Sickle cell disease (SCD) is the most common inherited blood disorder in the US and affects million people worldwide. The mutation of just one amino acid in the beta-chain of hemoglobin (Hb) causes the production of an altered Hemoglobin S.
This results in multiple health problems like severe pain due to tissue damage, hypertension, kidney failure, anemia and stroke.
It was 1948 when pediatrics Janet Watson postulated for the first time the importance of fetal hemoglobin (HbF;α2γ2), in sickle cell diseases. Meanwhile, it has been shown that the re-activation of fetal hemoglobin (HbF) expression prevents the polymerization of sickle hemoglobin and therefore might prevent or retard the resulting health issues.
BCL11A erythroid enhancer, is responsible for the repression of fetal hemoglobin and for the activation of beta-hemoglobin. Introduction of point mutations in the core sequences of the BCL11A erythroid enhancer region causes de-repression of HbF in adult cells and reduced expression of the sickle-cell beta-hemoglobin and formation of polymerized sickle-hemoglobin.
Using this approach allows to use CRISPR / Cas9 based NHEJ repair to introduce point mutations into the BCL11A enhancer, without the necessity of co-transfection of a DNA template as it would be required for a repair of the effected beta-globin gene
- in vitro differentiated erythrocytes from SCD did resist sickling
- in vitro differentiated erythrocytes from beta-thalassemia patients showed higher frequency of enucleation, large size and circular shape erythroid cells due to improved globin chain balance.
