







Sickle Cell Disease

Sickle Cell Disease is a blood disorder characterised with the production of abnormal haemoglobin due to a mutation in the HBB gene which encodes for the beta-globin chains of haemoglobin. This causes the formation of sickle-shaped red blood cells that do not carry oxygen efficiently.





The rigid shape of the sickled red blood cells can cause blockages in the blood vessels resulting in chronic pain and organ damage due to the oxygen deprivation. These individuals also have an increased risk of pulmonary hypertension which could lead to heart failure and many other complications.





The current treatments for Sickle Cell Disease are to manage the complications of the disease. This includes the usage of blood transfusions, antibiotics, and pain relief medications.





The Clinical Trial

Recently there were updates from a clinical trial using CRISPR to treat Sickle Cell Disease. The study is a joint effort by CRISPR Therapeutics and Vertex Pharmaceuticals.





A patient called Victoria Gray had her bone marrow cells extracted, these cells were then gene-edited using CRISPR to allow the production of fetal haemolgobin. The CRISPR edited bone marrow cells were then infused back into the patient. The theory behind this treatment was that the fetal haemoglobin would hopefully counteract the complications of the Sickle haemoglobin.





The Updates so Far

Victoria's blood test results have shown that she is producing fetal haemoglobin due to the CRISPR edited cells, and she has not been having regular transfusions nor had any emergency trips to the hospital.





It was reported by NPR , in an interview with the Doctors, that it was expected that fetal haemoglobin around 20-30% would be required in order to show the benefits of the treatment. It was found that the patient had an increase in fetal haemoglobin production which exceeded this value and most of the patient's red blood cells contained fetal haemoglobin, which is very good news.





Even though these results are very early and only from a single patient, they are promising and show the capabilities of CRISPR based therapies. Now It would be interesting to see the long term effects of this therapy and whether it can be sustained.









References:

1. https://clinicaltrials.gov/ct2/show/NCT03745287?term=crispr&cond=sickle&draw=2&rank=2

2. https://www.npr.org/sections/health-shots/2019/11/19/780510277/gene-edited-supercells-make-progress-in-fight-against-sickle-cell-disease?t=1576690746277