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Background: An understanding of the genetic mechanisms underlying diseases in ancestrally diverse populations is an important step towards development of targeted treatments. Research in African and African admixed populations can enable mapping of complex traits, because of their genetic diversity, extensive population substructure, and distinct linkage disequilibrium patterns. We aimed to do a comprehensive genome-wide assessment in African and African admixed individuals to better understand the genetic architecture of Parkinson's disease in these underserved populations., Methods: We performed a genome-wide association study (GWAS) in people of African and African admixed ancestry with and without Parkinson's disease. Individuals were included from several cohorts that were available as a part of the Global Parkinson's Genetics Program, the International Parkinson's Disease Genomics Consortium Africa, and 23andMe. A diagnosis of Parkinson's disease was confirmed clinically by a movement disorder specialist for every individual in each cohort, except for 23andMe, in which it was self-reported based on clinical diagnosis. We characterised ancestry-specific risk, differential haplotype structure and admixture, coding and structural genetic variation, and enzymatic activity., Findings: We included 197 918 individuals (1488 cases and 196 430 controls) in our genome-wide analysis. We identified a novel common risk factor for Parkinson's disease (overall meta-analysis odds ratio for risk of Parkinson's disease 1·58 [95% CI 1·37-1·80], p=2·397 × 10 -14 ) and age at onset at the GBA1 locus, rs3115534-G (age at onset β=-2·00 [SE=0·57], p=0·0005, for African ancestry; and β=-4·15 [0·58], p=0·015, for African admixed ancestry), which was rare in non-African or non-African admixed populations. Downstream short-read and long-read whole-genome sequencing analyses did not reveal any coding or structural variant underlying the GWAS signal. The identified signal seems to be associated with decreased glucocerebrosidase activity., Interpretation: Our study identified a novel genetic risk factor in GBA1 in people of African ancestry, which has not been seen in European populations, and it could be a major mechanistic basis of Parkinson's disease in African populations. This population-specific variant exerts substantial risk on Parkinson's disease as compared with common variation identified through GWAS and it was found to be present in 39% of the cases assessed in this study. This finding highlights the importance of understanding ancestry-specific genetic risk in complex diseases, a particularly crucial point as the Parkinson's disease field moves towards targeted treatments in clinical trials. The distinctive genetics of African populations highlights the need for equitable inclusion of ancestrally diverse groups in future trials, which will be a valuable step towards gaining insights into novel genetic determinants underlying the causes of Parkinson's disease. This finding opens new avenues towards RNA-based and other therapeutic strategies aimed at reducing lifetime risk of Parkinson's disease., Funding: The Global Parkinson's Genetics Program, which is funded by the Aligning Science Across Parkinson's initiative, and The Michael J Fox Foundation for Parkinson's Research., Competing Interests: Declaration of interests DV, HI, HLL, KSL, CXA, and MAN's participation in this project was part of a competitive contract awarded to Data Tecnica International by the US National Institutes of Health (NIH) to support open science research. MAN also currently serves on the scientific advisory board for Character Biosciences and Neuron 23. KH is employed by 23andMe and holds stock or stock options in 23andMe. AS, MBM, PAJ, CB, KD, MJK, JJK, and PWC are employed by the NIH. AS also declares funding for the present work from the Michael J Fox Foundation (MJFF) and Aligning Science Across Parkinson's (ASAP); royalties for a diagnostic for stroke (unrelated to the current work); honoraria for associate editorial work for the journals Movement Disorders and npj Parkinson's Disease; and travel support from the Chan Zuckerberg Initiative to attend annual investigators’ meeting, MJFF to attend Parkinson's Progression Marker Initiative annual meeting, and Weill Cornell to give grand rounds. The spouse of AS is an employee of GeneDx. OOk, IE, HI, JHK, and DV declare funding from the NIH (1ZIA AG000534-04). HI also declares honoraria from GP2 for a steering committee meeting and from MJFF for a data community meeting. DGS declares support for the present work from ASAP (for the BLAAC-PD study); research support from the NIH (P50 108675), the MJFF, the Parkinson Foundation of the National Capital Area, the American Parkinson Disease Association, AbbVie, and Genentech; book royalties from McGraw Hill; consulting fees from AbbVie, Curium Pharma, F Hoffman-La Roche, Appello Pharma, and Blue Rock Therapeutics; participation on a data safety monitoring board or advisory board for Sanofi-Aventis, Theravance, and Alnylam Pharmaceuticals; being Deputy Editor of the journal Movement Disorders; and being Chair of the Scientific Advisory Board of the American Parkinson Disease Association. DAH declares support for the present work from the NIH, the MJFF, the CHDI Foundation, Parkinson's Foundation, Lundbeck, Uniqure, and Neurocrine. TX declares research funding from the MJFF, the American Parkinson's Disease Association, and the NIH; and consulting fees from Parkinson's Foundation and CVS Caremark. HH and JH declare research funding by the Medical Research Council (UK), the Wellcome Trust, the MSA Trust, NIHR University College London Hospitals Biomedical Research Centre (NIHR-BRC), the MJFF, the Fidelity Trust, the Rosetrees Trust, the Guarantors of Brain, SOLVE-RD, and the Dolby Family Fund. HRM declares support from the MJFF related to this work; grants not related to this work from PSP Association, CBD Solutions, Drake Foundation, and Cure Parkinson's Trust; consulting fees from Roche, Amylyx, and Aprinoia; speaker's honoraria from Kyowa-Kirin, the British Medical Journal, and the Movement Disorders Society; travel support from the MJFF and the Movement Disorders Society; and being on the advisory board for Cure PSP Association, the Association of British Neurologists Movement Disorders special interest group, and the Association of British Neurologists Neurogenetics advisory group. HRM is a co-applicant on a patent application related to C9ORF72—Method for diagnosing a neurodegenerative disease (PCT/GB2012/052140). ES declares funding for the present work from the US National Human Genome Research Institute (NHGRI) Intramural Research Program; grants from ASAP and MJFF; and a cooperative research and development agreement with Roche. EAS declares funding for the present work from the MJFF; and travel support from the MJFF. MND declares funding for the present work from MJFF; grant support from ASAP; speaker's honoraria from the Parkinson's Foundation; and is a member of the Parkinson's Foundation Gulf Coast advisory board. Z-HF declares salary support from the MJFF. OOOj declares a study grant from the NIHR; honoraria for educational courses from the International Parkinson and Movement Disorder Society (IPMDS); travel support from P2 for an annual investigators’ meeting and from the IPMDS for congress attendance; and is a member of the executive committee of the IPMDS. NUO declares a study grant from the NIHR; travel support and honoraria for educational courses from the IPMDS; and being Chair of the IPMDS Africa Section. UA declares a study grant from the NIHR. RA declares grant support from the NIH (U01HG010273, U19AG074865), the UK Royal Society and the African Academy of Sciences Future Leaders—African Independent Research (FLR/R1/191813, FCG/R1/201034), and the Global Brain Health Institute, Alzheimer's Association, and Alzheimer's Society UK (GBHI ALZ UK-21- 24204). TF declares speaker's honoraria from Roche; travel support from the Alzheimer's Association; and is a member of the Alzheimer's Disease International medical and scientific advisory panel. CB declares support from ASAP. KD declares a Japan Society for the Promotion of Science Research Fellowship. JJK declares participation in the graduate school programme for Queen Mary University London (London, UK). PAJ declares participation in the graduate school programme for University College London (London, UK). MBM declares participation in a summer internship at Genentech/Roche (unrelated to the current work). All other authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Introduction: The association between MAPT and PD risk may be subject to ethnic variability even within populations of similar geographical origin. Data on MAPT haplotype frequencies, and its association with PD risk in black Africans are lacking. We aimed to determine the frequencies of MAPT haplotypes and their role as risk factors for PD and age at onset in Nigerians., Methods: The haplotype and genotype frequencies of MAPT rs1052553 were analysed in 907 individuals with PD and 1022 age-matched healthy controls from the Nigeria Parkinson's Disease Research network cohort. Clinical data related to PD included age at study, age at onset (AAO), and disease duration., Results: The frequency of the H1 haplotype was 98.7% in PD, and 99.1% in controls (p = 0.19). The H2 haplotype was present in - 1.3% of PD and 0.9% of controls (p = 0.24). The most frequent MAPT genotype was H1H1 (PD - 97.5%, controls - 98.2%). The H1 haplotype was not associated with PD risk after accounting for gender and AAO (Odds ratio for H1/H1 vs H1/H2 and H2/H2: 0.68 (95% CI:0.39-1.28); p = 0.23)., Conclusions: Our findings support previous studies that report a low frequency of the MAPT H2 haplotype in black ancestry Africans but document its occurrence in Nigerians. The MAPT H1 haplotype was not associated with an increased risk or age at onset of PD in this cohort., Competing Interests: Declaration of competing interest R.A. is supported by the following grants: US NIH/NHGRI (U01HG010273) and the UK Royal Society/African Academy of Sciences (FLR/R1/191813). M.R. received funding from the University College London Grand challenges Small Grants (Award ID:177813 and the Michael J Fox Foundation Genetic Diversity in Parkinson's Disease 2019 (Grant ID:17483). H.H. is supported by the Michael J Fox Foundation Genetic Diversity in Parkinson's Disease (Grant ID: 17483). N.U.O. is supported by the Michael J Fox Foundation Genetic Diversity in Parkinson's Disease 2019 (Grant ID:17483) and the TETFund National Research Fund (NRF) 2019. S.B.-C., C.B. and A.S. are supported by the Intramural Research Program, National Institute on Aging, National Institutes of Health and US Department of Health and Human Services project ZO1 AG000949 and all these authors declare no non-financial competing interests. The remaining authors declare no competing interests., (Copyright © 2023. Published by Elsevier Ltd.)

The relationship between APOE polymorphisms and Parkinson's disease (PD) in black Africans has not been previously investigated. We evaluated the association between APOE polymorphic variability and self-declared cognition in 1100 Nigerians with PD and 1097 age-matched healthy controls. Cognition in PD was assessed using the single item cognition question (item 1.1) of the MDS-UPDRS. APOE genotype and allele frequencies did not differ between PD and controls (p > 0.05). No allelic or genotypic association was observed between APOE and age at onset of PD. In PD, APOE ε4/ε4 conferred a two-fold risk of cognitive impairment compared to one or no ε4 (HR: 2.09 (95% CI: 1.13-3.89; p = 0.02)), while APOE ε2 was associated with modest protection against cognitive impairment (HR: 0.41 (95% CI 0.19-0.99, p = 0.02)). Of 773 PD with motor phenotype and APOE characterized, tremor-dominant (TD) phenotype predominated significantly in ε2 carriers (87/135, 64.4%) compared to 22.2% in persons with postural instability/gait difficulty (PIGD) (30/135) and 13.3% in indeterminate (ID) (18/135, 13.3%) (p = 0.037). Although the frequency of the TD phenotype was highest in homozygous ε2 carriers (85.7%), the distribution of motor phenotypes across the six genotypes did not differ significantly (p = 0.18). Altogether, our findings support previous studies in other ethnicities, implying a role for APOE ε4 and ε2 as risk and protective factors, respectively, for cognitive impairment in PD., (© 2022. The Author(s).)

Background: Human genetics research lacks diversity; over 80% of genome-wide association studies have been conducted on individuals of European ancestry. In addition to limiting insights regarding disease mechanisms, disproportionate representation can create disparities preventing equitable implementation of personalized medicine., Objective: This systematic review provides an overview of research involving Parkinson's disease (PD) genetics in underrepresented populations (URP) and sets a baseline to measure the future impact of current efforts in those populations., Methods: We searched PubMed and EMBASE until October 2021 using search strings for "PD," "genetics," the main "URP," and and the countries in Latin America, Caribbean, Africa, Asia, and Oceania (excluding Australia and New Zealand). Inclusion criteria were original studies, written in English, reporting genetic results on PD from non-European populations. Two levels of independent reviewers identified and extracted information., Results: We observed imbalances in PD genetic studies among URPs. Asian participants from Greater China were described in the majority of the articles published (57%), but other populations were less well studied; for example, Blacks were represented in just 4.0% of the publications. Also, although idiopathic PD was more studied than monogenic forms of the disease, most studies analyzed a limited number of genetic variants. We identified just nine studies using a genome-wide approach published up to 2021, including URPs., Conclusion: This review provides insight into the significant lack of population diversity in PD research highlighting the immediate need for better representation. The Global Parkinson's Genetics Program (GP2) and similar initiatives aim to impact research in URPs, and the early metrics presented here can be used to measure progress in the field of PD genetics in the future. © 2022 International Parkinson and Movement Disorder Society., (© 2022 International Parkinson and Movement Disorder Society.)

Parkinson's disease (PD) has the fastest rising prevalence of all neurodegenerative diseases worldwide. However, it is unclear whether its incidence has increased after accounting for age and changes in diagnostic patterns in the same population. We conducted a cohort study in individuals aged ≥50 years within a large UK primary care database between January 2006 and December 2016. To account for possible changes in diagnostic patterns, we calculated the incidence of PD using four case definitions with different stringency derived from the combination of PD diagnosis, symptoms, and treatment. Using the broadest case definition, the incidence rate (IR) per 100,000 person years at risk (PYAR) was 149 (95% CI 143.3-155.4) in 2006 and 144 (95% CI 136.9-150.7) in 2016. In conclusion, the incidence of PD in the UK remained stable between 2006 and 2016, when accounting for age and diagnostic patterns, suggesting no major change in underlying risk factors for PD during this time period in the UK., (© 2022. The Author(s).)

Background: Hospitalization in Parkinson's disease (PD) is associated with reduced quality of life, caregiver burden and high costs. However, no large-scale studies of rate and causes of hospitalizations in patients with PD have been published., Objective: To investigate the rate and reasons for hospitalization and factors associated with hospitalization among people with PD compared to the general population., Methods: We examined rate and causes of admission in PD patients and matched controls in The Health Improvement Network from 2006 to 2016. Multivariable Poisson regression was used to explore the effects of age, gender, social deprivation, urbanicity and practice geographic location on hospitalization., Results: In the longitudinal data from 9,998 newly diagnosed individuals with PD and 55,554 controls without PD aged ≥50 years, 39% of PD patients and 28% of controls were hospitalised over a median follow-up of 5.1 years. The adjusted incidence rate ratio (IRR) of hospitalization in PD compared to controls was 1.33 (95% CI:1.29-1.37) and rose with increased follow-up duration. Hospitalization rate was overall higher in the older age groups, but the adjusted IRR of hospitalization compared to controls was highest in the youngest age group. PD patients were more often admitted with falls/fractures, infections, gastrointestinal complications, PD, dementia, psychosis/hallucinations, postural hypotension, electrolyte disturbances, stroke and surgical procedures and slightly less often due to hypertension., Conclusion: People with PD have an increased hospitalization rate compared to controls, particularly in the younger age groups, and it increases with longer disease duration. The complications of motor and non-motor features of PD are amongst the main reasons for admission, some of which could be managed preventatively to avoid admissions.

Background: Parkinson's disease (PD) is associated with increased mortality, but little is known about changes over time, and relationship to disease progression., Objectives: To explore how PD mortality rates have changed over time and their relationship to disease duration and demographics using a large population-based cohort in the UK., Methods: We included individuals aged 50+ years with a first recording of PD diagnosis and at least two prescriptions of any antiparkinsonian drug actively registered within a general practice from 2006 to 2016 and up to six frequency-matched controls from The Health Improvement Network (THIN) database. We estimated adjusted mortality rates using multivariable Poisson regression., Results: A total of 10,104 people with a diagnosis of PD and 55,664 people without PD were included. Overall, PD was associated with slightly increased mortality compared to non-PD controls (adjusted mortality rate ratio: 1.14; 95% CI: 1.03 to 1.19). Adjusted mortality rates per 1000 person-years at risk for people with PD approximately doubled in the 5 years following diagnosis from 43 (95% CI: 38 to 48) to 75 (95% CI: 64 to 85). Following adjustments for age, gender, and time since diagnosis, mortality rates between 2007 and 2016 declined more slowly for people with PD (2% per year; 95% CI: 0%-4%) compared to people without PD (5% per year; 95% CI: 3%-6%)., Conclusions: Whilst mortality in PD is only slightly increased overall, it gradually increases with advancing disease. There has been a decline in mortality in PD over time, but this decrease was less pronounced than that in the general population. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society., (© 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.)

Background: We determined the prevalence, incidence, and risk factors for epilepsy in Nigeria., Methods: We conducted a door-to-door survey to identify cases of epilepsy in 3 regions. We estimated age-standardized prevalence adjusted for nonresponse and sensitivity and the 1-year retrospective incidence for active epilepsy. To assess potential risk factors, we conducted a case-control study by collecting sociodemographic and risk factor data. We estimated odds ratios using logistic regression analysis and corresponding population attributable fractions (PAFs)., Results: We screened 42,427 persons (age ≥6 years), of whom 254 had confirmed active epilepsy. The pooled prevalence of active epilepsy per 1,000 was 9.8 (95% confidence interval [CI] 8.6-11.1), 17.7 (14.2-20.6) in Gwandu, 4.8 (3.4-6.6) in Afikpo, and 3.3 (2.0-5.1) in Ijebu-Jesa. The pooled incidence per 100,000 was 101.3 (95% CI 57.9-167.6), 201.2 (105.0-358.9) in Gwandu, 27.6 (3.3-128.0) in Afikpo, and 23.9 (3.2-157.0) in Ijebu-Jesa. Children's significant risk factors included febrile seizures, meningitis, poor perinatal care, open defecation, measles, and family history in first-degree relatives. In adults, head injury, poor perinatal care, febrile seizures, family history in second-degree relatives, and consanguinity were significant. Gwandu had more significant risk factors. The PAF for the important factors in children was 74.0% (71.0%-76.0%) and in adults was 79.0% (75.0%-81.0%)., Conclusion: This work suggests varied epidemiologic numbers, which may be explained by differences in risk factors and population structure in the different regions. These variations should differentially determine and drive prevention and health care responses., (© 2021 American Academy of Neurology.)

Introduction: Parkinson's disease (PD) is associated with an increased risk of admission to hospital; however data on the main reasons for admission are lacking. Our objective was to determine the pooled prevalence of the most common factors leading to admission among people with Parkinson's disease., Methodology: A systematic literature search was conducted in 11 electronic databases. We included all studies providing reasons for admissions among PD patients without restrictions to diagnostic criteria of PD, language or year of study. In the included studies, methodological quality, publication bias and heterogeneity were assessed. Meta-analysis was performed using random-effects models to calculate the pooled estimates of the identified top factors that lead to admission among people with PD., Results: A total of 7283 studies were identified of which nine studies including 7162 people with PD were included in this review. There was a high degree of heterogeneity between studies regarding reasons for hospitalisation. The pooled prevalence of the topmost reasons for hospitalisation among people with PD was 22% (95%CI 16.0%–30.0%) for infections (mainly urinary tract infections and pneumonia); 19% (95%CI 13.0%–27.0%) for worsening motor manifestations of PD; 18% (95%CI 14.0%–21.0%) for falls/fractures; 13% (95%CI 9.0%–18%) for cardiovascular co-morbidities; 8% (95%CI 4.0%–13.0%) for neuropsychiatric and 7% (95%CI 4.0%–11.0%) for gastrointestinal complications., Conclusion: The main reasons for hospitalisation among people with PD are infections, worsening motor features, falls/fractures, cardiovascular co-morbidities, neuropsychiatric and gastrointestinal complications. Further research is needed on targeting and implementing preventative strategies., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: High red blood cell distribution width (RDW) is related to impairment of erythropoiesis, reflecting chronic inflammation and increased levels of oxidative stress, both of which are telltale signs of type 2 diabetics. The aim of this study was to evaluate the relationship between the RDW and fasting blood sugar/blood pressure, and compare the results from diabetics with nondiabetic controls., Methods: This was an unmatched case-control study involving 200 participants consisting of 100 diabetics and 100 nondiabetic controls. Blood (4.5 mL) was collected from all of the diabetics and nondiabetic controls, and placed into EDTA anticoagulant tubes. A full blood count was performed using the Sysmex KX-21N, a three-part auto analyzer able to run 19 parameters per sample, including RDW. Blood pressure was measured during sample collection and in a sitting position., Results: The mean fasting blood sugar level was 95.20±30.10 mg/dL in the controls, and 147.85±72.54 mg/dL in the diabetics. The mean blood pressures for diabetics was 138/90 mmHg and for non-diabetics 120/80 mmHg. The mean RDW-SD (RDW standard deviation) was 46.44±4.64 fl in the controls, and 46.84±3.18 in the diabetics. The mean RDW-CV (RDW coefficient of variation) was 14.74%±1.94% in controls, and 14.80±0.71 for diabetics. No statistically significant correlation was found between the RDW-SD and fasting blood sugar/blood pressure in the diabetics. A statistically significant positive correlation was found between the RDW-CV and blood pressure in the diabetics., Conclusion: A positive correlation between the RDW-CV and blood pressure was established in the diabetics in this study.

Background: There is a significant association of human T-lymphotropic viruses (HTLV) with lymphoid malignancies. HTLV causes a lymphoproliferative malignancy of CD4-activated cells called adult T-cell leukemia/lymphoma (ATL) and a chronic myelopathy called tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). This study aims to determine the prevalence of HTLV among patients with lymphoid malignancies at a tertiary center in Lagos., Methods: A cross-sectional study was carried out at the hematology clinic of the Lagos State University Teaching Hospital. After obtaining consent, approximately 5 mL of venous blood was collected from each subject. The serum was separated and stored at -20°C. Sera were assayed for HTLV by an enzyme-linked immunoassay (ELISA) for the determination of antibodies to HTLV-1 and -2. Western blot confirmatory testing was done on reactive samples. All patients were also screened for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg) and hepatitis C virus (HCV) by rapid kits., Results: A total of 39 patients with lymphoid malignancies were enrolled, consisting of 24 (61.5%) with solid malignancies, while 15 (38.5%) had leukemia. Only two patients (5.1%) with lymphoid malignancies were reactive on the ELISA test. On confirmatory testing with Western blot, two patients (5.1%) with lymphoid malignancies were also positive for HTLV. All patients were HIV negative, but four were positive to HBsAg and HCV. There was no association between history of previous blood transfusion and positivity to HTLV (P=0.544)., Conclusion: A prevalence of 5.1% of HTLV among patients with lymphoid malignancies was found in this study, and previous history of blood transfusion was not found to be a significant cause of HTLV infection.

Introduction: Transmission of human T-lymphotropic viruses (HTLV) occurs from mother to child, by sexual contact and blood transfusion. Presently, in most centres in Nigeria, there is no routine pre-transfusion screening for HTLV. The study aims to determine the prevalence of HTLV-1 and HTLV-2 among healthy blood donors at a tertiary centre in Lagos., Methods: A cross-sectional study was carried out at the blood donor clinic of the Lagos State University Teaching Hospital (LASUTH), Ikeja. About 5 mls of venous blood was collected from each subject into a sterile plain bottle after obtaining subject's consent. The serum separated and stored at -200C. Sera were assayed for HTLV by an enzyme-linked immunoassay (ELISA) for the determination of antibodies to HTLV 1 and HTLV -2. Western blot confirmatory testing was done on reactive samples. All donors were also screened for HIV, HBsAg and HCV by rapid kits., Results: The seroprevalence of HTLV -1 by ELISA was 1.0% and 0.5% by Western Blot among blood donors. A total of 210 healthy blood donors were enrolled. Only 2 (1.0%) blood donors were repeatedly reactive with ELISA test. On confirmatory testing with Western Blot, 1 (0.5%) blood donor was positive for HTLV. All the healthy blood donors were negative for HIV, HbsAg and HCV. None of the 210 blood donors had been previously transfused; as such no association could be established between transfusion history and HTLV positivity among the blood donors., Conclusion: The seroprevalence of HTLV in this environment is low among healthy blood donors.

The Kikuchi-Fujimoto is a rare, self-limiting disease, which is characterized by regional lymphadenopathy. It occurs worldwide with a higher prevalence among Asians and women below the age of forty years. We present 41-year-old Nigerian woman who was investigated extensively for unilateral left cervical lymphadenopathy. She was eventually diagnosed as having the Kikuchi-Fujimoto disease and was managed conservatively thereafter. We describe a case report and review of literature for better awareness of the disease amongst medical practitioners and pathologists in Africa.