GS Paper III

News Excerpt:

The UK drug regulator recently approved gene therapy to cure sickle cell disease and thalassaemia.

What is Sickle cell disease?

• Red blood cells with sickle cell disease have a crescent form due to a genetic defect.
• Because sickle-shaped cells are more difficult to manoeuvre in the vessels than disc-shaped regular cells, blood flow becomes obstructed. 
• Severe pain, potentially fatal infections, anaemia, or stroke can result from this.

• Every year, between 30,000 and 40,000 babies in India are thought to be born with this disorder.
• Those who receive a pair of faulty genes from both parents have the symptoms.
• One can lead a normal life even if they only have one copy of the gene from one parent.

About Thalassaemia Disease:

Thalassemia is an inherited blood disorder.

• In the case of thalassaemia, too, people who inherit a pair of genes from both parents experience symptoms like severe anaemia.
• Low haemoglobin levels caused by thalassaemia lead to exhaustion, dyspnea, and erratic heartbeats. 
  • People with the condition need blood transfusions throughout their life. 
  • Additionally, the transfusions cause the body to accumulate too much iron, which calls for chelation.
• With roughly 1-1.5 lakh children suffering from thalassaemia major, India likewise has the highest number of such cases worldwide.

How does the therapy work?

Both sickle cell disease and thalassaemia are caused by errors in the gene for haemoglobin, a protein in the red blood cells that carry oxygen to organs and tissues.

• The treatment uses the patient's own blood stem cells, which are precisely edited using Crispr-Cas9.
• A gene called BCL11A, which is essential for converting foetal to adult haemoglobin, is being targeted through this therapy.
• The foetal haemoglobin does not carry the same abnormalities as the adult haemoglobin, which is naturally present in all newborns.
• The treatment reduces the symptoms of both disorders by encouraging the body to produce more of this foetal haemoglobin through natural processes.

How is the therapy prepared and given?

• The doctor must first collect blood stem cells from the bone marrow using apheresis to filter out the blood for different components. 
• After that, the cells are sent to the manufacturing facility, where they undergo testing and editing over the course of around six months.
• Before a transplant with the edited cells, the doctor gives a conditioning medicine for a few days to clear the bone marrow of other cells that will be replaced by the modified cells.
• Similar to autologous stem cell transplant side effects, the treatment's adverse effects include nausea, exhaustion, fever, and an elevated risk of infection.

Challenges of this treatment:

• The procedure cost is very high.
• The lack of local manufacturing facilities necessitates sending the extracted blood stem cells across the countries.
• Since many sufferers of these illnesses reside in poorer nations, it is unlikely that they will be able to pay for the therapy.

Mains PYQ

Q. Stem cell therapy is gaining popularity in India to treat a wide variety of medical conditions including leukaemia, Thalassemia, damaged cornea and several burns. Describe briefly what stem cell therapy is and what advantages it has over other treatments?      (UPSC 2017)