Normal Adult Haemoglobin A

The blood is made up of different parts and each part has a different function. There are red blood cells – they carry oxygen around the body, white blood cells – help the body to fight infection, platelets – clots the blood and stops bleeding and plasma – which is mainly water.

The normal red blood cell is round, soft, spongy and pliable and resembles the shape of a doughnut that has been pressed in the middle slightly. Red blood cells are made in the bone marrow and live for 120 days approximately before they get destroyed and disposed of by the body but the body is constantly making new red blood cells.

The red blood cells contain a substance called haemoglobin, they are like tiny bubbles which combine with the air (oxygen) in the lungs, carry round the body to all the body parts to keep the body tissues and organs alive. Haemoglobin gives blood its red colour when it contains oxygen. These haemoglobin molecules (bubbles) stay freely flowing in the red blood cell, as illustrated in the picture below. There are different types of normal haemoglobin flowing in red blood cell, Adult Haemoglobin, Fetal Haemoglobin and minor adult Haemoglobin A2 (A2).

The type of haemoglobin gene which a person has inherited from their parents determines the type of Adult haemoglobin they will have. Genes always come in pairs one from the mother and one from the father. Therefore, every individual inherits two Adult haemoglobin genes.

Adult haemoglobin is made up of two beta and two pairs of alpha chains, see Haemoglobin.

The normal and most common Adult haemoglobin worldwide is haemoglobin A. If a person inherits two of these from their parents they will have Haemoglobin AA, commonly written Hb AA. This means they have inherited normal beta and alpha genes and are able to produce the correct quantity and quality of beta and alpha chains to make Haemoglobin A, see Inheritance of Haemoglobin.

There are two other normal haemoglobins in the red blood cell this is Fetal (F) Haemoglobin which predominates when a baby is in the womb and Haemoglobin A2 which is an adult type haemoglobin, but inefficient at carrying much oxygen.

The Family Connection

People can inherit unusual haemoglobin combinations either as a healthy carrier (trait) or a disease state, for examples see Haemoglobin.

Once an unusual haemoglobin gene has been found in one family member it is important to be aware that other members of the same family may also have the unusual haemoglobin gene. Therefore, it is important to share the information especially with those who are planning to get married, start a family or have more children - brother, sisters, aunts, uncles, cousins.

Testing for Haemoglobin

Anyone who wants to be tested to find out which haemoglobin they have inherited from their parents can visit their GP or contact their local specialist National Sickle Cell / Thalassaemia Centre.