Today marks the celebration of World Sickle Cell Day an event that is annually celebrated in order to commemorate and raise awareness about the disease and subsequently put forward the rights of those affected by the disease.
The day also brings into the purview of promoting early diagnosis, access to treatment, and an enhancement of the quality of life for those affected by it. Sickle Cell Disease (SCD) is the most prevalent severe monogenic disorder globally. India represents 14.5% of all newborns with SCD worldwide, totalling more than 42,000 each year, second only to sub-Saharan Africa.
Dr Rahul Bhargava, the principal director & chief of the Bone Marrow Transplant (BMT) department at Fortis Memorial Research Institute, Gurugram, Haryana, illuminated us with his thoughts on the disease.
The Disease is a blood disorder which is passed down hereditarily and results in the production of abnormal haemoglobin known as haemoglobin S (HbS). The red blood cells generally have a shape that is circular and flexible, which allows them to manoeuvre easily through blood vessels.
However, what happens in SCD is that the shape of these red blood cells becomes crescent-shaped and stiff. This irregular shape causes the cells to cluster and obstruct the flow of blood, which in turn causes a lot of health-related issues.
Pain crises (vaso-occlusive crises): Obstructed blood flow can trigger severe pain episodes in the chest, abdomen, and joints.
Chronic hemolytic anaemia: Fragile sickle cells break down easily and die, leading to a continual shortage of red blood cells.
Infections: SCD weakens the spleen, increasing susceptibility to infections.
Organ damage: Persistent blockages and anaemia can lead to damage in organs such as the spleen, liver, kidneys, lungs, and brain.
Stroke: Reduced blood flow to the brain can result in a stroke.
Sickle Cell Disease (SCD) is recognized as the most prevalent severe genetic disorder due to its wide distribution and profound effects on those it affects. Despite being caused by a single gene mutation, it imposes considerable health challenges and mortality rates. Its impact is particularly pronounced in regions where malaria is common, as the sickle cell trait provides some resistance to malaria, thereby contributing to higher rates of SCD prevalence.
The mutation of the HBB gene on chromosome 11 causes the SCD which encodes the beta-globin subunit of hemoglobin. The mutation results in a substitution of valine for glutamic acid at the sixth position of the beta-globin chain, resulting in the formation of HbS instead of normal haemoglobin A (HbA).
Sickle Cell Disease (SCD) is inherited in an autosomal recessive pattern:
Homozygous (HbSS): Individuals who inherit two copies of the HbS gene experience symptoms of SCD.
Heterozygous (HbAS): Individuals with one HbS gene and one normal HbA gene are carriers, known as having the sickle cell trait. They typically do not show symptoms but can pass the gene to their offspring.
Sickle Cell Disease (SCD) is prevalent globally, particularly in regions like India and sub-Saharan Africa, where its incidence is influenced by the protective effect of the sickle cell trait against malaria. This genetic disorder, caused by a mutation substituting valine for glutamic acid at the sixth position of the beta-globin chain, results in the formation of haemoglobin S (HbS) instead of the normal haemoglobin A (HbA).
Regional Prevalence and Factors Contributing to High Incidence
India, accounting for 14.5% of global SCD cases with over 42,000 newborns affected annually, shows a high incidence due to diverse genetic backgrounds and historical malaria prevalence in central and eastern regions. Endogamous practices and India’s large population further contribute to the spread of the HbS allele.
Most Affected Populations in India and Sub-Saharan Africa
In India, tribal groups like the Gond, Baiga, Bhil, and Adivasi communities in Maharashtra, Madhya Pradesh, Odisha, and Chhattisgarh are disproportionately affected. Similarly, countries such as Nigeria, the Democratic Republic of Congo, and Ghana in sub-Saharan Africa have significant SCD prevalence.
Symptoms and Onset
Common symptoms of SCD, which typically manifest around five to six months of age, include pain crises, chronic anaemia, swelling, infections, delayed growth, puberty, and vision problems due to organ damage and reduced blood flow to the brain.
Diagnosis and Screening Programs
Diagnosis of SCD involves newborn screening using techniques like haemoglobin electrophoresis or genetic testing. Many high-prevalence regions have established screening programs to identify and manage SCD early, ensuring timely interventions.
Current Treatment Options
Treatment for SCD includes pain management, hydroxyurea to increase fetal haemoglobin production, blood transfusions, bone marrow or stem cell transplantation, and emerging gene therapy aimed at correcting the genetic mutation causing the disease.
Global Strategies to Combat SCD
Globally, efforts focus on expanding newborn screening, increasing awareness, improving healthcare access, supporting research for new therapies, and providing genetic counselling to at-risk couples. Lifestyle adjustments such as hydration, avoiding extreme temperatures, regular exercise, and a healthy diet also play crucial roles in managing SCD symptoms and improving quality of life.
By implementing these measures, the global community aims to alleviate the burden of SCD, enhance treatment outcomes, and ultimately work towards finding a cure for this challenging genetic disorder.
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