Hemoglobinopathy is the medical term for a group of inherited blood disorders and diseases that primarily affect red blood cells. They are single-gene disorders and, in most cases, they are inherited as autosomal co-dominant traits.There are two main groups: abnormal structural hemoglobin variants caused by mutations in the hemoglobin genes, and the thalassemias, which are caused by an underproduction of otherwise normal hemoglobin molecules. The main structural hemoglobin variants are HbS, HbE and HbC. The main types of thalassemia are alpha-thalassemia and beta thalassemia.The two conditions may overlap because some conditions which cause abnormalities in hemoglobin proteins  also affect their production. Some hemoglobin variants do not cause pathology or anemia, and thus are often not classed as hemoglobinopathies. Hemoglobin structural biology
Normal human hemoglobins are tetrameric proteins composed of two pairs of globin chains, each of which contains one alpha-like (α-like) chain and one beta-like (β-like) chain. Each globin chain is associated with an iron-containing heme moiety. Throughout life, the synthesis of the alpha-like and the beta-like (also called non-alpha-like) chains is balanced so that their ratio is relatively constant and there is no excess of either type.The specific alpha and beta-like chains that are incorporated into Hb are highly regulated during development:
Embryonic Hbs are expressed as early as four to six weeks of embryogenesis and disappear around the eighth week of gestation as they are replaced by fetal Hb.
Omacetaxine mepesuccinate can cause fetal harm when administered to a pregnant woman. Women using HHT should avoid becoming pregnant and also avoid nursing while receiving HHT. Mechanism of action
Omacetaxine is a protein translation inhibitor. It inhibits protein translation by preventing the initial elongation step of protein synthesis. It interacts with the ribosomal A-site and prevents the correct positioning of amino acid side chains of incoming aminoacyl-tRNAs. Omacetaxine acts only on the initial step of protein translation and does not inhibit protein synthesis from mRNAs that have already commenced translation. == References ==