Sickle cell disease is caused by a variant of the beta-globin gene called sickle hemoglobin (Hb S). Inherited autosomal recessively, either two copies of Hb S or one copy of Hb S plus another beta-globin variant (such as Hb C) are required for disease expression. Hb S carriers are protected from malaria infection, and this protection probably led to the high frequency of Hb S in individuals of African and Mediterranean ancestry. Despite this advantage, individuals with sickle cell disease exhibit significant morbidity and mortality. Symptoms include chronic anemia, acute chest syndrome, stroke, splenic and renal dysfunction, pain crises, and susceptibility to bacterial infections. Pediatric mortality is primarily due to bacterial infection and stroke.
In adults, specific causes of mortality are more varied, but individuals with more symptomatic disease may exhibit early mortality. Disease expression is variable and is modified by several factors, the most influential being genotype. Other factors include beta-globin cluster haplotypes, alpha-globin gene number, and fetal hemoglobin expression. In recent years, newborn screening, better medical care, parent education, and penicillin prophylaxis have successfully reduced morbidity and mortality due to Hb S
Molineaux and co-workers 2001, after some research in northern Nigeria, correctly summarised the situation when they wrote in 2002, “There is no other known inherited disorder present at such high frequency in a large population and of comparable severity as sickle cell anaemia in Africa.
With rising standards of living and control of malaria, sickle cell anaemia will become an immense medical, social and economic problem throughout the continent.” In sheer numbers, Nigeria has the largest burden of sickle cell disorder (SCD) in the whole world. Carriers of the sickle cell gene (Hb AS) have, over the past centuries, flourished and multiplied in tropical sub-Saharan Africa because their carrier status protected them from succumbing to the deadly
falciparum malaria prevalent in the Region. In other words, they enjoyed a survival advantage over their peers who had not inherited the gene (Hb AA) and those who had inherited it from both parents and therefore had sickle cell anaemia (Hb SS) ( WHO,2005).
Although countries around Nigeria also have an S gene carrier frequency of about 1 in 4 of their populations, Nigeria’s large population has ensured that over 40 million Nigerians are healthy carriers of the S gene. This number of carriers far exceeds the total population of every other affected African country and indeed, of several of them put together. Consequently, about 150,000 Nigerian children are born each year with sickle cell anaemia (HbSS), the prevailing type of sickle cell disorder (SCD) in this Region (UNESCO 2005).
For an old disorder with a birth rate of 1 in 50 babies, the level of awareness is relatively low. This is not because of a lower birth rate previously, but because the affected children rarely survived childhood and were therefore less likely than now, to be encountered in secondary schools, in universities and in the workplace. Their peers and relatives now have the opportunity to observe their periodic pain crises and, sadly, occasionally, their premature deaths. This
familiarity has heightened awareness (Resta et al, 2006).
The other factor boosting awareness is the development of Sickle Cell Clubs, with attendant publicity, over the past two to three decades. Despite its 2% birth incidence2, the estimated population of SCD affected persons in Nigeria is only about one million, owing to a high rate of premature deaths (Hallowel and Richard 2005).
Unfortunately, the increasing awareness has not been matched by the development of a well resourced national policy. This has curtailed the dissemination of accurate and unbiased public information and education about the disorder and has fuelled the growth of myths, misinformation, inappropriate treatment, frustration and stigmatisation.
The frustration has kindled the desire in many Nigerians to do something about sickle cell disorder. What needs to be done often appears deceptively easy and is usually not fully thought out and remains a subject of confusion and controversy even among health care workers.
In this regard, one frequently hears talk of eradication of the disorder while the wider context of management and control is invariably overlooked.(Aalfs et al.,2003)
- Selective Mating and the Eradication of SCD
Determination of the haemoglobin genotype plays a vital role in eradication of SCD by selective mating. It appears so logical and simple that many individuals, religious bodies and charitable organisations have tried to implement it themselves by screening young people and instructing those shown to be carriers to avoid choosing spouses who also have the sickle cell gene. Some churches even refuse to marry them.
This strategy is based on the false assumption that SCD can be easily eradicated by mass population screening of haemoglobin genotypes as a basis for coercive selection of spouses,(Garson et al 2006). The Military Administrator of Oyo State, had, in 2002, proposed a punitive edict aimed at prohibiting marriages between carriers of the sickle cell gene, but the conference of Solicitor–Generals in Nigeria thwarted its introduction by declaring that it was unconstitutional and offended the human rights charter to which Nigeria is a signatory (the guardian newspaper editorial.2005). The reality however, is that enforced selective mating of couples has never been shown anywhere in the world to have reduced the incidence of any inherited disorder.
Coordination and Harmonisation of Institutions and Programmes (SICKLE CELL)
The Sickle Cell Foundation Nigeria (SCFN) was established to address the problem of SCD in Nigeria in a systematic, scientific and sustainable manner. It has achieved its first goal of developing, in accordance with WHO recommendation 7, a comprehensive National Sickle Cell Centre in Lagos. The intention is for each State to have a collaborating Sickle Cell Centre that will supervise and coordinate the programmes and activities of all Sickle Cell Clubs within that State.
- Training and Capacity Building
The National Sickle Cell Centre is engaged in training various cadres of health care personnel in order to improve the standard of preventive and curative care available to persons with SCD.
Genetic counselling is not marriage counselling. Sickle cell disorder should be sensitively managed within the community. Otherwise, people living with SCD or who are healthy carriers of the gene may feel stigmatised and be tempted to conceal, deny or falsify their haemoglobin (Hb) genotype status. This state of affairs can be counter-productive to efforts aimed at managing the disorder in the community. The importance of genetic counselling in preventing these undesirable outcomes is well established. In counselling, the client is a person with SCD, his close family member or a healthy carrier of the sickle cell gene or the gene of some other haemoglobin variant such as Hb AC. The role of the counsellor is to ensure that the clients are given accurate unbiased information necessary to assist them to reach their own decisions on reproductive behaviour or any other course of action related to the disorder. Their decision must be respected and supported by the counsellor and confidentiality must be maintained. Failure to do so usually alienates the client to the detriment of the relationship between counsellor and client.
- Effective counselling is informative, confidential, non-directive and supportive.
It requires skills that are best acquired through appropriate training and experience. Doctors who see many patients with SCD should endeavour to acquire the necessary skills and, if they have many patients, employ the services of one or more trained nurse-counsellors.