"Genetic Engineering" A New hope for sickle-cell patients

Genetic engineering could prove to be effective in curing sickle-cell disease, according to latest research.

• Though in early stages, it could prove to be the first ever genetic cure to this common genetic disorder.

Background

About Sickle-Cell Disease

• The RBCs in the blood contains a protein called hemoglobin, which carries oxygen throughout the body.
• Normally hemoglobin is smooth, round, disk-shaped and flexible, allowing the RBCs to flow smoothly through our bloodstreams.
• In case of patients with sickle-cell disease, the gene that codes for hemoglobin is genetically mutated making the hemoglobin sticky.
• The mutation of hemoglobin-beta gene occurs on chromosome 11. 
• The abnormal sticky hemoglobin forms rods that clump together distorting the shape of the RBCs.
• The distorted RBCs become curved and rigid taking the shape of a C-shaped sickle and hence the name.
• Sickle cell disease is a genetic blood disorder that results in deformation and break down of red blood cells in the blood.
• Sickle cell disease is the most common inherited blood disorder that can be acquired from either or both the parents who carry the defective gene.

Symptoms

• The sickle-shape and rigidity of the RBCs make it difficult to travel through the blood streams and hence the oxygen-carrying capacity of the blood.
• This oxygen deprivation to tissues and organs can lead to
• Severe pain called ‘crises’
• Damage to organs
• Repeated pneumonia
• Swelling of hands and feet
• Enlargement of the spleen
• Stroke
• If the RBCs are severely distorted and become rigid, it can lead to a low-blood condition called anemia, as the distorted RBCs survive only for 10-20 days compared to 120 days in normal condition.

Treatment

• Currently there is no cure to sickle-cell disease.
• Low-hemoglobin conditions are usually treated with blood-transfusions.
• The other remedy is bone marrow transplant.

Genetic Cure to SCD

• The researchers are working on a genetic engineering solution to treat SCD.
• The treatment involves removal of stem cells from the patient’s bone marrow.
• The stem cells so removed are genetically modified.
• The genetically modified cells are infused back in the bone marrow and helps form healthy RBCs.

Incidence of SCD

• Globally, around 300,000 infants are born with SCD every year.
• The disease is most common in sub-Saharan Africa.
• Other regions known for the incidence of SCD are Southern Europe, Middle East and Asia including India.
• In India, prevalence of sickle cell trait is high in central India especially Maharashtra, Chhattisgarh and Odisha.
• Odisha has a significantly high percentage of the population, about 34% in some regions, that carries the sickle gene.

Global Initiatives to fight SCD

• In 2008, the UN General Assembly, recognizing sickle cell disease as a public health concern, established June 19 as World Sickle Cell Day.
• The Global Sickle Cell Disease Network is periodically conducting the Global Congress on Sickle Cell Disease staring from 2012.
• The 3rd and the latest Global Congress on Sickle Cell Disease and Bone Marrow Transplantation was held in Bhubaneswar in February 2017.