And in this particular case, they basically have a non functional gene. So basically, the gene codes for a protein that is not fully functional. And this protein happens to be a protein that is very important in our body. This protein is hemoglobin. So normally, hemoglobin binds oxygen in the lungs and it unloads that oxygen in the tissues of our body and then it returns back into our lungs to pick up more oxygen. Now, in individuals with sickle cell anemia, what happens is the amino acid number six on the beta subunit chain.