19 June was declared World sickle cell day by the United Nations General assembly in 2008 to highlight awareness and understanding of this considerable health issue: in sub-Saharan Africa, this hereditary condition is one of the leading causes of early childhood mortality and remains a significant cause of premature death in adults.
In the UK, SCD affects around 13,000 individuals with approximately 300 new babies born and identified by the National neonatal screening programme every year. Homozygous SCD (Hb SS) is the most common genotype in the UK and clinically a heterogeneous condition with many factors impacting on the clinical course. With advances in our understanding of the patho-biology of sickle cell disease we have come to appreciate that what was once thought to be a condition with a straightforward genetic explanation, is actually far more complex and challenging.
In particular, multiple patho-physiological mechanisms are thought to lead to vaso-occlusion and tissue injury in SCD. Information from the National Haemoglobinopathy register is starting to help inform our understanding of the causes of morbidity and mortality for UK patients and over time we will have a better idea of the current life expectancy.
There have been many advances in the care of children with SCD in the UK. The establishment of the linked antenatal and neonatal screening programmes has allowed early diagnosis, education and intervention including the introductive of penicillin prophylaxis and vaccination which has helped to reduce deaths due to pneumococcal disease. Implementation of the transcranial Doppler screening programme has significantly reduced the risk of acute ischaemic stroke in childhood.
With improvements in the management of life-threatening acute complications like acute chest syndrome, nowadays most children in the UK can expect to grow up to be adults and lead functional lives. However, with improving life expectancy and risk of cumulative organ damage, many adults have frequent symptoms including episodes of debilitating pain which impacts on their quality of life. Therefore, the focus has shifted to more early intervention and a more holistic and multidisciplinary approach to supporting individuals and their families.
At present two sickle modifying treatments are available to UK patients: hydroxycarbamide which remains the only licensed medication, and transfusion therapy which can be delivered as simple top up transfusions or by automated red cell exchange. Curative treatment with allogeneic bone marrow transplantation has good outcomes and is considered in symptomatic children who have a fully matched sibling donor. Reduced intensity conditioning transplant options in adult patients and the advent of gene therapy promises to make this more applicable to a wider group of patients.
In the interim, increased clinical pharmacological research interest in developing and investigating new drugs targeting different components of the patho-biology has inspired hope amongst patients, their families and the multidisciplinary teams treating them. Soon we may have new treatments to prevent disease progression and help with symptoms and curative options which are safe, effective and available to all.
Dr Banu Kaya graduated from the United Medical and Dental School of Guy’s and St Thomas’ Hospitals in 1998. Following completion of her specialty training in 2007 she joined Barts Health NHS as a consultant haematologist based within the departments of Paediatric Haematology/Oncology and Clinical Haematology. Dr Kaya currently jointly leads the haemoglobinopathy services at Barts Health. Her areas of interest are paediatric haematology and red cell disorders, particularly haemoglobinopathies. She co-led the National Haemoglobin Disorders Peer Review Programme (2014-2016) and was joint Chair of the programme steering group. She is the UK Chief Investigator for a number of clinical trials and is committed to exploring different modalities of treatment that may help to improve outcomes and quality of life for patients with haemoglobinopathies. Dr Kaya has been a Trustee of the British Society of Haematology since April 2018.