Lesley King | Sickle cell disease – An ‘evolutionary trade-off’

THE SICKLE gene is believed to have originated in Africa thousands of years ago as a spontaneous mutation (change) to protect against malaria infection. Malaria is widespread in many parts of Africa, especially sub-Saharan Africa.

Persons who have one copy of the sickle gene have sickle cell trait. They are likely to have mild infection and survive malaria, even more so than persons who do not carry the sickle gene. On the other hand, persons who get two copies of the sickle gene, one from each parent, (or one copy of the sickle gene with one copy of another abnormal red cell gene), have sickle cell disease (SCD). Persons with SCD, if they get malaria, are likely to die from complications of their disease. Such is the “evolutionary trade-off”, a gene that arose to protect a population, but at the same time being responsible for a chronic, life-long disease that causes suffering for many.

The slave trade and migration led to the spread of the sickle gene throughout the world. Once thought to be a disease of only black people, SCD is now known to occur in all races and is considered a global disease. In the Caribbean, due to our ancestry, the sickle gene is common. In Jamaica, 10 per cent of our population has the sickle cell trait. Next to Africa, the Caribbean has the second highest percentage of babies born with SCD each year. Based on our current birth rate, 200 babies are born with SCD each year in Jamaica.

SCD is a disease of red blood cells. Normal red cells are round and soft; easily transporting oxygen around the body. Sickle red cells are sickle/banana shaped, stiff and sticky. They tend to clump together and get stuck in the circulation, affecting the delivery of oxygen to the body. It can affect every organ system in the body and lead to complications such as recurrent debilitating bone pain, infection, stroke in children, vision loss and kidney damage, to name a few.

Persons with SCD are challenged throughout their lifetime, not only from the many complications of their disease, but also from mental and social issues that arise when living with disease. The stigma and discrimination that patients face is often a result of lack of understanding, empathy and support that is needed from all levels of society – family/friends, community, school, work and church.

Thankfully, due to years of research leading to a better understanding of the disease, significant advances have been made in healthcare for persons living with SCD which can impact their quality of life. A lot of this work has come from Jamaica, starting with Professor Graham Serjeant and continuing today with the Sickle Cell Unit at The University of the West Indies.

The early years in SCD is extremely high risk for death. In Africa, where most of babies with SCD are born worldwide, 50-80 per cent will die before the age of five years due to lack of resources. Diagnosing SCD early from shortly after birth, enrolling babies in a programme of care, disease education and starting simple interventions such as special vaccines and penicillin (the cheapest antibiotic available) can decrease early childhood deaths. All these simple interventions are available in Jamaica. As a result, in Jamaica, the risk of death in SCD children under five years of age is no different than in non-SCD children once the former are diagnosed at birth and comply with care.

There are now medications that can change how the disease affects a person. For example, reducing pain crises, sick days, hospital visits, and early death. The most well-known of these is Hydroxyurea which has been in use for over 30 years. This is available in Jamaica and is included with drug subsidies on the National Health Fund (NHF) for SCD.

Curative treatments for SCD, such as bone marrow transplant and gene therapy are now possible, but not available in Jamaica. Work continues to find ways to make them safer and more cost-effective for areas where the disease burden is highest.

Since 2012, the Ministry of Health & Wellness has actively partnered with the Sickle Cell Unit and other stakeholders to highlight SCD to bring about changes such as islandwide newborn screening and early childhood care programmes, NHF inclusion, increased training for healthcare workers and provision of special vaccines. All these initiatives have impacted lives of persons with SCD, yet our patients face ongoing struggles. We accept that there is more work to be done.

And so, what began as an evolutionary change to protect against malaria has left the world with a disease that is complexion so many levels. The World Health Organization (2006) and United Nations General Assembly (2008) declared SCD a public health problem. Greater awareness is needed. Better access to healthcare for patients is a priority. Better management of acute problems such as pain crises and other drugs to modify disease are required. Cure for all would be the goal.

Change may not come fast enough for those persons living with disease. Their suffering is real. The solution must be ongoing collaboration between patients and families, healthcare workers, policy makers, researchers, drug companies, etc., which has made, and can continue to make a difference in the lives of persons living with SCD.

Dr Lesley King is head of clinical services at Caribbean Institute for Health Research, UWI. Email: lesley.king@uwi.edu. Send feedback to columns@gleanerjm.com