In Nigeria, the health sector comprises a combination of public (government-run) and private facilities. Healthcare is organized into three tiers: primary, secondary, and tertiary, with tertiary facilities such as university teaching hospitals and specialist hospitals offering the highest level of care. In 2020, total health expenditure as a percentage of GDP in Nigeria stood at 3.38%.
The country has a national health insurance scheme, established by decree in 1999 and later re-enacted as the National Health Insurance Scheme Act Cap, N42 Laws of the Federation of Nigeria 2004. Launched in 2005, the scheme aims to deliver quality healthcare to Nigerians at an affordable cost through various prepayment systems. However, participation is voluntary, and currently, only a small fraction of the population is covered.
Consequently, health insurance coverage is not universal, and most Nigerians have to pay out-of-pocket for the majority of their healthcare expenses. The National Health Act 2014, signed into law on October 31, 2014, provides a legal framework for regulating, developing, and managing Nigeria’s health system. It sets standards for delivering health services and addresses various related matters. While most national health policy documents do not explicitly mention genetic services or genomic medicine, sickle cell disease is an exception.
Common Genetic Disorders in Nigeria
Sickle cell disease (SCD) is likely the most prevalent severe genetic disorder in Nigeria, affecting approximately 2%–3% of newborns. Sickle cell trait impacts up to a quarter of the population, with surveys dating back to the 1950s indicating a stable prevalence of 22%–25% for the trait. With Nigeria’s population estimated at around 200 million, it is plausible that Nigeria hosts the largest population globally affected by Sickle cell disease or at risk of having children with Sickle cell disease.
Another prevalent monogenic disorder is glucose-6-phosphate dehydrogenase (G6PD) deficiency, predominantly the African type (GdA-), which primarily presents an increased risk of neonatal jaundice and drug-induced hemolysis. Significant advancements in understanding G6PD deficiency were achieved through research conducted in Ibadan, where the first neonatal screening program for G6PD deficiency by electrophoresis was also established.
Oculocutaneous albinism is reportedly common in the eastern region of Nigeria; however, comprehensive molecular genetic studies estimating its prevalence and distribution are currently lacking. Congenital malformations are prevalent and contribute significantly to morbidity and mortality in childhood. Autosomal trisomies, particularly trisomy 21 (Down syndrome), are also frequently observed.
Overall, there is a lack of a comprehensive understanding of the relative burden of various genetic disorders in Nigeria due to the absence of newborn screening, limited diagnostic facilities, and the absence of population-based registries.
Medical Genetics in Nigeria
The medical literature originating from Nigeria predominantly consists of case reports or case series documenting genetic disorders based on clinical observations. For instance, instances of dystrophia myotonica in Nigerian families have been reported, and the first documented case of hereditary anhidrotic ectodermal dysplasia in Africa was identified in a Nigerian family.
However, the inaugural medical genetics service in Nigeria was established in the early 1970s in Ibadan, featuring both clinical and cytogenetics services. Staffed by a pediatric clinical geneticist and a cytogeneticist, this unit provided clinical genetics services and conducted groundbreaking research on autosomal trisomies, skeletal dysplasias, and other dysmorphic disorders. The pioneering work conducted by this unit laid the groundwork for subsequent genetics services and research in Ibadan.
Presently, there remains a scarcity of medical geneticists and genetic counselors in Nigeria. Most patients diagnosed with genetic disorders are managed by pediatricians, some of whom possess an interest in genetics, while others are treated by specialists. Molecular diagnostic facilities, including prenatal diagnosis capabilities, are still suboptimal and not widely accessible. Consequently, opportunities for training in medical genetics are limited within the country, necessitating prospective trainees to seek education abroad.
Although several centers, both public and private, are equipped to perform DNA extraction, only a few laboratories have the capacity to conduct routine genotyping or sequencing for patients onsite. As a result, the majority of molecular diagnostic procedures are still outsourced to facilities outside the country. However, a select few laboratories, notably the Sickle Cell Foundation of Nigeria, offer PCR-RFLP analysis for detecting the sickle cell mutation.
Genetics Research in Nigeria
Genetics research in Nigeria has undergone significant development over time, with early studies primarily consisting of case series. A study in 1982, spanning nine years, revealed an incidence of Down syndrome in Ibadan, demonstrating that the disorder is not uncommon in Nigeria. Cytogenetic analysis showed that the majority of cases (about 96%) were regular trisomy 21, with a smaller percentage attributed to translocations and mosaics. Similar studies also established the incidence at birth for other genetic conditions such as trisomy 18, trisomy 13, and Turner syndrome. Additionally, retrospective studies have documented cases of neurodegenerative disorders and congenital malformations, including their prevalence and contribution to morbidity.
In the 1990s, research expanded to include molecular genetics markers in complex disorders like hypertension, obesity, and diabetes. Studies investigated genetic variants’ association with these conditions, providing insights into the genetic basis of susceptibility. Genome-wide linkage studies, often involving Nigerian populations, were conducted through international collaborations, contributing to the identification of genetic loci linked to various diseases, including obesity and diabetes.
Recent studies have focused on medical genetic disorders more directly, such as orofacial clefts, congenital deafness, and congenital heart defects (CHD). These studies have identified novel mutations and rare variants associated with these conditions, enhancing our understanding of their genetic basis. Ongoing projects, including collaborative efforts, aim to further explore the genomics of CHD and other disorders, utilizing advanced genomic techniques such as whole exome sequencing.
Nigerian clinicians are actively participating in international initiatives like the NHGRI Atlas of Human Malformation Syndromes, contributing to comparative research and facilitating the development of medical genetics in Nigeria. Overall, while challenges remain, genetics research in Nigeria is progressing, enabling a deeper understanding of genetic disorders and their management within the population.
Nigeria in International Genetics and Genomics Initiatives
Nigerian populations have been actively engaged in various international genomics initiatives following the sequencing of the human genome. In the initial phase of the International HapMap Project, the Yoruba ethno-linguistic group was designated as the African reference population. Subsequently, the 1000 Genomes Project expanded its scope to include two Nigerian ethno-linguistic groups: the Yoruba and the Esan. These projects focused on exploring population genetics characteristics, including genetic and haplotype diversity, admixture, and signs of selection.
A more recent endeavor in genomics, particularly concerning health and disease, is the Human Heredity and Health in Africa (H3Africa) Project. Jointly funded by the National Institutes of Health (NIH) and the Wellcome Trust, H3Africa has allocated significant grants to African investigators for genomics research, capacity enhancement, and infrastructure improvement for genome research across the continent. Nigerian sites actively participate in various H3Africa projects, covering studies on stroke, chronic kidney disease, febrile illness, cervical cancer, glaucoma, and ethical, legal, and social issues (ELSI), among others. Moreover, Nigeria hosts several H3Africa bioinformatics nodes.
These collaborative projects are instrumental in bolstering the development of genomics and genetics facilities in Nigeria, including genotyping, sequencing, and bioinformatics capabilities. They also play a crucial role in workforce development, enhancing manpower in the field of genetics and genomics. Furthermore, these initiatives mark the first systematic exploration of certain disorders within Nigeria. The expertise and infrastructure cultivated through these projects are poised to serve the country well, fostering a critical mass of expertise in medical genetics and genomic medicine.
Bottom Line
The current state of medical genetics and genomic medicine in Nigeria falls short of adequately addressing the population’s needs. Nevertheless, significant progress is underway, driven by recent funding opportunities for research projects, infrastructural improvements, and the training of essential personnel. These developments lay the groundwork for advancing medical genetics and genomic medicine in the country.
To further advance in this field, national policies and programs are imperative. These initiatives should focus on enhancing screening and detection of genetic disorders, coordinating clinical management, facilitating the training of medical genetics and genomics professionals, and promoting research into genetic disorders that disproportionately affect Nigerians. Such comprehensive efforts are essential for ensuring that the healthcare system is equipped to address the genetic health needs of the population effectively.
