And so in that case, when we're dealing with the oxygenated form of hemoglobin, these two amino acids are found inside. And so since they cannot interact with the valley, they will not aggregate. And so that's why the aggregation only takes place in the deoxygenated state of hemoglobin. So this is what sickle cell anemia is. Sickle cell anemia is basically the condition in which the genes that code for the beta subunits are basically they have some type of genetic mistake. And so when those genes are read and we express the proteins, there's a single substitution.