Classification of hemoglobin

Hematology lecture number 3 مدرس المادة د.نوران جميل
Classification of hemoglobin

Normal hemoglobin is of various types depending on its function and the age of human.
Hemoglobin is the iron-containing protein compound within red blood cells that carries oxygen throughout the body. It is made up of heme, which is the iron-containing portion, and globin chains, which are proteins. The globin protein consists of chains of amino acids, the "building blocks" of proteins. There are several different types of globin chains, named alpha, beta, delta, and gamma. Normal hemoglobin types include:
• Hemoglobin A (Hb A): makes up about 95%-98% of hemoglobin found in adults; it contains two alpha (?) chains and two beta (?) protein chains.
• Hemoglobin A2 (Hb A2 ): makes up about 2%-3% of hemoglobin found in adults; it has two alpha (?) and two delta (?) protein chains.
• Hemoglobin F (Hb F, fetal hemoglobin): makes up to 1%-2% of hemoglobin found in adults; it has two alpha (?) and two gamma (?) protein chains. It is the primary hemoglobin produced by the fetus during pregnancy; its production usually falls shortly after birth and reaches adult level within 1-2 years.
• Embryonic hemoglobin produced in the blood islands in the embryonic yolk sac during (first week of pregnancy until the end of the pregnancy). The protein is commonly referred to as Hemoglobin ?. Blood islands are structures around the developing embryo which lead to many different parts of the circulatory system. Blood islands arise external to the developing embryo on the umbilical vesicle, allantois, connecting stalk and chorion

The quantity of the hemoglobin that is produced depends on the stage of human development. Fetal hemoglobin predominates whilst a baby is in the womb but it will start to make a small proportion of the adult type hemoglobin before birth. By the time a child is one year old there is a switch over in the amount of Fetal and Adult type hemoglobin produced. If a child has inherited normal hemoglobin the quantity produced at birth and throughout adulthood is indicated below: