So the sickle cells slow down the blood flow in our veins and they can clog the veins of our body, leading to tissue damage which can be very, very painful. Painful. Now, let's move on to the third type of Autosole recessive disease found in humans known as cystic fibrosis. So sickle cell anemia, by the way, is very prevalent in African American population. I believe one in one, two African Americans living in the US. Are heterozygous for this particular disease.