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. Children9s 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.

To evaluate the risk of obstructive sleep apnea (OSA) in a primary care population of elderly Nigerians and to determine its correlates. Clinical and demographic data of 414 elderly individuals in a primary care clinic were obtained. Their risk of OSA was estimated using Berlin questionnaire while Epworth sleepiness scale and the Center for Epidemiologic Studies Depression Scale (CESD-10) were also administered. Of the 414 subjects, 96 (23.2%) met the criteria for a high risk for OSA with a male to female ratio of 1:1. Subjects at high OSA risk (high OSA risk group) were younger than those at low OSA risk (low OSA risk group) (71.4±6.8 vs 73.6±7.7, p=0.011). Mean body mass index (BMI, kg/m(2)) (27.3±5.8 vs 24.7±5.1, p<0.001) and waist circumference (WC, cm) (90.7±13.1 vs 86.5±13.9, p=0.011) were higher in the high OSA risk group compared with the low OSA risk group. A total of 215 (51.9%) and 62 (15.0%) subjects had clinically significant depressive symptoms (CESD-10 score≥10) and excessive daytime sleepiness (EDS), respectively. On regression, the odds of EDS, depressive symptoms, increased BMI and younger age were significantly higher in the high OSA risk group compared with the low OSA risk group. High risk for OSA and depressive symptoms are common in our sample of elderly Nigerians. Depressive symptoms, EDS, BMI and age independently predict high OSA risk in the elderly.

Summary: Background: Understanding the genetic mechanisms underlying diseases in ancestrally diverse populations is a critical step towards the realization of the global application of precision medicine. The African and African admixed populations enable mapping of complex traits given their greater levels of genetic diversity, extensive population substructure, and distinct linkage disequilibrium patterns. Methods: Here we perform a comprehensive genome-wide assessment of Parkinson’s disease (PD) in 197,918 individuals (1,488 cases; 196,430 controls) of African and African admixed ancestry, characterizing population-specific risk, differential haplotype structure and admixture, coding and structural genetic variation and polygenic risk profiling. Findings: We identified a novel common risk factor for PD and age at onset at the GBA1 locus (risk, rs3115534-G; OR=1.58, 95% CI = 1.37 - 1.80, P=2.397E-14; age at onset, BETA =-2.004, SE =0.57, P = 0.0005), that was found to be rare in non-African/African admixed populations. Downstream short- and long-read whole genome sequencing analyses did not reveal any coding or structural variant underlying the GWAS signal. However, we identified that this signal mediates PD risk via expression quantitative trait locus (eQTL) mechanisms. While previously identified GBA1 associated disease risk variants are coding mutations, here we suggest a novel functional mechanism consistent with a trend in decreasing glucocerebrosidase activity levels. Given the high population frequency of the underlying signal and the phenotypic characteristics of the homozygous carriers, we hypothesize that this variant may not cause Gaucher disease. Additionally, the prevalence of Gaucher’s disease in Africa is low. Interpretation: The present study identifies a novel African-ancestry genetic risk factor in GBA1 as a major mechanistic basis of PD in the African and African admixed populations. This striking result contrasts to previous work in Northern European populations, both in terms of mechanism and attributable risk. This finding highlights the importance of understanding population-specific genetic risk in complex diseases, a particularly crucial point as the field moves toward precision medicine in PD clinical trials and while recognizing the need for equitable inclusion of ancestrally diverse groups in such trials. Given the distinctive genetics of these underrepresented populations, their inclusion represents a valuable step towards insights into novel genetic determinants underlying PD etiology. This opens new avenues towards RNA-based and other therapeutic strategies aimed at reducing lifetime risk. Research in Context: Evidence Before this Study: Our current understanding of Parkinson’s disease (PD) is disproportionately based on studying populations of European ancestry, leading to a significant gap in our knowledge about the genetics, clinical characteristics, and pathophysiology in underrepresented populations. This is particularly notable in individuals of African and African admixed ancestries. Over the last two decades, we have witnessed a revolution in the research area of complex genetic diseases. In the PD field, large-scale genome-wide association studies in the European, Asian, and Latin American populations have identified multiple risk loci associated with disease. These include 78 loci and 90 independent signals associated with PD risk in the European population, nine replicated loci and two novel population-specific signals in the Asian population, and a total of 11 novel loci recently nominated through multi-ancestry GWAS efforts. Nevertheless, the African and African admixed populations remain completely unexplored in the context of PD genetics. Added Value of this Study: To address the lack of diversity in our research field, this study aimed to conduct the first genome-wide assessment of PD genetics in the African and African admixed populations. Here, we identified a genetic risk factor linked to PD etiology, dissected African-specific differences in risk and age at onset, characterized known genetic risk factors, and highlighted the utility of the African and African admixed risk haplotype substructure for future fine-mapping efforts. We identified a novel disease mechanism via expression changes consistent with decreased GBA1 activity levels. Future large scale single cell expression studies should investigate the neuronal populations in which expression differences are most prominent. This novel mechanism may hold promise for future efficient RNA-based therapeutic strategies such as antisense oligonucleotides or short interfering RNAs aimed at preventing and decreasing disease risk. We envisage that these data generated under the umbrella of the Global Parkinson’s Genetics Program (GP2) will shed light on the molecular mechanisms involved in the disease process and might pave the way for future clinical trials and therapeutic interventions. This work represents a valuable resource in an underserved population, supporting pioneering research within GP2 and beyond. Deciphering causal and genetic risk factors in all these ancestries will help determine whether interventions, potential targets for disease modifying treatment, and prevention strategies that are being studied in the European populations are relevant to the African and African admixed populations. Implications of all the Available Evidence: We nominate a novel signal impacting GBA1 as the major genetic risk factor for PD in the African and African admixed populations. The present study could inform future GBA1 clinical trials, improving patient stratification. In this regard, genetic testing can help to design trials likely to provide meaningful and actionable answers. It is our hope that these findings may ultimately have clinical utility for this underrepresented population.

The prevalence of restless legs syndrome (RLS) is highest in the elderly in Caucasian populations; the prevalence of RLS in elderly Africans is not known. This study aimed at determining the frequency and associations of RLS in a Nigerian elderly population. The study population comprised of 633 consecutive elderly individuals aged 65–105 years attending the general outpatient clinic of the State Hospital, Ilesa, for minor complaints and routine check-up. The diagnosis of RLS was made using the 2003 minimal criteria of the International Restless Legs Syndrome Study Group. Relevant sociodemographic and clinical data, including sleep duration, were also obtained. Restless legs syndrome was found in 3.5% of the study population with a male-female ratio of 2:1. There was no significant age (p = 0.427) or gender (p = 0.178) influence on the prevalence of RLS except in the 75- to 84-year age group where there was significant male preponderance (p = 0.044). A strong independent association between RLS and sleep duration (OR, 3.229; 95% CI, 1.283–8.486; p = 0.013) and past history of head injury (OR, 4.691; 95% CI, 1.750–12.577; p = 0.002) was found. Our finding support previous reports of a possible lower prevalence of RLS in Africans. Restless legs syndrome independently increases the odds of habitual sleep curtailment in elderly individuals. Head injury may be a risk factor for future RLS; this requires further investigation as indirect evidence for a possible link between RLS and traumatic brain injury exists. Fawale MB, Ismaila IA, Mustapha AF, Komolafe MA, Adedeji TA. Restless legs syndrome in a Nigerian elderly population. J Clin Sleep Med 2016;12(7):965–972.