were collected from 1,301 respondents across Nigeria. Results There was good knowledge of SCD as an inherited blood disorder. Although 86% of respondents (n = 1,119) supported NBS, there was a statistically significant relationship between support for NBS and age (p = 003), educational status (p = 000) and religion (p = 000). Conclusion This study suggests that there is a good acceptability of NBS across Nigeria. The main barriers to its use are likely to be financial and practical, rather than social or cultural.