Sickle Cell Disease (SCD) is the most common severe monogenic disorder in the world. India accounts for 14.5 per cent of the global SCD newborns, roughly over 42,000 a year, second to sub-Saharan Africa. We spoke to Dr Rahul Bhargava, the principal director & chief of Bone Marrow Transplant (BMT) department at Fortis Memorial Research Institute, Gurugram, Haryana. Excerpts:
What is sickle cell disease (SCD) and how does it affect the body?
Sickle Cell Disease (SCD) is a hereditary blood disorder where the body produces an abnormal form of haemoglobin called haemoglobin S (HbS). Generally, red blood cells are circular and flexible, allowing them to move easily through blood vessels.
However, in SCD, these cells become stiff and crescent-shaped. This irregular shape can cause the cells to cluster and obstruct blood flow, leading to a range of health issues.
It is considered the most common severe monogenic disorder in the world. What makes it such an illness?
SCD is considered the most common severe monogenic disorder due to its widespread prevalence and significant impact on those affected. The disorder is caused by a single gene mutation, yet it results in substantial morbidity and mortality. The global burden is particularly high in regions where malaria is endemic, as the sickle cell trait offers some protection against malaria, leading to a higher prevalence of the disease.
What are the genetic causes of SCD, and how is it inherited?
SCD is caused by a mutation in the HBB gene on Chromosome 11, which encodes the beta-globin subunit of haemoglobin. The mutation involves a substitution of valine for glutamic acid at the sixth position of the beta-globin chain, forming HbS instead of normal haemoglobin A (HbA).
SCD is inherited in an autosomal recessive pattern:
It seems that there is an ethnic or racial vulnerability for SCD. Europe and North America is less affected but sub-Saharan Africa and India are worst affected. Why?
The higher prevalence of SCD in sub-Saharan Africa and India is largely due to the selective advantage of the sickle cell trait in malaria-endemic regions. Carriers of the sickle cell trait (HbAS) have a higher resistance to malaria, which increases their survival rates and, consequently, the frequency of the HbS allele in these populations. Over generations, this evolutionary advantage has led to a higher prevalence of SCD in these regions compared to Europe and North America, where malaria is not endemic.
India accounts for 14.5 per cent of the global SCD newborns, with over 42,000 cases annually. Why is the incidence so high in India?
India’s high incidence of SCD can be attributed to several factors:
Are there specific populations within India or sub-Saharan Africa that are more affected by SCD?
Yes, certain populations within these regions are more affected by SCD:
What are the common symptoms of SCD? At what age do symptoms typically begin to manifest in children with SCD?
Common symptoms of SCD include:
Symptoms typically begin to manifest in children around five to six months of age when foetal haemoglobin (HbF) is replaced by adult haemoglobin (HbS).
How is SCD diagnosed, especially among newborns? Are there any screening programmes in place in high-prevalence areas?
SCD can be diagnosed through:
Many high-prevalence areas have established newborn screening programmes to identify and manage SCD early. These programmes are routine in parts of Africa, India, the United States, and other regions with significant SCD prevalence.
What are the current treatment options available for individuals with SCD?
Treatment options for SCD include:
What can be done to fight SCD at the global level?
Yes, lifestyle changes and interventions can help manage SCD symptoms:
These measures can significantly improve the quality of life for individuals with SCD and reduce the global burden of the disease.
Link to article –
World Sickle Cell Day: Doctor explains how to keep newborns safe
