Papers by Ambroise Wonkam
Journal of medical genetics, Jan 6, 2016
Pharmaceuticals, 2015
The most accessible points of call for most African populations with respect to primary health ca... more The most accessible points of call for most African populations with respect to primary health care are traditional health systems that include spiritual, religious, and herbal medicine. This review focusses only on the use of herbal medicines. Most African people accept herbal medicines as generally safe with no serious adverse effects. However, the overlap between conventional medicine and herbal medicine is a reality among countries in health systems transition. Patients often simultaneously seek treatment from both conventional and traditional health systems for the same condition. Commonly encountered conditions/diseases include malaria, HIV/AIDS, hypertension, tuberculosis, and bleeding disorders. It is therefore imperative to understand the modes of interaction between different drugs from conventional and traditional health care systems when used in treatment combinations. Both conventional and traditional drug entities are metabolized by the same enzyme systems in the human body, resulting in both pharmacokinetics and pharmacodynamics interactions, whose properties remain unknown/unquantified. Thus, it is important that profiles of interaction between different herbal and conventional medicines be evaluated. This review evaluates herbal and conventional drugs in a few African countries and their potential interaction at the pharmacogenomics level.
Human Genomics, 2015
In recent years, the translation of genomic discoveries into mainstream medical practice and publ... more In recent years, the translation of genomic discoveries into mainstream medical practice and public health has gained momentum, facilitated by the advent of new technologies. However, there are often major discrepancies in the pace of implementation of genomic medicine between developed and developing/resource-limited countries. The main reason does not only lie in the limitation of resources but also in the slow pace of adoption of the new findings and the poor understanding of the potential that this new discipline offers to rationalize medical diagnosis and treatment. Here, we present and critically discuss examples from the successful implementation of genomic medicine in resource-limited countries, focusing on pharmacogenomics, genome informatics, and public health genomics, emphasizing in the latter case genomic education, stakeholder analysis, and economics in pharmacogenomics. These examples can be considered as model cases and be readily replicated for the wide implementation of pharmacogenomics and genomic medicine in other resource-limited environments.
OMICS: A Journal of Integrative Biology, 2015
Variants in BCL11A were previously associated with fetal hemoglobin (HbF) levels among Cameroonia... more Variants in BCL11A were previously associated with fetal hemoglobin (HbF) levels among Cameroonian sickle cell disease (SCD) patients, however explaining only ∼2% of the variance. In the same patients, we have investigated the relationship between HbF and two SNPs in a BCL11A erythroid-specific enhancer (N = 626). Minor allele frequencies in rs7606173 and rs1427407 were 0.42 and 0.24, respectively. Both variants were significantly associated with HbF levels (p = 3.11e-08 and p = 6.04e-06, respectively) and explained 8% and 6.2% variations, respectively. These data have confirmed a stronger effect on HbF of genomic variations at the BCL11A erythroid-specific enhancer among patients with SCD in Cameroon, the first report on a West African population. The relevance of these findings is of prime importance because the disruption of this enhancer would alter BCL11A expression in erythroid precursors and thus HbF expression, while sparing the induced functional challenges of any alterations on the expression of this transcription factor in non-erythroid lineages, thus providing an attractive approach for new treatment strategies of SCD.
Public Health Genomics, 2015
Management of sickle cell disease (SCD) in Africa needs to be accompanied by various preventive s... more Management of sickle cell disease (SCD) in Africa needs to be accompanied by various preventive strategies, including early detection via prenatal genetic diagnosis (PND). Contrary to Cameroonian doctors who considered termination of an affected pregnancy (TAP) for SCD in 36.1%, the majority of parents (62.5%) with affected children accepted TAP in principle. In practice, most women opted for TAP (90%), justified by a huge psycho-social burden. The ethical and legal challenges of PND prompted the need to explore the use of genetics for secondary prevention of SCD. In 610 Cameroonian SCD patients, the genomic variations in two principal foetal haemoglobin-promoting loci were significantly associated with foetal haemoglobin levels. In addition, the co-inheritance of a 3.7-kb α-globin gene deletion and SCD was associated with a late disease onset and possibly improved survival: there was a much higher allele frequency of the 3.7-kb α-globin gene deletion in SCD patients (∼40%) than in haemoglobin AA controls (∼10%). The data indicate the urgent need to develop and implement policy actions in sub-Saharan Africa on at least four levels: (1) the implementation of SCD screening practices and early neonatal follow-up; (2) the development and incorporating of socio-economic support to alleviate the burden of SCD on affected families; (3) the exploration of the appropriateness of the medical abortion laws for SCD, and (4) the development of national plans for genetic medicine, including research on genomic variants that affect the phenotypes of SCD, in order to potentially use them for anticipatory guidance. © 2015 S. Karger AG, Basel.
OMICS: A Journal of Integrative Biology, 2015
The use of pharmacogenomics (PGx) knowledge in treatment of individual patients is becoming a com... more The use of pharmacogenomics (PGx) knowledge in treatment of individual patients is becoming a common phenomenon in the developed world. However, poorly resourced countries have thus far been constrained for three main reasons. First, the cost of whole genome sequencing is still considerably high in comparison to other (non-genomics) diagnostics in the developing world where both science and social dynamics create a dynamic and fragile healthcare ecosystem. Second, studies correlating genomic differences with drug pharmacokinetics and pharmacodynamics have not been consistent, and more importantly, often not indexed to impact on societal end-points, beyond clinical practice. Third, ethics regulatory frames over PGx testing require improvements based on nested accountability systems and in ways that address the user community needs. Thus, CYP2B6 is a crucial enzyme in the metabolism of antiretroviral drugs, efavirenz and nevirapine. More than 40 genetic variants have been reported, but only a few contribute to differences in plasma EFV and NVP concentrations. The most widely reported CYP2B6 variants affecting plasma drug levels include c.516G > T, c.983T > C, and to a lesser extent, g.15582C > T, which should be considered in future PGx tests. While the first two variants are easily characterized, the g.15582C > T detection has been performed primarily by sequencing, which is costly, labor intensive, and requires access to barely available expertise in the developing world. We report here on a simple, practical PCR-RFLP method with vast potentials for use in resource-constrained world regions to detect the g.15582C > T variation among South African and Cameroonian persons. The effects of CYP2B6 g.15582C > T on plasma EFV concentration were further evaluated among HIV/AIDS patients. We report no differences in the frequency of the g.15582T variant between the South African (0.08) and Cameroonian (0.06) groups, which are significantly lower than reported in Asians (0.39) and Caucasians (0.31). The g.15582C/T and T/T genotypes were associated with significantly reduced EFV levels ( p = 0.006). This article additionally presents the policy relevance of the PGX global health diagnostics and therefore, collectively makes an original interdisciplinary contribution to the field of integrative biology and personalized medicine in developing world. Such studies are, in fact, broadly important because resource-constrained regions exist not only in developing world but also in major geographical parts of the G20 nations and the developed countries.
Cardiovascular Journal Of Africa, 2015
Sickle cell disease (SCD) has a high prevalence in sub-Saharan Africa. There are several cardiova... more Sickle cell disease (SCD) has a high prevalence in sub-Saharan Africa. There are several cardiovascular phenotypes in SCD that contribute to its morbidity and mortality. SCD is characterised by marked clinical variability, with genetic factors playing key modulating roles. Studies in Tanzania and Cameroon have reported that singlenucleotide polymorphisms in BCL11A and HBS1L-MYB loci and co-inheritance of alpha-thalassaemia impact on foetal haemoglobin levels and clinical severity. The prevalence of overt stroke among SCD patients in Cameroon (6.7%) and Nigeria (8.7%) suggests a higher burden than in high-income countries. There is also some evidence of high burden of kidney disease and pulmonary hypertension in SCD; however, the burden and genetics of these cardiovascular conditions have seldom been investigated in Africa. Several H3Africa projects are focused on cardiovascular diseases and present major opportunities to build genome-based research on existing SCD platforms in Africa to transform the health outcomes of patients.
Omics : a journal of integrative biology, 2015
Studies of hemoglobin S haplotypes in African subpopulations have potential implications for pati... more Studies of hemoglobin S haplotypes in African subpopulations have potential implications for patient care and our understanding of genetic factors that have shaped the prevalence of sickle cell disease (SCD). We evaluated HBB gene cluster haplotypes in SCD patients from Cameroon, and reviewed the literature for a global distribution. We reviewed medical records to obtain pertinent socio-demographic and clinical features for 610 Cameroonian SCD patients, including hemoglobin electrophoresis and full blood counts. RFLP-PCR was used to determine the HBB gene haplotype on 1082 chromosomes. A systematic review of the current literature was undertaken to catalogue HBB haplotype frequencies in SCD populations around the world. Benin (74%; n=799) and Cameroon (19%; n=207) were the most prevalent haplotypes observed among Cameroonian patients. There was no significant association between HBB haplotypes and clinical life events, anthropometric measures, hematological parameters, or fetal hemo...
International archives of medicine, 2014
Hepatitis B virus (HBV) infection is one of the most serious occupational hazards faced by health... more Hepatitis B virus (HBV) infection is one of the most serious occupational hazards faced by healthcare workers. Surgical personnel are particularly at risk. HBV infection is preventable by vaccination, but no previous study has assessed HBV vaccination coverage among healthcare workers in Cameroon. We assessed knowledge of risk factors of HBV infection, awareness of HBV vaccine, and vaccination status of surgical residents in Cameroon. A structured pretested questionnaire was administered to 49 of the 70 surgical residents in Cameroon during the 2011-2012 academic year. Since the beginning of their residency program, 28 (57.1%) had had at least one accidental exposure to blood, with a median of 2 (range 1 to 25) exposures. Most of them had a good knowledge of risk factors for HBV infection. Although 98.0% (n = 48) were aware of the HBV vaccine, and 89.8% (n = 44) knew that they were at high risk of infection, only 24.5% (n = 12) had received a full course of at least three doses of t...
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde, Jan 25, 2011
Studies from Europe and North America suggest that 20 - 50% of patients with dilated cardiomyopat... more Studies from Europe and North America suggest that 20 - 50% of patients with dilated cardiomyopathy (DCM) may have familial disease. There is little information on the frequency and clinical genetics of familial DCM in Africa. To determine the frequency and probable mode of inheritance of familial DCM in patients referred for investigation of the cause of DCM at a tertiary centre in Cape Town. We conducted a retrospective analysis of consecutive patients diagnosed with DCM between 1 February 1996 and 31 December 2009 to determine the frequency of familial disease. Of 109 unrelated patients with DCM, 29 (26.6%) had familial disease. Their mean age of onset of cardiomyopathy (28.01 (standard deviation (SD) 15.33) years) was significantly younger than that for non-familial cases (39.1 (SD 12.6) years) (p=0.001). Male predominance (N=21, 72.4%) and racial distribution (15 (48.3%) coloured patients, 10 (34.5%) black Africans, 4 (13.8%) white individuals, and 1 (3.4%) of Indian descent) o...
Congenital anomalies, 2011
Familial cases of isolated abdominal wall defects with variable expressivity in more than one gen... more Familial cases of isolated abdominal wall defects with variable expressivity in more than one generation have rarely been observed. We report four affected individuals within a small three-generation family with either variable non-syndromic abdominal wall defects or external genital anomalies. We discuss the possible transmission of non-syndromic abdominal wall defects. It could be hypothesized that similar developmental defects may result in anomalies like hypospadias in males or developmental anomalies of the labia minora or labia majora in females.
International Journal of Gynecology & Obstetrics, 2015
Omics : a journal of integrative biology, 2014
Scholarship knows no geographical boundaries. This science diplomacy and biotechnology journalism... more Scholarship knows no geographical boundaries. This science diplomacy and biotechnology journalism article introduces an original concept and policy petition to innovate the global translational science, a Science Peace Corps. Service at the new Corps could entail volunteer work for a minimum of 6 weeks, and up to a maximum of 2 years, for translational research in any region of the world to build capacity manifestly for development and peace, instead of the narrow bench-to-bedside model of life science translation. Topics for translational research are envisioned to include all fields of life sciences and medicine, as long as they are linked to potential or concrete endpoints in development, foreign policy, conflict management, post-crisis capacity building, and/or peace scholarship domains. As a new instrument in the global science and technology governance toolbox, a Science Peace Corps could work effectively, for example, towards elucidating the emerging concept of "one heal...
Science (New York, N.Y.), Jan 20, 2014
Blood Cells, Molecules, and Diseases, 2014
Background: Keratitis-Ichthyosis-Deafness (KID) syndrome (OMIM 148210) is a congenital ectodermal... more Background: Keratitis-Ichthyosis-Deafness (KID) syndrome (OMIM 148210) is a congenital ectodermal defect that consists of an atypical ichthyosiform erythroderma associated with congenital sensorineural deafness. KID appears to be genetically heterogeneous and most cases are caused by GJB2 mutations. Mutations in African patients have been rarely described. Case presentation: We report on two unrelated Cameroonian individuals affected with sporadic KID, presenting with the classic phenotypic triad. The two patients were heterozygous for the most frequent p.Asp50Asn mutation. This first report in patients from sub-Saharan African origin supports the hypothesis that the occurrence of KID due to p.Asp50Asn mutation in GJB2 seems not to be population specific. Conclusions: Our finding has implication in medical genetic practice, specifically in the molecular diagnosis of KID in Africans. These cases also reveal and emphasize the urgent need to develop appropriate policies to care for patients with rare/orphan diseases in Sub-Saharan Africa, as many of these cases become more and more recognizable.
Cardiovascular Journal Of Africa, 2013
Peripartum cardiomyopathy (PPCM) is a form of pregnancyrelated heart failure that is associated w... more Peripartum cardiomyopathy (PPCM) is a form of pregnancyrelated heart failure that is associated with considerable morbidity and mortality. Most patients present with acute postpartal heart failure that otherwise resembles the clinical presentation of dilated cardiomyopathy (DCM). There is increasing recognition that PPCM may be due to genetic factors in a significant proportion of cases. There is evidence that at least 7% of cases of PPCM may be part of the spectrum of familial DCM. We report on two cases of PPCM, with relatives demonstrating familial DCM, both patients displaying autosomal dominant patterns of inheritance, and showing severe cardiomyopathy among proband and affected relatives. Family screening for familial DCM should be indicated in all cases of unexplained PPCM.
Journal of Community Genetics, 2013
This study aims to evaluate the attitudes of a group of South African parents with a preschool ch... more This study aims to evaluate the attitudes of a group of South African parents with a preschool child with Down syndrome (DS) towards prenatal diagnosis (PND) and termination of a Down syndrome-affected pregnancy (TAP). This study employs a qualitative phenomenological approach with the use of semi-structured interviews. Twelve participants were recruited from two state sector hospitals in Cape Town, South Africa. Thematic analysis was used to interpret the data. The participants had a positive attitude towards PND and felt that it was every parent's right to have the option. They considered a benefit of PND the fact that it allowed parents time to prepare for the arrival of a baby with DS. The induced miscarriage risk associated with invasive prenatal testing procedures caused major negative feelings. They were totally opposed to the termination of a Down syndrome-affected pregnancy due to their personal experience, moral, ethical or religious convictions. South African parents of preschool children with Down syndrome are comfortable with PND for Down syndrome; however, they do not support TAP. These findings will provide health care providers with further insight into the motivations behind the decisions their patients make.
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Papers by Ambroise Wonkam