Sickle cell anemia

Sickle cell anemia was the first molecular disease first discovered in the world in 1949, thus creating the era of molecular biology of diseases. Its molecular pathology is that a single base mutation occurs in the gene. The sixth codon of the normal gene is GAG, which compiles glutamic acid. After mutation, it becomes GTG and compiles valine. This single amino acid substitution forms HbS. In clinical practice, there are three main forms of hemoglobin S disease: ① homozygous state, that is, sickle cell anemia; ② heterozygous state, that is, sickle cell traits; ③ double heterozygous state of hemoglobin S and other abnormal hemoglobin, including hemoglobin S-globin production is anemia, hemoglobin C disease, hemoglobin D disease, etc. In the deoxygenated state, the solubility of HbS is 1/40 of that of deoxygenated HbA. Therefore, deoxidation can cause red blood cells to deform stiffly and become sickle-shaped, hence the name.