Medical Genetics and Genomics in Africa
General Perspectives: Genetics is a supradisciplinary science that occupies a central position in the study of biological sciences including human, plant, animal and microbial sciences. It is devoted to the scientific investigation of heredity, variation and disease at all levels of biological life and organization. The main general branches of genetics include human genetics, plant genetics, animal genetics and microbial genetics. Genetics features prominently in biomedical science studies and has implications for and applications to the practice of medicine. The study of genetics helps us to understand and explain biological and pathobiological processes in an organism. It helps us to explain species’ different characteristics, variations and inheritance patterns of those traits. It helps us to understand disease etiopathogenesis, risk, inheritance patterns, and disease clusters in certain population groups. The study of and knowledge about genetic mechanisms has applications not only in medicine, but also in agriculture, animal husbandry, microbial sciences, anthropology, evolution, ecology, and psychology, as well as other fields of science. Genetics has critical impacts on economics, health care and academic activity.
Human Genetics: Human genetics is the branch of genetics that is devoted to the study of the molecular architecture, organization, biological processes and inheritance patterns of genes in humans. Genes are the basic and discrete units of genetics. Genes carry the blueprint of the genetic information that directs the synthesis of proteins or different types of small molecules known as ribonucleic acid (RNA). Genes are contained in chromosomes. The central building structure of chromosomes is deoxyribonucleic acid (DNA). Genetic information is stored in the DNA in sequences of four bases, adenine (A), cytosine (C), guanine (G) and Thymine (T)) which are strung along ribbons of sugar-phosphate molecules in the shape of a double helix. The double helix forms the backbone of DNA. The double helix is held together by hydrogen bonds between two bases. Each base will only form a hydrogen bond across the helix always with a specific opposing base i.e. A with T and C with G. Genetic information is stored in a linear and specific arrangement of the nucleotide bases along the DNA helix. The arrangement is like a text of individual letters and words in a defined sequence that makes biological sense. The arrangement of the bases along the DNA is a specific read-only memory device of genetic information known as the genetic code. The genetic code uses the four nucleotide bases in combinations of three building blocks called the triplet codon. A gene is a discrete unit of genetic information made up of a sequence of triplet codons. The genetic information in a gene is equivalent to a single sentence in a text. In any given organism the size and number of genes vary depending on the complexity of the organism. In single celled organisms (known as prokaryotes), the number of genes ranges from 500 to 5000. In more complex multicellular organisms (known as eukaryotes), like humans, the number ranges from 6000 to 40,000. In eukaryotes, genes are located along the complex structures known as chromosomes which are located in the cell’s nucleus and come in homologous pairs – one from the mother and the other from the father. In humans, chromosomes come in 23 pairs, consisting of chromosomes 1-12 collectively referred to as autosomes and the sex chromosomes X and Y in males and two X chromosomes in females. Genes can change the content of their genetic information. A change of genetic information in a gene is referred to as a mutation. Mutations can be beneficial, deleterious or have no impact on an organism. Mutations can be the basis of a heritable disorder such as sickle cell disease, and generally nonheritable disorders such as cancer (certain cancers are heritable). Mutations can also explain variability of traits, survival and fitness within members of a population group. Mutations are the basis of species evolution.
Human Genetics in Africa: Human genetics in Africa is almost ninety percent genomics and population genetics in terms of focus, number of dedicated researchers and funding. Over 90% of human genetics research funding across Africa is provided by the National Institutes of Health (NIH), Welcome Trust, Fogarty International and the National Human Genome, Research institute (NHGRI). Most of this funding is channeled through the Human Heredity and Health in Africa (H3Africa) program. African sourced funding is miniscule. The African Society of Human Genetics (AfSHG), founded in 2004, is the formal professional organization of the few African human geneticists on the continent and in the diaspora. Except in South Africa and in a few other African countries, there are no formal and rigorous human genetics training programs across Africa. Most African human geneticists are trained outside of Africa and many remain overseas to do their research.
The term genomics defines the new sub-field of genetics that is devoted to studying entire genomes rather than only selected genes. The genome refers to the totality of all the genetic material of a cell or of an individual. Genomics refers to the study of the structure and functions of genomes; it includes the study and characterization of the structure, organization and function of the entire nucleotide sequence, all genes and their chromosomal localization, chromosomal associated proteins and the architecture of the nucleus. Genomic techniques at once study the genetic, molecular and cellular structure, organization and function of the genome in an integrated fashion. The aims of genomic studies are manifold, including analysis of the transcriptome (entire nucleotide sequences, all genes and sequences, all molecules involved in transcription and translation and their regulation); analysis of the proteome (all proteins an organism produces); functional genomics (analysis of all genes and their functional repertoire); comparative genomics (correlating genome maps with the evolution of genomes), and bioinformatics (assembly, storage and management of data). Evidently, and when taken together, genetics and genomics are critical in the entire medical and biological sciences enterprise.
Medical Genetics in Africa: Medical genetics across Africa (except South Africa) is rudimentary or non-existent in the established health care systems. There are only a handful formally trained African medical geneticists; almost all are trained outside of Africa. With the exception of South Africa, there are no rigorous medical genetics training programs in any academic centers across Africa. There is no formal organization of the small community of African medical geneticists let alone a standards setting and certifying body like the American College of Medical Genetics and Genomics and the American Board of Medical Genetics, as exist in the US. In North America organized medical genetics was initiated and spearheaded by a small group of spirited clinicians and researchers. In the beginning medical genetics grew out of basic science and human genetics departments, and the clinical disciplines of internal medicine and paediatrics. In Europe, Canada and the US, some of the pioneer human geneticists were plant and Drosophila geneticists in their early careers who later helped to shape and organize the emerging discipline of medical genetics. As an organized discipline, medical genetics emerged first in Europe in the 1960s. In North America, organized medical genetics emerged in Canada in the early 1970s with the formation of the Canadian College of Medical Genetics, and in the early 1980’s in the US, with the formation of the American College of Medical Genetics and the American Board of Medical Genetics.
Medical genetics is a super discipline; a fully-fledged department and service includes the sub-disciplines of clinical genetics, biochemical/metabolic genetics, molecular genetics and cytogenetics. In addition at certain more specialized centres the sub-disciplines of cancer genetics, immunogenetics and pharmacogenetics are part of the medical genetics enterprise. Further, genetic counselors are a critical component of medical genetic services and are an integral part of organized medical genetics. Genetic counselors perform the essential role of frontline interfacers of medical genetics services and the public served. They are the first contact for families seeking genetics services and help explain, risk, inheritance patterns and outcome of specific genetic disorders.
Africa needs a motivated, farsighted and inspirational small group of medical geneticists to spearhead advocating for the institution, organization and incorporation of medical genetics in the medical school curriculum, and as departments or divisions within the medical school departmental architecture. To benefit society, medical genetics should be integrated into the health care systems across Africa. Further, and to prepare future medical geneticists, the teaching of genetics should be incorporated into high school, undergraduate and graduate school curricula across Africa. This will foster a generation of proficient young people who can then make informed decisions about pursuing careers in the super discipline of medical genetics. Aspiring medical genetics professionals can hold medical, doctorate or even master’s level degrees. Only individuals aspiring to be clinical geneticists need hold an MD degree. All others including aspirants for careers in cytogenetics, molecular genetics, biochemical/metabolic genetics can be MDs or PhDs or both. Genetics counselors usually hold a master’s level degree.
Human Genomics in Africa: The Human Genome Project (HGP) – a remarkable feat of collaborative human explorative ingenuity – begun on October 1, 1990 and completed in April 2003, gave us the ability, for the first time, to read nature’s complete genetic blueprint for building a human being. In the context of Africa the HGP remains incomplete as the vast majority of the characterized genome is still European and only 2% is from people of African descent. And yet, the genetic diversity in Africa is greater than in any other region in the world. This provides a perfect setting for human genome, pharmacogenomics and medical genetics research. It also provides a unique setting for medical genetics and genomics training and clinical service as an integral part of health care. Studies have shown that genetic variations found among certain African populations have never previously been recorded, because most human genetics studies focus on people of European descent. This oversight could have a significant impact on global human health, as the variants in the African populations are studied, included genes associated with cardiovascular and metabolic diseases. To quote Dr. Deepti Gurdasani, a researcher at Queen Mary University of London who led a genomics research project in Uganda, “Two individuals within an African population will be much more different than two individuals within a European population,” “For example, if you had a gene that was not variable at all in Europeans, you could not find an association with disease,” says Gurdasani. If there was variability in the same gene in people of African descent, that could lead to the development of a drug that could be used globally she says. The lack of African genetic material constitutes a significant obstacle to understanding how our bodies function and knowing our susceptibility to disease. African genomes are not only humanity’s oldest but our most diverse, and that diversity holds within it an almost unfathomable potential – from scientific breakthroughs to gene editing to the rewriting of our evolutionary history – the very story we tell ourselves about ourselves. Without a vibrant human genetics society, an organized medical genetics community, and a process for setting standards and certification of practitioners of medical genetics, Africa risks not benefiting from its genomic treasure. The time for organized medical genetics is now. It is an imperative that should engage African medical geneticists across Africa and in the diaspora. It is a project that calls for the full support of policy makers across Africa. It will need the involvement of all genetic professionals, academic centres and educational systems across Africa to integrate genetics as an essential subject to be taught at all levels of the educational systems.
About the Author
Joachim Kapalanga, MD, PhD, FACMG, DABMG, FAAP, DABP is an Adjunct Professor at Western University and Assistant Professor at McMaster University, Departments of Paediatrics. Dr. Kapalanga trained as a human geneticist at the University of Guelph, as a medical geneticist at Queen’s University and as a clinical geneticist at Yale University. He is a consultant paediatrician and medical geneticist at Grey Bruce Health Services, Owen Sound and at the Summerside Medical Centre, Summerside PEI.
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